The Science and Practice of Photographic Printing by Cezar Popescu

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路THE SCIENCE AND PRACTICE OF

路PHOTOGRAPHIC PRINTING BY

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LLOYD I. ~NODGRASS,. B. S. DEPARTMENT OF PRINTING AND FINISHING ILLINOIS CoLLEGE OF PHOTOGRAPHY. MEIIBBR ov TECHNICAL PHoTOGRAPHIC AND MICROSCOPICAL SOCIETY. MSKBBll. 011' PHOTOGRAPBBRs" AssociATION 011' AKBRICA.

WITH 58 ILLUSTRATIONS

EFFINGHAM, ILLINOIS

1923

1P23, BY 1. SNODGRASS. (All Riiltto Ruen~ed.) CoPYRIGHT,

LLOYD

Worma11 Printe171 Incorporated,

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PREFACE The necessity for adequate information on Photographic Printing and Finishing in concise form, was brought forcibly to the writer's attention during his earlier years of the study of photography. Because of the lack of suitable text and reference books, he has later found it necessary to bring together from various sources considerable material for a course of lectures and experiments for instruction work. The present volume is a development of these lectures and is written as a practical text book for the serious worker, whether he be an advanced amateur or a professional photographer. It is not thought, however, that this treatment will make it of less general interest to the casual reader or of less value to the student who is interested in photogTaphy purely as a science. While there are many photographic treatises and monographs on the market, few deal with printing and finishing, and as a rule, they are too complex and detailed for the average photographic worker. So he naturally turns to the popular handbooks, which at the other extreme, merely give directions as to procedure without explaining the principles involved. The author has attempted in this book to take a middle ground and give an accurate compilation of the printing data in common use, together with the scientific basis of the work. In dealing with the subject, he has had in mind the needs of the professional worker who has not the time for abstract scientific study but who has passed beyond the elementary stage of taking things for granted. He has also considered the amateur who is interested in photography as a craft

PREFACE

and science rather than a mere mechanical method of expression and who perhaps is desirous of entering the ranks of professional photography. Since the writer has for some years been teaching photography in an institution which prepares students for entrance into professional work,' due emphasis has been placed on the practica1 side. However, this has not been allowed to obscure the fact that the worker must build his knowledge on a thoro understanding of the underlying principles, if he is to work intelligently and be able to locate and correct his mistakes. Only those methods in more general use have been taken up at length, since in a book of this kind, it is obviously impossible to touch upon al'l the printing processes or include all formulae. ri'hose included are recommended by leading photographic authorities, the majority having been used by the author under actual working conditions. The series of experiments included in the Appendix was originally used in printing classes with college students. Reference is made to them from time to time in the text and it is suggested that the worker who is really interested in acquiring a scientific understanding of the work, try these experiments for himself in his own workroom. If carried out in conjunction with a study of the text, the resulting experimenta'l evidence will be all the more informative. No special originality is claimed in the material given in this work, but it is hoped that this method of presentation will prove of interest and profit. The standard photographic books and magazines have been freely drawn upon, both for fact and theory, supplemented by the author's own investigations. A bibliography is included in the Appendix and the reader is urged to consult the books listed for further information on specific subjects.

l>REFAC:m

The author is especially indebted to Alfred B. Hitchins, Ph. D., Director of The Ansco Company's Research Laboratory, who has made several valuable suggestions after carefully reading and criticising the manuscript, giving special attention to those portions dealing with the chemistry of printing. Grateful acknowledgement is due my wife, Lillian Teller Snodgrass, whp by helpful suggestion concerning the subject matter and in its revision and grammatical arrangement. has made possible this volume. Effingham, Illinois. Januo:ry, 191/J.

LLOYD

SNODGRASS.

CONTENTS CHAPTER

PAGE

PREFACE---------------------------------·-·······················-··········-·····

1. INTRODUCTION .........................................................

IMPORTANCE OF PRINTING--NEED OF KNOWLEDGE-SOURCES OF INFORMATION-FIELD OF EXPElllMENTATION.

II. WORKROOMS ------------------------·· -----------------------------------

PRINTING ROOM:

LoCATION-SANITATION -PLANS - ARRANGEMENT ENTRANCEVENTILATION -WINDOWs--FLOORs--WALLS AND CEILING--SINK8--HEATING FACILITIES; FINISHING ROOM: PLANS- ARRANGEMENT.

III. EQUIPMENT AND SUPPLIES-------------------- 30 PRINTING EQUIPMENT BOTTLES- GRADUATEs--PRINTING MACHINE- SAFELIGHTSSCALES TRAYS PRINTING SUPPLIESCHEMICAL SUPPLIE8--FINISHING EQUIPMENT -FINISHING SUPPLIES.

IV. ELEMENTARY CHEMISTRY .......................

PURPOSE OF CHAPTER-PHYSICAL AND CHEMICAL CHANGEs--ELEMENTs--ATOMs--ATOMIC WEIGHT-MOLECULAR WEIGHT-FORMULA -PROPERTIES OF MATTER-REACTION8--SOI,UTIONS- DELIQUESCENCE AND EFFLORESCENCE- ACIDs--BASES NEUTRALIZATION -SALTs--OXIDATION AND REDUCTION.

V. PREPARATION OF SOLUTIONS ............

SYSTEMS OF WEIGHTS AND MEASUREs--PURITY 0.' CHEl\IICAL8--SOLUTION OF CHEMICALS -METHODS OF MIXING SOLUTIONS-FILTRATION OF SOLUTIONs--STOCK SOLUTIONS.

VI. PRINTING PAPERS .......................... ..................... 62 COMPOSITION- CHLORIDE PAPERs--BROMIDE P APER8--PRINTING-0UT-PAPERS.

CONTENTS PAGE

CHAPTER

VII. CHOICE OF PRINTING PAPERS ____________

PAPER STOCK AND SURFACE-COLOR-TONAL VALUEs--SCALE OF CONTRAST IN LIGHTING -SCALE OF CONTRAST IN THE NEGATIVESCALE OF CONTRAST IN PAPER-CHOICE OF CONTRAST-LoNG SCALE NEGATIVE--SHORT SCALE NEGATIVE GENERAL CONSIDERATIONS.

VIII. PREPARATION AND EXPOSURE _________ 79 IMPROVEMENT OF DEFECTIVE NEGATIVES PRINTING MACHINES CORRECT EXPOSURE -DETEHMINATION OF LENGTH OF EXPOSURE -DODGING-DIFFUSION PRINTING-USE OF TINTED BORDERs--TINTING MASKs--CHEMISTRY OF LIGHT ACTION LATENT IMAGE THEORIES.

IX. VIGNETTING-----------------------------------------------------------------

SUITABILITY-IDEAL NEGATIVE FOR VIGNETTING PREPARATION OF NEGATIVE MECHANICAL DEVICEs--PRINTING FRAME METHOD POST-OFFICE PAPER METHOD - SAND METHOD- AIR BRUSH METHOD CYANIDEIODIDE METHOD-COMBINATION VIGNETTES.

X. COMBINATION PRINTING--------------------------- 105 COPYING METHOD-MASKING METHOD.

XI. DEVELOPMENT __________________ .. ---------------------------------- 111 FUNCTION OF DEVELOPERS CHEMISTRY OF DEVELOPMENT-DEVELOPING REAGENTS OTHER CHEMICALs--CLEANING SOLUTIONMETOL-HYDROCHINON DEVELOPER STOCK SOLUTIONs--MODIFICATION OF DEVELOPERDEVELOPING THE PRINT -- DEFECTS IN DEVELOPMENT-AMIDOL DEVELOPER.

XII. FIXATION ------------------------------------------------------------------------ 132 HYPo--SoDIUM SULPHITE ACETIC ACID ALUM-ADVANTAGES OF SHORT STOP BATHFORMULA- CHEMICAL ACTION - CHEMISTRY OF FIXATION-ACID FIXING BATH-USE OF FIXING BATH.

CONTENTS

11 PAGE

CHAPTER

XIII. WASHING AND DRYING -------------------------------- 142 NECESSITY OF WASHING-TEMPERATURE OF WATER- METHODS - TIME OF WASHINGTESTS ~'OR HYPo--HYPO ELIMINATORs-NoNREl\'IOVAL OFHYPo--RATE OFDRYING-METHODs-USE m· FLATTENING CARDs-FLATTENING SOLUTIONS.

XIV. TONING --------------------------------------------------------------------------------- 151 CHOICE OF COWR-GRADATION-PERMANENCY CHOICE OF NEGATIVES AND PAPERHYPO ALUM METHOD--MODIFICATIONs-REDEVELOPl\IENT METHOD-LIVER OF SULPHUR METHOD -- RE-BLEACHING OF SEPIA PRINTS - FACTORS AFFECTING WARMTH OF SEPIA TONEs-CHALK RED TONES BLUE TONES -GREEN TONES--COMBINATION TONING.

XV. DEFECTS IN PRINTS ------------------------------------------ 170 ABRASION MARKs- BLISTERs-UNSATISFACTORY CoWR- EXCESSIVE CONTRAST-DARK PRINTs-DEPOSITs-FADING FLATNESSFOG-MOTTLED APPEARANCE MUDDY APPEARANCE-SPOTS STAINs-UNEVEN DEVELOPMENT-WEAK PRINTS.

XVI. FINISHING ---······-··--············-···-----········ ---·---·····--·------------ 184 SELECTION OF MOUNT8--TRIMMING-PLATESINKING-EMBOSSING- MOUNTING--CLEANING SPOTTING AIR BRUSH WORK SKETCHING- COWRING FRAMING- MISCELLANEOUS.

XVII. PROJECTION PRINTING ADVANTAGES DISADVANTAGES EQUIPMENT-ENLARGING PAPERs-FOCUSING-SECURING DIFFUSION-EXPOSURE-DODGINGVIGNETTING DEVELOPMENT FIXING, WASHING, AND DRYING-TONING- FINISHING--LIFE SIZE ENLARGEMENTS.

204

CONTENTS

CHAPTER

PAGE

XVIII. COMMERCIAL PRINTING .............................. 223 STANDARDS- BLOCKING ETCHING-COMMERCIAL PRINTING PAPERs--PRINTING MACHINE EXPOSURE DEVELOPERS DEVELOPMENT FIXING AND WASHING-DRYING FERROTYPING FINISHING LINE DRAWINGS CYANIDE-IODIDE REDUCER COLORING-BLUE PRINTS.

XIX. PRINTING ON GLASS .......................................... 243 LANTERN SLIDEs--SIZE-USE-METHODSEXPOSURE- DEVELOPMENT- FIXATIONSLIDES IN COLORs--TITLES MOUNTINGTRANSPARENCIEs--0PALs--DORETYPES.

XX. PRINTING-OUT PROCESSES ........................ 252 SILVER PRINTING-OUT-PAPERS PLATINUM PRINTING CARBON PRINTING CARBRO PRINTING PROCESS GUM PRINTING OIL PRINTING.

XXI. PRINTING IN COLORS ....................................... 265 COLOR COLOR PHOTOGRAPHY SCREENPLATE PROCESSEs--COLOR SEPARATION NEGATIVES- COLOR PRINTING- THREE-COLOR CARBON PRINTING RAYDEX THREE-COLOR PROCESs--THREE-COLOR GUM PRINTINGPINATYPE PROCESs--RELIEF PROCESs--MORDANTING PROCESSEs--THREE-COLOR PHOTOENGRAVING-CONCLUSION.

APPENDIX A. LABORATORY MANUAL ................................. 276 EXPERIMENTS: (1) CHEMICAL REACTIONS. (2) OXIDATION. (3) PURIFICATION OF WATER. (4) PREPARATION OF METOLHYDROCHINON DEVELOPER. (5) ACID HYPO FIXING BATH. (6) PREPARATION OF HYPO ALUM SEPIA BATH. (7) TESTING SAFELIGHTS. (8) COMPARISON OF SHORT AND LoNG SCALE PAPERS. ( 9) VARIATION OF POTASSIUM BROMIDE IN THE DEVELOPER. (:\.0)

CONTENTS

13 PAGE

VARIATION IN TEMPERATURE OF DEVELOPER. ( 11) USE OF' SOFT AND CONTRAST DEVEWPERS. (12) EFFECT OF POTASSIUM IODIDE IN DEVEWPER. ( 13) EFFECT OF OMISSION OF CERTAIN CHEMICALS. (14) EXHAUSTION OF FIXING BATH. (15) VARIATION IN SEPIA TONES THRU EXPOSURE AND DEVEWPMENT. (16) COMPARISON OF TONING METHODS. (17) TESTS FOR HYPO. (18) COMPARISON OF WASHING METHODS. (19) RELATION OF ExPOSURE TU SIZE IN ENLARGING. (20) DIFFUSION METHODS. (21) VARIATION IN EXPOSURE AND DEVEWPMENT OF BROMIDE p APERS. (22) EFFECT OF HYPO IN DEVEWPER. (23) EFFECT OF DAMPNESS ON PAPER. (24) EFFECT OF SULPHIDE FUMES ON PAPER. (25) PREPARATION OF BLUE PRINT PAPER.

B. TABLE OF ATOMIC WEIGHTS .................. 289 C. TABLE OF SOLUBILITIES .............................. 290 D. TABLE FOR REDUCING AND ENLARGING ···············································-··········· 292 E. BIBLIOGRAPHY ······································-················· 293 INDEX·······················-··············································-···················-················· 297

ILLUSTRATIONS

LIST OF ILLUSTRATIONS.

Figure Page !-Floor Plan of Printing Room ............................................ 22 2-A Corner of the Printing Room ........................................ 23 3-Window Ventilator .................................................................. 26 4-Floor Plan of Finishing Room ............................................ 28 5-Home-Made Printing Machines ............................................ 32 6--Wiring Diagram ........................................................................ 33 7-Flattening Press ...................................................................... 38 8---Distillation of Water ............................................................ 55 9-Comparative Paper Contrasts (Shown by Test Screen Negative) .............................................................................. 72 10-Long Scale Negative .............................................................. 74 11-Long Scale Negative on Long Scale Paper .................... 74 12-Long Scale Negative on Short Scale Paper .................... 74 13-Short Scale Negative ............................................................ 71'1 14-Short .Scale Negative on Short Scale Paper .................... 75 15-Short Scale Negative on Long Scale Paper .................... 76 16--Professional Printing Machine ............................................ 81 17-Professional Printing Machine .............................................. 82 18---Exposure Test Rack ................................................................ 85 19-Showing Tinted Border ............................................................ 88 20--Tinting Mask............................................................................ 89 21-Vignetting: Printing Frame Method................................ 96 22--Correct Form of Vignette .................................................... 97 23-lncorrect Form of Vignette ................................................ 98 24-Vignetting: Sand Method .................................................... 100 25-Combination Vignette .................. .......................................... 103 26--Combination Printing : Prints from Defective Negatives ........................................................................................ 107 27-Combination Printing : Masks ............................................ 108 28-Combination Print'ng : Prints fro.m Masked Negatives 109 29-Combination Printing : Finished Picture ........................ 110 30-Strips Developed in Soft 1and Contra.o;t Developers ........ 120 31-Print Developed in Soft Developer .................................... 121 32-Print Developed in Contrast Developer ............................ 121 33-Two Solution Storage Device ............................................ 122 34-Print Underexposed with Forced Development ............ 128 35-Print with Correct Exposure and Development .............. 128 36--Print Overexposed with Underdevelopment .................... 128 37-Commercial Washer ................................................................ 144 38-Commercial Dryer .................................................................... 148 39--Types flf Fold~re ........................................... " ....................... 187

ILLUSTRATIONS

4()..-Finishing Tools .......................................................................... 41-Easter Egg (air brushed) .................................................... 42-Eastman Projection Printer ................................................ 43-Rexo Automatic Enlarger .................................................... 44-Lares-Master Projection Printer ........................................ 4~ontact Print .............................................................................. 46-Diffusion thru Glass ................................................................ 47-Diffusion by Projection, Using Soft Focus Lens ............ 48--Blocking Materials .................................................................. 49--Etl:hed Piece .............................................................................. 5()..-Amateur Printer .................................................................... 51-Inked-in Print ............................................................................ 52-Line Drawing ....................â&#x20AC;˘...................................................... 63-Doretype ....................................................................................

190 196 207 208 209 214 214 214 225 227 229 239 239 251

CHAPTER I. INTRODUCTION.

Impot1ance of Printing.-Printing is perhaps the most interesting of all the phases of photographic work. While correct lighting, exposure, and negativemaking cannot be too strongly emphasized, it is after all the finished print that has been the end in view thru each successive step. If success in this field is to be consistent and not accidental, the printer must have a thoro knowledge of the chemical basis of the work, and know how to reproduce the tonal values of the negative and to give the precise gradation in monochrome which he desires. Need of Knowledge.-The old time photographer was necessarily somewhat of a chemist for he was obliged to prepare his own plates and sensitize his own paper. Evidence of this technical skill is seen in his finished work. But today, the very perfection of photographic products is often one of the causes of failure of many a wou1d-be photographer. Interested in the work from the artistic end and realizing that developers may be purchased ready for use, he all too often enters the photographic ranks with practically no knowledge of the actions of the various chemicals or the underlying reasons for the different steps of the work. By the judicious use of common sense he is able to produce fairly good technical results-sometimes. But he soon learns that the mere following of prescribed fonnulae wil'l not always give the results desired. New and varied factors such as variations in the chemicals, impurities in the water, and changes in

PHOTOGRAPHIC PRINTING

temperature will often cause failure for which he is unable to account. And perhaps fully as important, he is missing half the pleasure of the work thru working blindly. Just as the nature-lover who is trained in observation will appreciate the beauties of flower, bird, and insect that the average person never even sees, so to the photographer, trained in the niceties of his science, there is a fascination, lost to the purely ''practical" worker, in observing the evolution of the dry plate or film into the finished picture. Sources of Information.-There are several ways in which this sorely needed information may be acquired. One may of course serve an apprenticeship with an experienced photographer, but this is often a slow method of attaining real proficiency. Too often mere method is shown without an adequate presentation of the reasons for the different manipulations. In fact the photographer is often in ignorance of them himself. When possible, a course in a reliable photographic school will probably give the most satisfactory resu1ts. But the average worker has to be content to gain the knowledge piecemeal as the exigencies of the daily work demand it. And necessarily under such a system, there is a constant waste of time, energy, and material. A careful perusal of this book will aid the ambitious photographer both in improving his technique and in gaining a working understanding of the rea. sons for each process. With this increased knowledge he will find that he is usually able to surmount obstacles. He will perceive what is wrong and be abte to modify or adapt formulae and methods to suit conditions. In working with new papers or in striving for certain definite effects, he can intelligently work toward a given goal. With an understanding of the basic principles underlying all papers and their mani路

INTRODUCTION

pulation, he will not be limited to any one make of paper, but with a minimum of practise should be assured of success in handling all. He will observe cause and effect in the various processes and be able to cope with the usual difficulties arising from time to time in his work. Experimentation.-Moreover, if he becomes intnested in experimentation, new and wider fields of endeavor will keep up an interest that might lag if only the commercial idea of turning out so much work a day is his ideal in life. Scientific photography is such a broad field that investigation has as yet only touched the surface. Research work is being left too much to a few inquiring workers and scientists. In past days our photographic clubs were promoters of experimentation and investigation. Now the discussions at conventions deal almost entirely with lighting and the artistic side of photography. In performing the experiments listed in the Appendix or others that suggest themselves as difficulties arise, if the worker will give close attention to all details as the reactions progress, and form the habit of jotting down in a notebook his observations and conclusions, he will have made a start in this most interesting phase of scientific photography. Sometimes the practical worker with an inquiring mind may stumble on some nugget of value that the more trained scientist without the background of a practical working knowledge may overlook. AU this opens up such a rich harvest of possibilities of real value to the thinking photographer that he can well afford to labor in this direction.

CHAPTER H. WORKROOM PLANS. Necessary Considerations.-As much time will be spent in the printing and finishing rooms, it is imperative that they be arranged for the greatest convenience and efficiency. They are two of the most important rooms in the whole studio as from them comeS! the finished product. They should be thoroly and properly equipped with the best apparatus possible, well-ventilated, and conveniently arranged. If a good grade of work is to be consistently turned out, the photographer must depart from the old idea tliat any out:of-the-way corner is good enough for the printing department. THE PRINTING ROOM.

Location.-In recent years high grade developinsr papers have largely displaced carbon, platinum, and other printing-out papers in the work turned out by a large majority of studios. This change has made it possible to use the regular developing room (dark room) for printing and enlarging. Where this is done, the ideal room for such purposes would be a half-basement, dry and capable of being well ventilated. This location gives a more even temperature both in summer and winter than a room on an upper floor. If at all damp, however, paper shou1d not be stored there but only taken down as needed, since any excessive moisture soon causes deterioration. lt must be remembered that plates and films are more sensitive than papers and that lights safe for printing would cause fog when developing plates. So

WORKROOM PLANS

if both processes are to be carried on in the one room at the same time, a curtain or other temporary partition must be used to shut . out the excessive light from the negative developing trays. Since it is more satisfactory, however, to have a separate printing room, the suggestions given here will have special application to that arrangement but may be adapted if desired to the modeling and equipping of a combination room. A room used only for printing and enlarging should be 'located on the ground floor. This will be drier than a basement, and have more even temperature than an upper floor. Sanitation.-Heating, lighting, ventilation, and all other factors affecting health and comfort should receive due consideration. A workroom that is uncomfortable will result in reduced vitality of the worker and a consequent lowering in the quantity and quality of the output. The photographer may well consider the efforts of the 'large manufacturers in their endeavor to provide ideal working conditions for their employees. There are several unsanitary conditions found in many darkrooms which should be guarded against. (a) Foulness of air, due to lack of proper ventilation, and resulting in "darkroom headache". The same air being used over and over soon becomes loaded with impurities and should be removed by the use of an exhaust electric fan. Occasionally throw the windows wide open. Good ventilation also seems to make a person less susceptible to metol and other forms of poisoning. (b) Stagnation of air. When there is no appreciable movement of the air, there will be decreased evaporation from the body of the worker, resulting in lassitude and a slight exhaustion. Even a small electric fan in the room will keep the air in circulation. (c) Excessive warmth. (d) Excessive

PHOTOGRAPIDC PRINTING

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PHOTOGRAPHIC PRINTING

moistu're. These two factors taken together result in a high humidity making the heat seem more oppressive. (e) /t'autty lighting, resulting in eyestrain and headache. This can be overcome by adequate illumination. Lamps should be so shielded that the direct rays do not reach the eyes. (f) Dampness. Since this may also affect health, the floors must be such that water and chemicals spilled may be readily removed. For convenience in cleaning, there may be an opening in the floor, covered with a grating leadirig to the basement thru a chute. Then all dirt, refuse, and papers may be swept in here and later disposed of with a minimum of trouble.

Plans.-The plans given here (Figures 1 and 2) have been worked out with the idea of providing a printing room that is compact and convenient, and at the same time a comfortable and healthful place in which to work. Naturally, no two people wiU find tll,e same ideas entirely adapted to their individual needs, but it is hoped that the plans and arrangements outlined :m,ay prove helpful. Beginners should not be deterred from starting out by the seeming complexity of the plans given, as any modification toward simplicity may easily be made. Arrangement.-Many printing rooms are so arranged that the printer wastes a large part of his time in useless steps. The room should be so laid out that each successive process of printing wil'l follow in di..: rcction as well as in order. At one corner there may be shelves or a cabinet for keeping papers for immediate use. (The stock of paper should be kept in a drier location.) Next, at the right, is the printing machine with shelves for negatives just above it. But a step away is a small cupboard for tinting masks, vignetting materials, etc. Next to the printing machine come in order the developing tray, short stop bath, fixing bath,

WORKROOM PLANS

and washing trays or tanks. If convenient the opening into the finishing room may be located at this point. Across the end of the room is a small sink which will be found most useful for mixing solutions, redeveloping, sepia-toning, reducing and intensifying. A heating device of some sort should be located here for warming the sepia bath. Caution: As sulphide fumes are very injurious to sensitive emulsions, often causing irridescent marks, streaks, and fog, these processes must not be carried on in this room while papers remain here. However, if a hood or cabinet is built down over the sink and connects to the chimney, it will carry off all gases and make the room perfectly safe for papers. On the adjoining side of the room is placed a chemical cabinet and shelves where chemicals for immediate use are kept. Right by this is a roomy work . table on one end of which the scales. may be used for weighing chemicals in case no separate room is available for that purpose. The other end may be used for the miscellaneous jobs of the printing room provided that care is taken to keep it free from chemical dust. In the remaining corner of the room is the enlarging camera and the storage cupboard for the enlarging paper in use. The trimming board is placed between the enlarging and printing machines so as to be convenient to both. Entranee.-A double or triple tum entrance with no door will be found more satisfactory than an ordinary door, curtains, or even a revolving door. (See Figure 1.) The opening should be wide enough to admit any necessary apparatus unless there is another door elsewhere. With this method of entrance there is less danger of fog than where there is the constant opening and shutting of doors, while the ventilation is materially better.

PHOTOGRAPHIC PRINTING

Ventilation.-Not only is good ventilation necessary for comfort and health but sensitive emulsions are easily affected by atmospheric conditions. Numerous troubles of which it is difficult to locate the cause are very often attributable to poor ventilation. An exhaust fan near the ceiling at the opposite end from the light-locked entrance should provide ample circulation of air and ke.ep the room cool in summer by removing the hot air which rises to the ceiling. In many studios it may be easier to equip the windows with ventilators, such as shown in Figure 3. One. or more of these together with the circulation of air thru the entrance should keep the air in good condition. When Figure 3. Window the upper sash is lowered an ample opening Ventilator is provided without danger of the white light obtaining entrance. Window Glass.-Light ruby or orange glass is perhaps best for windows, tho the ordinary glass may simply be painted a deep red. This will allow for considerable general illumination without danger of fogging sensitive paper. It would, however, be unsafe for plates and films. As an additional precaution, windows may be provided with shades to be pu1led down when the direct sun strikes them. Floot路s.-Wood floors, if kept well oiled, will prevent dust and hypo from flying around, are easily cleaned, and will be found most comfortable. Tile, cement, or other cold materials are not advisable even if covered with loose grids, as there is a tendency to allow chemicals and dust to accumulate. Walls and ceiling should be painted white, cream, or light buff. Rooms were formerly painted black or

WORKROOM PLANS

very dark shades under the mistaken notion that more reflected light would be unsafe. If no white or actinic light is allowed in the room, an abundance of reflected light will be more comfortable and make for better work. Sink.-There should be ample sink room provided for all trays and other dishes. The sinks may be made of Louisiana cypress or California redwood, and be coated with a thick coat of hard tar (roofing pitch). Or they may receive several coats of acid and alkali proof paint. While rather expensive, alberene stone is an ideal material for sinks and the tops of work benches. 3' 6" will probably be the most convenient height for the sink for the average person. Both hot and cold water faucets should be placed at convenient points as illustrated. These should be high enough above the sink that large bottles may be conveniently filled. Heating Facilities.-Provision must be made to keep the room comfortable and maintain a fairly uniform temperature or the work will suffer. A cold room not only makes difficult the keeping of the various solutions at the proper temperature, but the printer is apt to slight the work especially when washing prints by hand. THE FINISHING ROOM.

Plans.-The room used for finishing should be well lighted and heated, and for convenience should be next the printing room. Since most photographers do a certain amount of both portrait and commercial work, the plans outlined (Figure 4) are arranged with this in view.

WORKROOM PLANS

Arrangement.-Here as in the printing room an effort has been made to have each operation follow in logical order. Near the door are located cheesecloth racks, blotters, drying machine, or whatever apparatus is used for drying. Then on a long table with shelves for folders near at hand, comes the place for trimming, embossing, mounting, etc. At the end of the room, the spotting table and the desk for blocking and other work on the negative, are so arranged that both get good light from the window. By another window are the air brush tank and easel, and the table for coloring. This location is chosen for the air brush since it is so often used both for work on the negative and for water coloring. When commercial prints are being handled, the work is arranged to travel around the room in the opposite direction, starting at the right of the printing room door. The wringer and print ro1lers, rack for drying ferrotype plates, and a table for mounting and spotting are placed in order. The coloring and air brush materials are then right at hand, if they are needed. In the center of the room is a large table where printing and finishing records may be kept, amateur work sorted out, and pictures wrapped.

CHAPTER III. EQUIPMENT AND SUPPLIES. The average photographer when ready to start in business for himself is usually at a loss to know what workroom equipment and supplies are advisable. Since many established studios have accumulated so many articles of no practical va1ue, it is not wise to take them as standards. Therefore lists are given here of those items which will be of real use. Those in the first column are almost indispensable-the others should be included as far as possible. Articles which are more or less permanent are grouped under the heading Equipment, while those which need to be renewed from time to time are considered as Supplies. PRINTING EQUIPMENT.

Bottles Camel's hair brush Io~nlarglng outfit (see Chapter

XVII). Graduates llt'atE'r for sepia bath Printing machine Safelights Scales Stirring rods (tubber) Thermometer (all glass)

Developer heater Hydrometer Mezzo plates (ground celluloid) Printing frames 路 Print paddles (rubber) Print washer Timer Tinting masks Vignetting frames

Trays

Trimming board Work tablt'

Bottles for solutions present a neater appearance if of uniform size. To secure permanent labels on

EQUIPMENT AND SUPPLIES

them, use water proof drawing ink and good thin white gummed paper. After the labels are stuck on, go over them with a size of thin glue or gelatine and allow to dry overnight. Then give them a coat of good varnish covering at least a half inch of margin around the paper. Use wide mouth bottles for storing dry chemicals and narrow ones for liquids. For the potassium bromide solution a dropper bottle is necessary. Graduates.-A number of graduates will be found useful, varying in capacity from 60 minims to a quart, or if the metric system is used, from 10 cubic centimeters to a liter. The figures and marks on the graduates should be engraved or etched since the moulded ones are difficult to see in the subdued light of the printing room while painted ones soon rub off. Printing Machine.-There are many types of printing machines on the market, varying from a simple box affair that rests on the table to the expensive projection machines with or without automatic focus. In the larger studios this latter type is gradually replacing other kinds, as the prints made by projection instead of by contact, can be made in any desired size and in a minimum of time. An explanation of this machine will be given in Chapter XVII on Projection Printing. There are several prime qualifications for a good printing machine-thoro ventilation, speed, convenience and ease in dodging and vignetting. Faulty ventilation is apt to result in the overheating of negatives with consequent injury to paper emulsions. For C'ase in vignetting, some arrangement for raising and lowering the ground glass is a decided convenience. Especially if much commercial work is to be handled. it i$ more satisfactory to have a number of lower pow-

PHOTOGRAPHIC PRINTING

er lights instead of a few 1arge ones~ It is then possible to control the light on certain portions of the negative by turning out those that are not needed. Home-made machines are easy to construct and will be found to· do very satisfactory work. (Figure 5.)

•

Figure 5

Home-made Printing Machines.

The printing surface should be about 15" square and the height of the box 12". Ventilation is secured by a row of holes on the sides and bottom, shielded so that direct rays of light do not escape. Four 75watt white lights are used and one 15-watt ruby light. A ground or flashed opal glass is inserted 1!" below the plate glass, preferably made adjustable for height. Switches are arranged at the side. If the printing lid is made in t'vo sections, as shown in Figure 16, the upper portion can be closed down on the paper while it is being held in position with the han~d, which may then be · removed and the lower section closed. This closing should operate a switch turning on the lights. It is also so wired that the red light turns off when the white lights are on. (Figure 6.) Sockets for •

•

EQUIPMENT AND SUPPLIES

bulbs should preferably be placed on the side of the machine. The inside of the machine should be given two coats of good heat-resisting paint. Cardboard masks may be used to prtvent the exit of white light if there is no top and smallsized printing frames are being used.

Safelights.-No light is entirely safe for very sensitive emulsions if in sufficient volume to produce good illumination. The standard used for the Wratten Safelights, however, Figure 6-Wiring Diagram. may be considered safe for all practical purposes, the test being that an exposure of a dry sensitive emulsion at a distance of three feet for half a minute using a 16-candle power bulb, producEs no visible fog. (See Experiment 7). These safelights are provided with interchangeable glass of different shades for the various plates and papers and are designed to give the maximum of safe i'llumination. For all ordinary developing papers, the light yellow should be used, as it gives an abundance of nonactinic light for judging the process of development, and it is not hard on the eyes. Enlarging paper is best developed by the aid of the orange safelight, while for opals, transparencies, and doretypes, the ruby light is best. Two or three small safelights at convenient points over the sinks are better than one large one. These

PHOTOGRAPHIC PRINTING

should be supplemented for general illumination by indirect safelights near the ceiling in the center of the room, enclosed in a box with an opening at the top. If two or three fair-sized bulbs of different densities are connected on independent switches, then the type may always be used which gives the greatest amount of safe illumination for the work at hand. A white light, protected by a wire guard, such as used in garages. may be attached to a long cord and have the wire frame covered with black paper except at the end. This will prove a great convenience in judging the proper depth of prints in the fixing bath, finding lost articles, etc. Scales.-Either the avoirdupois or metric weights may be used. Most studios use the avoirdupois altho these are rapidly being displaced by the metric in many lines of business and science. A few photographers sti'll cling to the apothecary system but since practically all photographic chemicals are sold under the other system, it is more convenient to use the avoirdupois. Two scales or balances will be necessary-one to weigh in grains or grams, and larger ones for fractions of pounds or kilograms, for hypo and other similar chemicals. Trays.-Enameled trays are very satisfactory, especially for developing. If the enamel becomes cracked or chipped, however, a coat of acid proof paint must be applied or prints may show iron spots and other defects. Oversize 8x10 trays that wi'll take 7xll prints, and llx14 trays are the usual sizes needed. Rubber and glass trays are suitable but break easily; porcelain trays are perhaps best but very expensive. The larger fixing and washing trays may be constructed of wood at less expense and will answer all prac-

EQUIPMENT

AND SUPPLIES

tical purposes. They should be perfectly tongued, grooved and mortised together, and then fastened with brass screws. The trays should next receive a heavy coating of roofing pitch (hard tar) or three coats of acid proof paint. The tar fills up the cracks better and causes no appreciable effect on the prints in the fixing bath or washing water. Other items of equipment will be discussed as they are needed in the various printing processes. PRINTING SUPPLIES.

With the exception of the stock of printing paper which shou'ld be kept in a dry place free from chemical fumes, the other supplies listed may be stored in the printing room, as they are used principally in vignetting, dodging, and blocking. Binding strips Cotton, absorbent Glue 路 Onion skin tissue paper Opaque Opaque brush Painter's sand Post-office paper Printing paper CHEMICAL SUPPLIES

Chemicals should be purchased in usable quantities and stored under favorable conditions or they are likely to deteriorate before being used. The amounts suggested are intended as a guide in determining the proportionate quantities with which to stock a small studio. Those in the first column are the more necessary, the others being used only occasionally.

36 5 5 1 25 i 1 l

PHOTOGRAPHIC PRINTING llbs. lbs. )b. lbs. lb. Lb. lb.

1 oz. 5 lobs. 1 lb. 1 lb. 5 lbs.

Aeetic acid (28%) Alum (potash) Hydrochinon Hypo Metol Potassium bromide Potassium ferricyanide Silver nitrate Sodium cai'bonate (powdered) Sodium chloride Sodium sulphide Sodium sulphite (powdered)

1 gal. Alcohol, denatured ! lb. Ferric chloride l doz. 15-grain vials, gold chloride 1 lb. Hydrochloric acid 1 oz. Iodine crystals (路resublimed) 1 oz. Mercuric chloridet J.. I.b. Potassium cyanidei 2 lbs. Potassium dichromate 4 oz. Potassium iodide 4 oz. Potassium sulphocyanide 5 Ibs. Sulphuric acid

Note :-If platinum, carbon, and other pictorial processes a1路e to be used, other chemicals wi11 need to be added. Preservation of Chemicals.-Many chemicals are affected by the oxygen, moisture. and carbon dioxide of the air. Metol, hydrochinon, and sodium sulphite are examples of chemicals that are easily oxidized, the latter being readily changed to sodium sulphate. Such substances should be kept in well stoppered bottles, or in covered tin cans, in a dry place. Other chemicals as potassium carbonate, sodium sulphide, and sodium carbonate are very susceptible to moisture. Sodium su1phide, especially, has such a strong affinity for water that it quickly deliquesces unless carefully protected from the air. It is best preserved as a strong stock solution. Sodium hydroxide and other similar chemicals take up carbon dioxide from the air and are more or less converted into the corresponding carbonates. Hypo keeps well in the open. A safe rule, however, is to keep all chemicals in air-tight bot1 These chemicals are extremely poisonous and should be kept in fluted bottles so that they may be readily distinguished in the dark.

EQUIPMENT AND SUPPLIES

ties or cans in a dry place. Many may be kept in the original containers. If possible a smal'l room should be set aside for the weighing of chemicals and mixing of solutions so that the dark room will not be contaminated with chemical dust. Much of the trouble in the printing room may be traced to chemical dust and fumes in the air. FINISHING ROOM EQUIPMENT Air brush outfit Dry mounting press Embossing board and wheel Ferrotype plates 100 Flattening cards, 8x10 100 Flattening cards, 7xll 25 Flattening cards, 1lx14 Framing outfit French cuTVes

Glass cutter Pen-etcher Press (for flattening prints) Print dryer Ruling pen Spotting brushes Triangle Trimming board

The spotting brush and trimming board are indispensable. As many of the other articles should be added as the kind of work done requires. A trimming board with iron bed is more durable and less liable to get out of true. It should be at least 15" square. When possible, printing and finishing 路 rooms should eaeh have a good trimming board. The air brush outfit consists of air brush, carbon dioxide pressure tank and reducing valve, the tanks being the same as those used in soda fountains. They may be rented from bottle filling works and returned when the gas is exhausted. The necessary equipment for framing pictures consists of moulding, sander, miter box, saw. hammer and nails. The miter box should be capable of being used for holding the moulding both for cutting and

•

38 I

PHOTOGRAPHIC PRINTING

for nailing. There should also be a supply of corrugated picture backing, a roll of good backing paper, and an assortment of screw-eyes, hangers, and picture wire. Picture glass may be obtained most economically by the box. A press as illustrated in Figure 7 is convenient for pressing prints between the flattening cards. These should be of heavy cardboard. The print dryer is not necessary unless one is doing amateur finishing. Fer. rotype plates, triangles, curves, ruling pens, and Figure 7 Flattening Press. a dry mounting press will be necessary if much commercial work is to be attempted . •

•

FINISHING SUPPLIES . •

To be added as needed: Cotton, ahso~bent Erasers, artgum Erasers, kneaded rubber Folders Lantern slide bindin·g strips Mounts

Opaque Sponges Spotting colors (card of four)

Blotters, Photo-finish, 18"x24" Carbo~ pencil India ink Lamp ·b lack Oil colors Photo coating powder Sepia color Water colors Waxing solution

Folders should be classified as to size, shape (oval or square), and color (sepia or gray), so that the ones needed ~ay be easily found. It is not advisable to stock up with many, as styles change so often.

EQUIPMENT AND SUPPLIES

Colors.-Oil colors, water colors, and air brush colors, while not absolutely necessary, are a valuable addition to one's equipment if proper use can be made of them. Any worker at all interested in the artistic end of photography will want to become proficient in their use.

CHAPTER IV.

ELEMENTARY CHEMISTRY. Purpose.-The aim of this chapter is to give to the photographer who has not had the advantage of any study in chemistry, a summary of the more important chemical phenomena, especially in their relation to photography. A careful study路 of this chapter will not only make more clear the explanations given later, but will enable the worker to gain a better understanding of his daily work. He is conscious of innumerable changes taking place in his solutions, prints, papers, and other materials. Paper exposed to the light rapidly turns dark; developer is soon oxidized by the air and turns brown; crystals of sodium sulphite exposed to the air for a considerable time lose their transparency, breaking down into a mass of sodium sulphate. It is the aim of chemical science to investigate and attempt to explain these various changes and transformations. Physical and Chemical Changes.-For simplicity it may be well to start with one of the most common of substances-water. If a drop of water is divided into the smallest possible particles, it is still water. If heated, it becomes steam; if cooled, it turns to ice; but in either case, it remains water. These changes are known as physical changes, meaning any change where the form is altered, but not the identity. The smallest particle of a substance that can still retain the characteristic properties of that substance is known as a molecule. If a direct electric current is passed thru water to which have been added a few drops of sulphuric acid

ELEMENTARY CHEMISTRY

to make the water a conductor, it will be noted that two gases are liberated--oxygen at the pole where the current enters and hydrogen where the current leaves the solution. Thus it is seen that water can be broken up into two substances. This process is known as a chemical change, since the identity of the substance has been altered. Any substances such as water or salt (sodium chloride) which are made up of two or more simpler substances in chemical combination are known as compounds. Water is a compound since it is a combination of the gases--oxygen and hydrogen; table salt is another, being made up of sodium, a metal, united to chlorine, a gas. Most substances used in photography are chemical compounds. Elements.-Some substances as iron, gold, oxygen, and hydrogen, no matter how finely they are broken up, cannot by any known means, be resolved into simpler substances. These are called elements. There are about eighty known elements but the number is constantly increasing as new ones are being discovered from time to time. No matter how powerful the chemical reagents used, nothing can be obtained from iron but iron, nothing from hydrogen but hydrogen. As the science of chemistry advances and methods of chemical analysis are better understood, it is quite possible that many of these so-called elements will be found to be really compounds which may be resolved into simpler substances. Atoms.-Water was seen to be broken up into two of these elements-hydrogen and oxygen. The smallest mass of an element that can take part in a chemical change is called an atom. All atoms of the same substance may be considered to be exactly alike, having

42 ·

PHOTOGRAPHIC PRINTING

the properties of that element but differing from all other elements. 1 Atomic Weight.-If the gases oxygen and hydrogen, obtained by the electrolysis of water, as already mentioned, had been measured and weighed, it would have been found that the volume of hydrogen was exactly twice that of oxygen but that the oxygen weighed eight times as much as the hydrogen. It is obviously impossible to weigh individual atoms and molecules but it is believed that equal volumes of gases contain equal numbers of molecules. So if one volume of oxygen is eight times as heavy as two of hydrogen, then one atom of oxygen is sixteen times as heavy as one atom of hydrogen. For convenience, the weight of the hydrogen atom is given as one and is taken as a standard in comparing with other elements. The atomic weight of an element, then, is a number that expresses how many times the atom is as heavy as the hydrogen atom. Thus the atomic weight of oxygen will be 16, iron 56, sodium 23, and so on. Molecular Weight.-If the atomic weights of any substance are added, there is obtained the molecular weight, or how many times the molecule is as heavy as the hydrogen atom. Since the molecule of water is composed of two atoms of hydrogen and one of oxygen, or 2+16, then 18 is the molecular weight of water. Formula.-Certain symbols are used to denote the atoms of the various elements. 0 means an atom of 1 This hypothesis may not be well founded, •as many investigators believe that changes may be taking place in the elements themselves; also that .many chemical phenomena are perhaps more easily explained by the ionization hypothesis. However, the above statement is sufficient for our present purposes.

ELEMENTARY CHEMISTRY

"43

oxygen, Cl stands for chlorine, H for hydrogen, Fe (ferrum) for iron, etc. When any atoms come together to form a molecule as in the case of water, H 20, the combined symbols are called a formula} and bear the same relation to the compound that the symbol does to the element. H 2 0 then means that two atoms of hydrogen are combined with one atom of oxygen to form one molecule of water. Properties of Matter.-There are several other properties of matter that must also be considered. According to the Law of the Conservation of Energy, matterÂˇ can neither be created nor destroyed. It has also been found by innumerable experiments that when two substances combine to form a new substance, they always do so in certain definite proportions. For example, in the for.mation of water, H 2 0, eight parts by weight of oxygen will always combine with one part of hydrogen. It is also known tha-t there are certain substances that are able to combine in two or more definite proportions. So oxygen and hydrogen can also combine in the proportion of 16 to 1 by weight, to form hydrogen peroxide, H 2 0 2 â&#x20AC;˘ This capacity of any element to unite with others is known as valence and is expressed in terms of comparison with the unit hydrogen. Elements which combine in more than one proportion have more than one valence. This variation in combining power will help explain oxidation and reduction. Reactions.-(See Experiment 1.) When two or more substances combine or react under suitable conditions to form an entirely new substance, the reaction 2 The term formula as used in this connection must not he confused with the same word commonly used in photographic expressions as developing formula, etc.

PHOTOGRAPHIC PRINTING

is most conveniently expressed in the form of an equation, using the chemical formulae. Silver nitrate and sodium chloride together produce silver chloride which is generally used to ripen a sepia bath. This reaction in the form of an equation is as follows: AgN0 3 + NaCl = AgCl + NaN03 108+14+(16x3) + 23+35.5 170 + 58.5

Ag is the symbol for silver. N " " " " nitrogen. 0 " " " " oxygen. Na " " " " sodium. Cl " " " " chlorine.

108+35.5 + 23+14+(16x3) 143.5 + 85 Its atomic weight is,,. 108. -14. " " " " " " " 16.

" "

" 23. " 35.5

Rightly interpreted, this equation expresses the following things:-(a) Silver nitrate and sodium chloride combine to form silver chloride (a white curdy precipitate, insoluble in water). (b) Silver nitrate is formed of 1 atom of silver, 1 of nitrogen, 3 of oxygen; sodium chloride of 1 atom of sodium and 1 of chlorine; silver chloride of 1 of silver and 1 of chlorine; and sodium nitrate of 1 of sodium, 1 of nitrogen, and 3 of oxygen. (c) Each atom and each amount on the left side of the equation is accounted for on the right side. They must always balance. (d) The molecular weight of each compound is obtained by the addition of the atomic weights of the individual elements forming it. (e) The molecular weights of the silver nitrate and sodium chloride which react to form silver chloride and sodium nitrate are indicated. These are proportional to the amounts taken of those substances. That is, 170 parts by weight of silver nitrate will exactly combine with 58.5 parts of sodium chloride to form 143.5 parts of silver chloride and 85 parts of sodium nitrate. These amounts may be considered as in ounces, pounds, grams, or any other unit. Therefore an equation such as this provides a means of determining how much of a substance to use

'"'

ELEMENTARY CHEMISTRY

to combine with a given amount of another substance. For example, to find out how much sodium chloride will exactly combine with 10 grains of silver nitrate. we have a case of simple proportion. Molecular wt. AgN0 3 17t).

Molecular wt. Amount taken Amount formed NaCl .. AgN0 3 NaCl 58.5 .. 10 X 170x 585 x 3.44 gr. of sodium chloride.

To find the amount of silver chloride formed by 10 grains of silver nitrate combining with the proper amount of sodium chloride, the method is the same. 170 : 143.5 170x X

10 :X 1435 8.5 grains of s-ilver chloride formed.

In considering the equations which occur from time to time in the text, it must be remembered that an equation represents what actually occurs as has been worked out by analysis or otherwise. All substances will not combine or react and cannot be used in this way.

Solutions.-Solvents are substances such as water in which other chemicals are dissolved. Solutions are made by dissolving some chemical (the solute) in a solvent. Salt dissolved in water forms a solution. A saturated solutitm is a solution made by dissolving as much of a chemical as is possible at that temperature. A small amount is usually added in excess of that which will dissolve, in order to make sure that the solution is saturated. When a saturated solution lowers in temperature, there is a tendency for crystals to form. Many substances when crystallizing out of solution take up a definite quantity of water which is necessary to the shape of the crystal. This water which is held in

PHOTOGRAPHIC PRINTING

chemical combination is known as water of crystallization. An example ofÂˇ this is found in hypo, used for fixing prints. Its formula, Na2 S2 0,; 5H 2 0, means that five molecules of water are held in chemical combination with each molecule of Na2 S2 0 3 â&#x20AC;˘ Deliquescence and Efflorescence. - Substances which when exposed to moist air take up enough moisture to become wet are said to be deliquescent. Other substances as sodium carbonate crystals if exposed to air in a dry place lose their water of crystallization and become covered with a dry powder. These substances are said to be efflorescent. ACIDS, BASES, AND SALTS.

These are the three most important classes of compounds with which the photographer is concerned, so some knowledge of their properties is necessary for their intelligent use. Some photographic solutions must be acid to work satisfactorily, others must be alkaline. The simplest test for studio work is the use of litmus paper which may be obtained in small tubes, containing 100 strips of either red or blue. If a strip of the red is placed in an acid, it will remain red, but if placed in an alkali it will turn blue. In the same manner, a strip of blue placed in an acid immediately turns red, but in analkali, it will remain blue. If a solution is neither acid nor alkaline, the color will not change at all. The following graphic method is given as an aid in remembering the action of the two colors of litmus paper. AciD Base (or alkali) Re lue Acids.-Acetic, oxalic, nitric, sulphuric, and hydrochloric acids are the most important ones used by

ELEMENTARY CHEMISTRY

the photographer. An acid is a substance (a) that in water solution will tum blue litmus paper red, as described above; (b) that in solution in water will have a sour taste, as in the case of vinegar, which contains acetic acid; (c) that reacts vigorously with bases and many other substances; (d) that contains one or more hydrogen atoms that may be replaced by a metal to form a salt; (e) that in water solution will yield hydrogen ions. The vigorous action of an acid reacting or combining with other substances is illustrated by dropping a few pieces of gram.Ilated zinc into a beaker of hydrochloric acid. The zinc will soon disappear and a gas, hydrogen, will bubble up. If this gas comes off rapidly enough it may be ignited, giving a small report or explosion as it combines with the oxygen of the air to form water, H 2 0. What actually takes place when the zinc and hydrochloric acid react is expressed by the equation. 2HCl+Zn=ZnCl+H 2 路The hydrogen of the acid is replaced by a metal, zinc, to form a salt, zinc chloride, with the liberation of hydrogen gas. An acid dissolved in water always contains hydrogen ions. An ion is an atom or group of atoms carrying an electric charge. The more it is dissociated, with the formation of the hydrogen ions, the stronger is the acid. Nitric and hydrochloric acids are examples of strong acids ; acetic and oxalic acids of weak ones. Bases.-Bases are to a certain extent the opposites of acids. When dissolved in water, they are said to have an alkaline reaction since they tum red litmus paper blue. They may be formed in different ways, one being by the action of a metal like sodium, on water.

PHOTOGRAPHIC PRINTING 2Na+2H 2 0=2Na0H +H 2

This forms sodium hydroxide, commonly known as caustic soda, with the liberation of hydrogen gas. In water solutions of bases, hydroxyl ions are formed. In sodium hydroxide, NaOH, the OH portion is the hydroxyl group of atoms carrying the negative charge. Neutralization.-Acids and bases react to form salts and neutralize each other.

+- + HCI+NaOH=NaCl+ H 2 0 Here the hydrochloric acid and sodium hydroxide have combined to form one of the best known salts-sodium chloride (table salt) and wat~r. The H ion of the acid with a positive charge is neutralized by the hydroxyl (OH) group of ions with a negative charge. The significance of this to the photographer is that a solution which is too acid may be neutralized, forming neither an acid or base, by adding the proper amount of a base, and vice versa. All salts, however, are not neutral. For example, sodium carbonate, Na 2 C03 , altho a salt, liberates a small number of hydroxyl ions by its action with the water and has a slightly alkaline reaction. Salts.-A salt then may be formed by neutralizing an acid with a base as shown above, or by replacing part or all of the hydrogen of an acid with a metal, as in the action of hydrochloric acid on zinc, already discussed. Zinc chloride is the salt formed in that case. Among the more common salts used in photography are the nitrates as silver nitrate, AgN0 3 ; the chlorides as sodium chloride, NaCl; the sulphites as

ELEMENTARY CHEMISTRY

' 49

sodium sulphite, Na2 S03 ; the carbonates as sodium carbonate, Na2 C03 ; and the sulphates as sodium thiosulphate (hypo), Na 2S2 0:i 5H 2 0. Sodium sulphate, for example, is formed by replacing the hydrogen of sulphuric acid, H 2S04 , by sodium to form Na2 S04 • In sodium sulphite, the sodium replaces the hydrogen of sulphurous acid, H 2S03 , and forms Na 2S03 • In general, acids having the prefix hydro and ending in ic form salts ending in ide, as sodium chloride from hydrochloric acid. Other acids as sulphuric ending in ic form salts ending in ate as sodium sulphate. Acids in ous as sulphurous, having less oxygen than those ending in ic form salts ending in ite as sodium sulphite. Oxidation and Reduction.-Other chemical reactions which are very important in photography are oxidation and reduction. One of the most common examples of the former is found in the case of sodium sulphite, Na2 S03 • If the sulphite is exposed to the ail·, especially in a damp place, it soon turns to sodium sulphate and is then useless as a preservative. Na2 S03 +0=Na2 S04 Such a process is known as oxidation. (See Experiment 2.) It is to prevent oxidation that stock developing solutions should be kept away from the air in full corked bottles. Chemicals that give up oxygen readily are termed oxidizing agents. Other substances have a tendency to remove oxygen and the halogens as chlorine and bromine from the compounds in which they occur. Such substances are called reducing agents. Developing reagents are of this class. The developer reduces or combines with the chlorine in the silver chloride of the paper that has been affected by the light and leaves metallic silver. This process is called reduction.

路50

PHOTOGRAPHIC PRINTING

. Note :-The student if further interested should consult some good elementary chemistry text-book for general principles, and the following books for information dealing moredirectly with photographicchemistry: Flint: Chemistry for Photographers Hasluck: Photographic Chemistry Townsend: Chemistry for Photographers Eastman Kodak Co.: Elementary Photographic Chemistry.

CHAPTER V. PREPARATIONS OF SOLUTIONS. Many amateurs and some professional photographers prefer to purchase chemicals in a condition ready for use as soon as water is added. This method, however, is not only needlessly expensive, but more important, it gives the photographer no opportunity to vary the ingredients to meet local conditions, or to get the effect desired at a particular time. Preparing one's own solutions will be found to be much more satisfactory in every way. Systems of Weights and Measu.res.-In photographic practise, solids are weighed and liquids are measured either by the United States standard of weights and measures, or by the metric system. The former is more commonly used, altho those who are familiar with both find the metric system very much simpler. United States Standard Weights and Measures.___; Chemicals are usually bought and sold by this system. Avoirdupois Weight.路 Metric equivalent. Pound (lb.) l

Ounces (oz.) 16 1

Grains (gr.) 7,000 437.5

Grams (g.) 453.60 28.35 .065

Fluid Measure.

Metric equivalent.

Gallon Quarts Ounces Drams Minims (qt.) (oz.) (dr.) (min.) (gal.) 4 128 = 1,024 = 61,440 1 1 = 32 256 = 15,360 1= 8= 480 1 = 60

Cu. centimeters (c.c.) 3,785.44 946.36 29.57 8.70

.082

PHOTOGRAPHIC PRINTING

Metric System.-This is used in all scientific work in this country and almost exclusively in other countries. Since such values as hectograms, deckograms, etc., are seldom used, only those needed are given here. Measures of Weight. ~ilograms

Gra.ms

(ikg.)

(g.)

Avoirdupois Equivalent.

Milligrams (mg.)

1,000 = 1,000,000 1 1,000 1

Measures of Volume. Liter 1

( 1.)

2.20 lb. 15.43 gr. .0154 gr.

U. S. Equivalent.

Cubic centimeters ( c.c.) 1,000 1 -

33.81 oz. 16.20 min.

Conversion Table.-For practical purposes, the photographer will find the following table of conversion reasonably accurate. 1 ounce (avuirdupois) 1 ounce (liquid) 1 gallon 1 gram 1 kilogram 1 cubic centimeter

28 30 4 15 2 16

grams cubic centimeters liters grains pounds minims.

Formulae in this book will be given in both systems. However, when one is converted into the other, the numbers are not always convenient to work with. For instance, 32 oz. water = 946 c.c. In this case, if the formula were made up to read, Water........... .lOOO c.c., or 1 liter, with the other ingredients in proper proportion, it would be more satisfactory. Consequently. the formulae given in the following pages must be weighed and measured entirely in one system or the other, as the amounts given in the T/nited States and metric systems are not necessarily equivalent. Temperature.-For convenience, the temperature is given both in Fahrenheit degrees (F.) and in the equivalent Centigrade degrees (C.).

PREPARATIONS OF SOLUTIONS

Purity of Chemicals.-There is no guess work in the results obtained in chemistry. Chemicals under identical conditions always react in exactly the same way, always producing the same result. In order that conditions may be similar,. it is imperative to have chemicals which are pure and uniform. Inferior brands often contain impurities, while even reliable ones deteriorate unless proper attention is given to their storage. Common lmpurities.-Sodium sulphite often contains as an impurity sodium sulphate which decreases its power to preserve the developer. Hypo may contain sodium sulphite. If so, the solution as made up will not fix as many prints as it should. Alum has sodium sulphate and ammonium sulphate as possible impurities with the effect of a decrease in its hardening action. Developing agents may be partly oxidized with a tendency to fog, and have decreased developing power. If the water is pure, the clearness of the solution after it is mixed will be somewhat of a criterion as to the purity of the chemicals. 路 Water.-The purest forms of water are distilled water, rain water, and snow and ice water. Often when a formula does not work satisfactorily, the use of distilled water will remove the seat of the trouble. Rain water if collected from the first fall may contain many impurities from the dust in the air or from the roof. Water caught from iron and tin roofs is often unsuitable. In general, the regular city water as used for drinking will be found suitable for photographic use. 1t may, however, contain two types of impurities: (a) Salts such as bicarbonates, chlorides and sulphates of sodium, potassium, calcium, magnesium, and iron. These compounds are dissolved or taken into suspension as the water runs over the ground and percolates thru the soil or rocky strata. (h) Suspend-

PHOTOGRAPHIC PRINTING

ed matter such as clay, and minute organic forms of plant and animal life. Water which has been put thru a commercial filter plant may also contain such impurities as aluminum sulphate and chloride of lime which have been added to cause sedimentation and to kill germs. Tests for Purity of Water.-A pale brown color in the water may indicate o路rganic matter. It is liable to cause stains on photographic paper. The presence of calciumandmagnesium is shown by a white precipitate obtained by adding a solution of ammonium oxalate. These metals may be precipitated as insoluble oxalates when making up a ferrous oxalate developer or other solution containing a soluble oxalate. If sulphates are present, the addition of barium chloride will throw down a white precipitate, barium sulphate, insoluble in water and in hydrochloric acid. Such substances as calcium and magnesium cause permanent hardness of water. Water containing chlorides will form a-white precipitate insoluble in water and dilute nitric acid, if silver nitrate is added. This will happen in photographic solutions containing siver nitrate. 路 Effects of Impurities in Water.-Carbonate in the water may make necessary the cutting down of the amount of sodium carbonate added to the developer. Chlorides and bromides may be present in sufficient quantities to make necessary the addition of little or no potassium bromide as a restrainer. Calcium salts may combine with sodium bisulphite and similar preservatives to form a precipitate (calcium sulphite) which will settle out on standing, thus lessening the amount of available sulphite. Animal and vegetable matter if not removed may coagulate and settle out in the solution as a sludge. Iron compounds are often the cause of blue-black spots on prints. Purification of Water.-(See Experiment 3.) (a) Distillation is the term used to denote the va-

PREPARATIONS OF SOLUTIONS

porization of water or any other liquid, and the subsequent condensation of the vapor. In Figure 8 is shown the apparatus commonly used for this purpose. This

Figure B.-Distillation of Water.

method of purification should be used when the water is not suitable for photographic use. Distilled water may usually be obtained at automobile battery stations. (b) The boiling of water will. cause the coagulation of organic matter; change certain salts to an insoluble condition so they will settle out; drive out dissolved air and so cause less oxidation of the developing agents ; and remove dissolved gases as hydrogen sulphide and carbon dioxide. In the latter case the boiling decomposes any calcium carbonate in the water and drives oft" part of its carbon dioxide, leaving the insoluble carbonate which forms the "scale" on kettles. The clear water can be poured off after the deposit settles. (c) Chemical treatment is resorted to in most commercial filter plants to remove organic and other impurities. Solution of Chemicals.-The rate of dissolving a chemical depends on (a) its solubility, (b) fineness, (c) temperature of the solvent, (d) rate of stirring, (e) amount already in solution, (f) amount of other chemicals already in solution. In most cases it is desirable to use warm water as this will hasten solution. Care must be taken, tho,

I;>HOTOGRAPHIC PRINTING

that it is not too hot or in some cases it may cause trouble. In dissolving hypo in hot water, there is a chance of sulphurization, while in the case of developing agents, more oxidation is likely to take place with a greater tendency to cause stain and fog. Anhydrous salts as the carbonates and sulphites of sodium should always be added to water while stirring. If, instead, water is added to these salts, a hard cake will be formed which is difficult to dissolve. All chemicals should be dissolved before using the solution. If only partly dissplved, it is not safe to 路use it on the theory that an additional amount will make up for the difference, for crystals are likely to get on the emulsion causing spots. Also, if one chemical remains partly undissolved, the solution will be weaker in one Qr more respects. For instance, if the restrainer is only partly in solution, the accelerator may cause such rapid action as to produce chemical fog. Again, the developer may be so much restrained as to make it useless. Methods of Mixing Solutions.-The most usual method of determining the amount of chemicals needed for use in a given formula is by weighing and measuring. Reasonable accuracy must be used, for while an error of 3% is negligible for practical purposes it is not allowable for experimental work. Chemicals should be weighed on a small paper about four inches square, while a similar one should be placed on the other pan of the scales so that they will balance. Time is saved and accuracy increased, if instead of waiting for the pointer to come to rest at the center, observation is 路made as to whether it swings the same number of aivisions each side of the center. The two sides are then balanced. 路 The papers on which the chemicals are weighed should be rinsed off and thrown away after using. This prevents chemical dust from

PREPARATIONS OF SOLUTIONS

getting into the air and later causing damage. Graduates are marked off in ounces and drams or in cubic centimeters. In reading the amount of a liquid, its surface should be on a level with the eye. Since capillary attraction causes the liquid to be drawn up at the sides above the level at the center, the reading should always be taken at the lower level. For practical purposes, one drop equals about one minim. Using a certain number of drops of a solution is not a very accurate method however, as (a) drops vary in size with different liquids, and (b) the concentration of saturated solutions as of potassium bromide, varies with the temperature. Onedropat70째F. (21.1 째C.) would contain more of the salt than at 65째F. (18.3째C.). Greater accuracy is obtained when the chemicals are weighed. Hydrometer Test.-This method is used for mixing up chemicals to a certain specific gravity, as the hydrometer will give a definite reading of the density. However, it takes no account of impurities which may cause too high a reading of the strength. It is of special value in determining the amount of such chemicals as hypo which may have become moist or which contain water of crystallization. Stock solutions made by weight from very moist chemicals may have a high percentage of error. If high grade chemicals are used and are kept under proper conditions, it will be found more convenient in most cases to measure them by weight instead of by the hydrometer test. Percentage.-When a formula is given in percentage, it should represent the percent of the chemicals in the solution. This applies both to solutions of a liquid in a liquid and a solid dissolved in a liquid. For a 10% solution of liquids, take 1 ounce of the liquid and make up to 10 ounces of water (or 10 c.c. to 100 c.c.). In the case of solids there are several methods used to obtain the 10% solution:

PHOTOGRAPHIC PRINTING

(a) 1 oz. in 10 oz. water. (10 g. in 100 c.c. water.) (,b) 1 oz. in 9 oz. water. (10 g. in 90 c.c. water.) (c) 1 oz. in a little water and make up to 10 oz. (10 g. in a little water and make up to 100 c.c.) In (a) the amount obtained is a little over 10 ounces (or 100 cubic centimeters); in (b) a little less. As equal weights of different chemicals do not occupy the same volume, neither of these methods is much used by the photographer, tho a chemist might use method (b). (c) is commonly used in preparing photographic solutions. Since 1 ounce avoirdupois equals 437.5 grains, a 1% solution may be prepared by dissolving 4.37 grains in a little water and making up to 1 ounce by adding water. For a 5% solution multiply by 5 and make up to 1 ounce; for a 10% solution by 10 and so on. Use of Percentage Solutions.-Since a percentage solution indicates how many parts are dissolved in 100 parts of water, it may be used to advantage in preparing certain formulae by measuring the solutions rather than weighing the chemicals. For example, from a 10% solution of potassium bromide a formula calling for 15 grains can be readily prepared. Since in the avoirdupois system there are 437.5 grains to the ounce, a 10% solution will contain 43.75 grains. Then to obtain an amount containing 15 grains, take 481.: 5 of an ounce. This equals .34 of an ounce or about 2. 7 drams of the 10% solution. In the metric system the numbers are much easier to deal with. A 10% solution contains 10 grams of potassium bromide to 100 cubic centimeters, or 1 gram to 10 cubic centimeters. Then since 1 gram equals 15 grains, 10 cubic centimeters of the 10% solution will give the required amount. This use of a stock solution is especially desirable where only a small part of a grain is required, as most balances used by photographers are not sensitive to less than one grain.

PREPARATIONS OF SOLUTIONS

Dilution of Liquids.-ln diluting a solution a given number of times as four, add three times the amount of water, not four. For three volumes of water plus one volume of the liquid will give four volumes of solution which will be fou1路 times as dilute as at first. Often a strong acid must be qiluted to the strength called for in a ,given formula. For example, 28% acetic acid is the strength ordinarily used in photographic work. When making this from glacial acetic acid (99%) it is necessary to add 2.53 parts of water to every part of the glacial acid. The number of parts of water to be used may be found by either of the following methods: (a) In 99% acid there are 99 parts acid and 1 part water. In 28% acid there are 28 parts acid and 72 parts water, the difference in the parts of water in the two cases being 71. Therefore 71 parts of water must be added to dilute the 99% acid to 28%. That is, for every 28 parts of the 99% acid taken there must be added 71 parts of water. Then for 1 part acid, add fi of 71, or 2.53. Formulated as a rule it might be stated: The difference in the parts of water, divided by the percentage of the weaker solution, equals the number of parts of water to be added to each part of the stronger solution. (b) Or it may he figured on the basis of the strength of the acid. 99% acid is 3.53 times as strong as 28% acid. So to make it 3.53 times as dilute, enough water must be added to one part of the strong acid to make 3.53 parts of weaker acid. That is, 2.53 parts of water must be added. CAUTION.-When diluting such strong acids as sulphuric, the acid must always be poured slowly into the water. Never pour water on to a strong acid as the heat evolved is so great that liquid is likely to he thrown out of the container and cause injury. A convenient method of adding acid to water is by means of

PHOTOGRAPHIC PRINTING

a thistle tube which deposits the acid below the surface of the liquid. Filtration of Solutions.--Some solutions contain more or less suspended matter such as dust. impurities, particles of undissolved chemicals, etc., which may settle on the printing路 paper causing spots. These impurities may be removed: (a) By allowing the sediment to settle, and then pouring off the clear liquid. This process is satisfactory for the coarser particles and may be hastened by the use of hot water as this tends to coagulate the suspended matter. (b) By the use of filter paper in a glass funnel. This method is slow as the liquid comes thru drop by drop but it is quite efficient. However, as the solution is exposed to the air for some time it is more liable to oxidation. (c) By straining thru a fine-mesh cloth bag. If the chemicals are placed in this and suspended in the water, they will dissolve in most cases with but little sediment entering the solution. Stock Solutions are simply concentrated solutions to which more water must be added before use. The advantages of such a solution are that it (a) takes less storage space, (b) is less trouble than where solutions must be mixed from day to day, and (c) has better keeping qualities, as far as many chemicals are concerned. It must be remembered that only a definite quantity of a chemical can be dissolved in a given amount of water. This quantity can be increased in the case of developers by the addition of alcohol up to 10%. (See Chapter XI on Development.) If a considerable quantity of some chemical is dissolved, it may prevent the solution of others, added later. For instance, a large amount of sodium sulphite will prevent some brands of metol from going into solution whereas the metol would dissolve first and then the sulphite

PREPARATIONS OF SOLUTIONS

could be added. Again, certain chemicals may throw down others already in solution. In general, it is easier to keep a chemical in solution than to re-dissolve it afiter it has been thrown down. Storing of Stock Solutions.-Solutions should be kept from contact with the air. It is a bad practise to store developer in large bottles, for as soon as part of it is used, the remainder will become somewhat oxidized by the air in the upper portion of rthe bottle with a cons€quent tendency to cause fog. A better way is to pour the stock solution into several well-corked bottles, of such size that the contents of each can be used within a short time (two or three days) after opening. Still better is a method which will exclude the air at all times. A cylindrical tank is provided with a floating lid, paraffined or painted with acid proof paint. (See Figure 33 in Chapter XI for a similar arrangement.) This cover should be as large as will raise and lower easily and will remain on the surface of the liquid at all times, effectively excluding the air. In this way, solutions may be kept for a long time in good condition. A pinch-cock, clamping a short length of rubber tubing, gives a convenient way of drawing off the solution.

CHAPTER VI. PRINTING PAPERS. Printing papers are often known only by a generic name, a trade name, or even by the name of the manufacturer. Such names give no indication of the characteristics of the paper. Yet every different kind of printing paper is distinctive in its properties and gives prints which will vary in some particulars from those made from the same negative on any other kind of paper. Composition.-Most printing papers belong to two distinct grades but have similar characteristics. These are "chloride papers" and "bromide papers". The former having a slow emulsion are used for contact printing and the latter with a much faster emulsion for enlarging purposes. However, some modern enlarging papers are chloride papers, which tho slower give better gradations and blacks than the ordinary bromide papers. Printing papers consist essentially of a paper base on which is coated a sensitive layer called an emulsion which holds in suspension some silver salts as silver chloride or silver bromide. These silver salts are sensitive to the action of light and are so changed by its action that the developer is able to reduce them, removing the chlorine or bromine and leaving the black metallic silver which composes the image. DEVELOPING PAPERS.

Chloride Papers.-The manufacture of chloride papers is in general as follows. A suitable paper is

PRINTING PAPERS

obtained as a support for the emulsion, good grades of specially prepared paper free from all impurities being selected. This may have a sizing such as a "baryta" coa:ting to help keep the image on the surface. The emulsion, which must now be prepared, consists of the suspension of silver salts in some vehicle, usually gelatine. This is a complex substance which is obtained by boiling together bones, hoofs, and other animal parts, and belongs to that class of non-crystalline substances known as "colloids". In cold water it swells up and may absorb from :five to ten times its weight. If the temperature is raised to about 90Â°F. (32.2Â°C.), a good sample will absorb sufficient water to dissolve it and on cooling will set into a jelly-like mass. Prepa'ration of Emulsion. 1-The emulsion is prepared by soaking soft gelatine in distilled water and then heating and shaking until it is all dissolved. The necessary chloride salts such as ammonium or sodium chloride are sometimes added at this time and will soon be dissolved, or they may be added to the water at the same time as the gelatine. Other chemicals not absolutely necessary to the making of sensitive paper but dEsirable as preservatives and for increasing sensitiveness are usually added by the manufacturer. This viscous mixture is now taken to the dark room where there is added to it, a little at a time, with constant stirring, a solution of silver nitrate. AgN0 3 + NaCl=AgCI+ NaN0 3 The silver chloride, a white precipitate insoluble in water, is the material which is sensitive to light. The gelatine prevents it from settling and it is held in :finely suspended particles evenly distributed thruout the 1

PhotoÂˇMiniature No. 179: Photographic Emulsions.

PHOTOGRAPHIC PRINTING

solution. More sodium chloride is always used than the amount of silver nitrate requires in order to avoid any of the nitrate remaining uncombined. If there should be an excess of the nitrate, it may interact chemically with the gelatine and produce a deposit or fog when the paper is being developed. A greater excess of chloride is used in some brands of paper than in others, resulting in a difference in the manipulation necessary to secure similar tones. The emulsion is next removed to a cool place, still in the dark, where it should set as quickly as possible. Sometimes the emulsion is washed at this stage in order to free it from any unnecessary salts. This operation is carried out with running water in specially constructed washing tubs which keeps the shreds of emulsion in continual agitation. However, modern slow chloride emulsions are practically all unwashed. After being heated to melt the emulsion, it must be filtered and then cooled to about 90째F. (32.2째C.) when it is ready for coating on the paper, where it soon sets to a jelly. This when dried forms a smooth coating of gelatine containing the sensitive silver chloride. All of this process beginning with the addition of the silver nitrate to the sodium chloride is of course carried on in a room illumined by a safe light. A greater degree of sensitiveness is obtained in some papers by heating the emulsion for a longer time and to a higher temperature. Each time the emulsion is remelted, it tends to give a softer image and a greater degree of sensitiveness. In general, the more rapid the emulsion, the larger are the particles of silver salts with a lessening of the possible gradation. Bromide Papers.-These are essentially the same as the chloride papers except that potassium bromide is used instead of a chloride salt, with the result that the sensitive salt in the emulsion is silver bromide.

PRINTING PAPERS AgN0 3

silver nitrate

potassium bromide

KBr = AgBr

KN0 3

silver potassium bromide nitrate

Bromide papers are faster than chloride papers and are generally used for enlarging, altho under suitable conditions they make very good contact prints. The very fast bromide emulsions are used f01路 the making of dry plates. In the case of color sensitive plates, c::rtain dyes as erythrosine or sensitol violet are added to make them sensitive to yellow and red light. Emulsions are not always simple chloride or bromide but very often contain a mixture of the two, together with some iodide. PRINTING-OUT PAPERS.

The earliest printing paper, plain silver paper, was introduced by Fox Talbot about 1840. A smooth paper was simply coated with solutions of silver nitrate and sodium chloride. This is essentially the basis of modern P. 0. P. (printing-out papers), which may be toned with gold, giving a purple-brown image, or with platinum, giving a warm black color. The tendency of the image to appear sunken instead of remaining on the surface, resulted a few years later in the introduction of albumen paper. In this case albumen was the vehicle which carried the silver salts. These papers gave a brilliant image and when toned with gold or platinum were quite pleasing. However, albumen prints exhibited a tendency to fade in a few years. Most of the prints in the family album of a generation ago were of this type. These papers were followed by other printing-out silver chloride papers in which the vehicle carrying the silver salts was either collodion or gelatine. The first of these were known as collodio-chloride papers, e. g., Aristo, Jr.; and the second class as gelatinochloride, e. g., Solio.

PHOTOGRAPHIC PRINTING

Papers of this type differ from developing chloride and bromide papers in that the image becomes visible while printing. They contain an excess of sid.ver nitrate over the sodium chloride or potassium bromide and therefore could not be used for developing under normal conditions. The silver salts are generally assumed to form some complex organic silver compound with the binding material-albumen, collodion, or gelatine-which on exposure to the light darkens and gives the characteristic reddish tint of proof papers. These papers are usually toned and then fixed in hypo to remove any remaining sensitive salts. One type of these-the self-toning papers-need only to be put in a salt bath, to give them a better color, then washed and fixed. Other Printing Papers.-The more pictorial papers, as carbon, platinum, etc., will be briefly discussed in Chapter XX. Emphasis has been given here to those papers and processes in most common use.

CHAPTER VII. CHOICE OF PRINTING PAPERS. A great many types and varieties of printing papers are available for the modern photographet". Instead of merely learning mechanically a method of working some one paper, he should become familiar with the principles of printing manipulation and he will then have at his command almost unlimited possibilities in producing that which is best in photography. For the muJtiplicity of papers represents a valuable means of producing not only distinctive work but also of getting that which is best, technically, and artistically, from every negative. Good craftsmanship in the use of paper may produce a variation in the color, tone, and quality of pictures which compare favorably with those made with the brush and oils. Paper Stock and Surface.-Photographic paper emulsions are usually coated on a white or buff stock, tho occasionally on a light cream base. If the printer desires, he can make up some kinds of paper himself and then is not limited as to color and texture of the stock. Printing papers range all the way from glossy, thru semi-matte, smooth matte, slightly rough, rough with sheen, to very rough. If something out of the ordinary is wanted, there are papers with silk, linen, and canvas surfaces, as well as emulsions on tissue, parchment, and canvas. Suitability.-ln general, large heads, especially character studies of older people, look best on rough matte papers. This surface is also appropriate for enlarged views where breadth and atmospheric effect are desired. However, small prints are often made on too

PHOTOGRAPHIC PRINTING

smooth a paper and medium sized ones on too rough a surface to be most effective. Dead matte papers are disappointing for many subjects, for when drying, the image seems to sink down into the emulsion, causing the print to lose its richness, the highlights to become dull, and the shadows to flatten. This is especially true in the case of the small work done for amateurs, which is usually most satisfactory if printed on a semi-matte or a velvet surface. Semi-matte papers are also often best for groups, as the heads are small and a rougher paper might give an objectionable texture to the skin and make more indistinct the eyes and other features. For the great majority of work, a smooth matte surface paper or one that is slightly rough with a sheen is most satisfactory. A number of prints from different types of negatives and subjects in a wide variety of papers and. in different tones will prove valuable for reference. Color.-Color suggestiveness, as well as a proper selection of papers of suitable texture and contrast, generally enhances the artistic effect of the final result. Prints of a warm black color, especially if made on a slightly rough buff paper or on smooth ivory-tinted stock. have a peculiar richness and are productive of very beautiful effects. An occasional print in the predominating color of the subject is very attractive and breaks the monotony of black and white or sepia prints. In the case of a home portrait taken against a garden background, a print in srreen would suggest the atmosphere, light, and color of the surroundings. Firelight studies are very good in a suitable shade of red. using a paper of the right contrast so that the highlights on the face have only a very slight tint. An evening view or a snow scene gives the best effect if printed in blue. However, the

CHOICE OF PRINTING PAPERS

introduction of color should be reserved to emphasize the value of a particular piece of work. The color may be secured quite satisfactorily by toning ordinary developing papers, but for variety, depth and richness of tone, the carbon process is unequalled. Color gradations will be more truthfully rendered if a suitable foundation is laid by the use of color sensitive plates and filters in the production of the negative. TONAL VALUES.

The ideal print, technically, is one that correctly reproduces in the proper relation and depth, all the variations of light and shade in the original subject. However, because of unsatisfactory lighting conditions, it is sometimes better to choose printing papers that give values of different range and seale from those of either the subject or the negative. Otherwise, the result will not be pleasing from an artistic standpoint. In order to select the right kind of paper for a given negative, it is necessary to know something of the comparative abilities of various plates and papers to represent each tone of the original by a corresponding tone in the finished print. Scale of Contrast in Lighting.-Any object which may be photographed has a range in tone values due (a) to the amount of illumination falling upon it, and (b) to the ability of the different parts of it to reflect light. Objects differ very much in their reflecting power-snow reflects perhaps 80% of the light falling upon it, while black velvet may not reflect more than 2%. In an ordinary studio lighting, the lightest part of the clothing as the collar may reflect 50 times as much light as a black coat in the deepest shadow. In an outdoor view, bright objects in the sunlight may reflect 200 or more times as much as the darkest ones in deep shadow.

PHOTOGRAPHIC PRINTING

This total variation of the reflecting ability of different portions gives the scale of contrast-or more commonly, contrast-of the lighting. In the case of a line lighting where the scale of contrast might be as much as 100 to 1, the lighting would be known as a "contrast lighting", whereas a scale. of 10 to 1 would be considered a very "flat" or soft lighting. Ordinarily, the contrast values of the lighting should be as great as can properly be translated thru the negative to the print. Only in this way can a great number of haJf-tones be secured with pleasing gradations and richness in the print. Scale of Contrast in the Negative.-Some plates and films are available which are capable of reproducing correctly all the various tones of the subject, even when the variations of light are more than 200 to 1. In the case where the lighting has a scale of only 50 to 1, the exposure of the negative might be increased four times over the least correct amount and still be a correct exposure, giving a true scale of the values in the lighting. In the latter case, the tones would of course be much denser and require 'longer printing time, but there would be the same proportion of contrast. As a rule, however, the negative had best be as thin as possible consistent with the maintenance of a complete scale of tones in harmony with the subject. Normal exposure of the negative is such that in development the deepest tone is just recorded by the time the highlight has reached correct printing opacity. That is, the negative should have a full range of tones with some detail in the deepest shadows, and as great a number of half-tones as possible, leading up to the highlights, which should all be distinguishable and not run together when printing. This resuU is attained by a long scale of lighting with all the possible intermediate tones, the giving of a rather full exposure,

CHOICE OF PRINTING PAPERS

and taking care not to overdevelop the negative. For example, if the light intensities of the subject range from 1 to 50, that is, with the highlights reflecting 50 times as much light as the darkest objects in deepest shadow, then the thinnest portion of the negative (the shadow) should transmit 50 times as much light as the most dense portion (the highlight). A long scale or contrast negative, then, is one where the thinnest portion will transmit perhaps 50 times as much light as the most opaque portion. A short scale or flat negative may let only 5 times as much light thru the shadows as thru the highlights. Scale of Contrast in Paper.-This discussion of the variation in the lighting and in the scale of opacities in the negative has been given in order to make more clear the range in tonal values of printing papers.1 The variation in exposure necessary to produce all the tones possib1e on a given paper indicates the sca]e of that paper. If a certain exposure gives a bare]y perceptible tint and 5 times that exposure gives the deepest black the paper is capable of recording, that is a very short scale or contrast paper. If on the other hand, 100 times as much exposure is needed, it is a long sc21le or soft paper. Obviously, papers can not record as long a scale of tones as plates. For there is a greater difference in the amount of light transmitted by the almost transparent part of the negative and the nearly opaque part, than there is in the amount of light reflected from the pure white and the darkest portions of a print. So from a pracical standpoint, only those gradations in the negative that can be reproduced by the printing medium employed, are of real value. Consequently, the 1

See Studio Light, May-Sept. 1917. Photo-Miniature No. 78: Printing Papers. Photog路raphic Researches of Hurter and Driffielcl,

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PHOTOGRAPHIC PRINTING

contrast in lighting of the subject should be sufficiently toned down and the negative so developed that its scale is no longer than can be adequately secured in the print. If the LS "' . negative has not , .. been made with this ideal in mind, the next best thing is to ,_, '-' use a paper of such \..t '-• contrast as will yield ... ... the best possible •• print from the nega'' '' ... tive at hand. '" Test Screen Negative. Papers from t~ different manufac·•., turers while often 13 labeled similarly may vary considerably in contrast. In order to determine beyond doubt as to which papers have the longest scale of gradation, e v e r y printer should make use of a test screen negative, sometimes called a "step negative". Such a nega(a)Soft (b )Medium (c)Contrast t" b Figure 9 Comparative Paper ConlVe may e pre. trasts (Shown by Test Screen pared from a piece • Negative). of 5x7 glass and very thin celluloid or even tissue paper. Cut a strip of celluloid one inch wide and seven •

•

CHOICE OF PRINTING PAPERS

inches long and attach to the glass with lantern slide varnish. Cut a similar strip !" shorter and fasten over the first, keeping them even at one end. Continue adding the strips, each !" shorter, until there are 28 strips on the glass, the last being but !" long. At that end there are 28 thicknesses of celluloid and at the other end only one. Number the strips with India ink. For convenience make from this plate, by contact, a positive on a plate or film. Again number the pieces along side the others and make another negative. This will show the two rows of numbers, one in white and the other in black. In testing papers, use this last negative, and expose so that with correct development at least two strips showing the dark numbers will be obliterated at one end. The negative should have a long enough scale that with the softest papers no tint will be visible at the light end. The comparative number of visible steps will indicate the contrast of the paper-the greater the number visible, the longer the scale of the 'paper. CHOICE OF CONTRAST.

In choosing the contrast of the paper to be used, there are several distinct cases to be considered. (See Experiment 8.) L!lng Scale Negative.-A negative with rather a contrasty lighting, (Figure 10), has been overdeveloped which results in excessive contrast with a scale perhaps as long as 100 to 1. Now if this is printed on a very long scale (soft) paper in which 100 times the exposure necessary to tint the paper is needed to give the deepest blacks, then the resulting print will be correct. (Figure 11.) For by the time the highlights are just tinted, the shadows of the negative will have

•

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.......

z :j z ~

Figure 10. Long Scale Negative:

Figure 11. On Long Scale Paper,

Figure 12. On Short Scale Paper.

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•

0:::

0 ........

t-d

~ • • ..-----..

z C) ~ •

t_%j ~

00.

Figure 13. Short Scale Negative:

Figure 14. On Short Scale Paper,

Figure 15. On Long Scale Paper. -:)

01 •

PHOTOGRAPHIC PRINTING

transmitted 100 times as much light, with the result that a rich black is reached in the deepest shadows of the print. Suppose, however, this long scale negative is printed on a short scale (contrast) paper where the deepest blacks may be obtained by only 20 times the exposure necessary for the first visible tint. By the time the highlights are tinted, the parts of the negative transmitting 20 times the light will give the deepest black the pape1路 can record, while all the shadow portions of the negative transmitting more than that will be wasted, since no deeper tint can be recorded on the paper. All the shadow portions are black and lacking in detail. Again, if this same short scale paper were printed only until the shadow portions were correct, the highlights would be greatly underexposed and very "chalky" in appearance. For while the densest portions of the negative transmit only 1Ao as much light as the shadows, the paper is unable to record below n of it. As a result, all those portions receiving less than n would be very much underexposed. If the paper is exposed between the limits given in the last two cases, the result will be that some of the shadows and some of the highlight tones will be "blocked", lacking in detail. (Figure 12.) Short Scale Negative.~Suppose a negative is at hand of such contrast that the shadow portions transmit only 10 times as much light as the highlights. This is consequently a flat negative with a short scale of tones in which no portions are either very dense or very clear. (Figure 13.) This negative naturally should be printed on a short scale or contrast paper. (Figure 14.) If a paper is selected of such range that only 路10 times as much exposure is needed to secure good blacks as for detail in

CHOICE OF PRINTING PAPERS

the highlights, the best print will be obtained. For . by the time sufficient light has passed thru the densest portion to give a visible tint in the highlights on the paper, the shadow portion of the negative wiLl have transmitted 10 times as much, which will give good blacks in the deepest shadow. Using a long scale or soft paper with a range of perhaps 100 to 1, for this negative, would give a very flat print. (Figure 15.) By the time the print has proper detail in the highlights, the shadow portion of the negative will have transmitted 10 times as much light. But this will only print the darkest portions of the print to a gray as this part requires 100 times the light to get good blacks. Thus the print will include tones only from a slight tint to a gray, and will be very weak and flat. In case this same paper were printed sufficiently to secure good blacks, the print would be gray and muddy in the highlights. For by the time the shadows of the negative are correctly exposed, the densest portion will have transmitted 11o that much light, whereas only 1Ao Jl necessary to bring out detail in the brightest highlights of the print. This portion is then greatJy overexposed. all intermediate parts being overexposed to a lesser extent. The print has good shadows but the highlights are gray and the print is very flat. If the paper is printed between these two limits, the middle tones will be of proper value, but the range of tones is so short that there are no good highlights or deep shadows. General Considerations.-1n general, a paper should have at least as great a numerical range of tones as the neg路ative, so that the print will have detail both in the highlights and in the darkest portions. If the scale of the paper is 路slightly greater, there is still bet-

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PHOTOGRAPHIC PRINTING

ter opportunity to secure detail thruout the print. In the ordinary studio where brilliant portrait negatives of good uniform quality are being made, the scale of the negatives will perhaps range from 1 to 40 up to 1 to 80 with a full range of half-tones. This being the case, portrait printing paper is usually made in only one contrast by each manufacturer. However, different surfaces may vary slightly while different makes often differ considerably in contrast. So if the negatives obtained are not of uniform contrast, compensation may be had by using various makes of paper, and variations in the developers, as will be explained later. The possibilities in the slower grades of portrait papers are not ful,ly appreciated. They usually give a longer range of tones and produce more harmonious results, especially from vigorous negatives. If the negatives are too variable in scale of contrast, resort must be made to the use of commercial papers. 路 Both amateur and commercial negatives are made under such widely varying conditions that no one contrast of paper would be suitable for this work. So manufacturers make this class of papers in from two to four degrees of contrast, some designating the different grades by numbers while others use letters. The longest scale papers are usually known as soft, the medium scale as norm,al, and the shortest scale as contrast or hard. A careful survey of the negative should be made before determining upon the degree of contrast needed to reproduce it.

CHAPTER VIII. PREPARATION AND .EXPOSURE. The ideal negat-ive, as stated before, is one with a long scale of gradation ranging thru a number of halftone's up to highlights that are not so dense as to block out the light entirely. A reasonably thin negative but with full detail, and a slightly olive or yellowish tone, is the type most generally preferred by printers. Improvement of Defective Negatives.-Unfortunately many negatives are defective in some way and need treatment before being printed. Those that are too thin and with a very short scale of contrast as a result of underdevelopment should be intensified. 1 In the case of a decidedly underexposed negative which is consÂŁquently too contrasty, a passable print may often be secured by making on film a very thin positive and then developing only until slight detail is obtained in the deepest parts. After being fixed, washed, and dried, this is bound in register with the original negative and the two are printed together. In this way the contrast is decreased, as wherever there was a clear portion of the negative, there will be a slight deposit on the positive, while the highlights will show no a~r preciable change as the positive is clear at those points. Reduction will help out in overdeveloped negatives or in those that are overexposed and underdeveloped. In the case of a very thin negative which could hardly stand reduction, the best procedure is to make a glass or film positive and from that a second negative on film. 1 See Wishka: Chemistry of Development, or any good book on negative-making for formulae for intensification and reduction of negatives.

PHOTOGRAPHIC PRINTING

This bound in register with the original negative will greatly increase the contrast in printing. Some of the deficiencies of the negative may be corrected by the careful use of the air brush. It is especially useful in building up the highlights on the back of a flat portrait negative, making the features stand out, and giving roundness and atmosphere. It is also conven~ent in holding back the shadows and in working 路in backgrounds. In the case of a negative which lacks brilliance and sparkle, if the back is flowed with ground glass substitute and work is done with a soft lead pencil (6 B), a great improvement may be noticed. The little highlights on the dress and accessories may be deepened, flat features built up, and shadows on the neck filled in, so that when reproduced, the print has the sparkle of a more perfect lighting. If the negative is a film, the same results may be obtained by attaching it to a piece of plain glass and flowing that. In either case, the thickness of the glass so diffuses the pencil work that great accuracy is not necessary. Crayon sauce, applied by the aid of paper stumps (tortillons) or cotton on a tooth pick, may be used instead of the pencil, if desired. Plastocine or modeling clay may be mixed with a small amount of dry color of a yellow shade and dabbed on the back of the glass negative at points that are too thin. Enough of this yellowish mixture will adhere to hold back the light to a considerable extent and so prevent those portions from printing too deeply. Blue or yellow water color is sometimes used for the same purpose. Another convenient method for holding back certain portions of the negative that print too rapidly is to build up the front of the printing frame to the depth of one to two inches and cover with cepa or onion skin paper. If opaque is dabbed lightly over the thin por-

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PREPARATION AND EXPOSURE

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tions it will not show in the print and yet will be effec.. tive in holding back the light in those portions .. 2 Backgrounds. Since studios seldom have a sufficient variety of backgrounds to be appropriate for each lighting and to properly balance the composition in every picture, photograph's are often taken against a plain black ground and then a background of some sort "worked in." This may be done with a soft pencil or . crayon sauce on the back of the plate which has~ been coated with ground glass substitute, or . if preferred it may be worked in on ground celluloid. Ready-made grounds on celluloid are on the market and are very convenient, but are, seldom exactly suited to the subject. If used, one or two pieces of plain glass should be interposed between the background and the negative. This will cause the background to print slightly out of focus and thus de·tract less from the figure give the apand better . pearance of distance. '

courte~y of Ea1tman'Kodak Co . Figure l6. Professional Printing Machine.

Printing Machine.The printing machine used should accommodate . llx14 paper as tinted borders and plate-sunk centers are often made to this size. Figure 16 shows the type of machine which is perhaps in most general use. As mentioned in ChapBy

Photo-Miniature No. 126: Putting Backgrounds into Por-

trait Negatives. I •

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PHOTOGRAPifiC PRINTING

terlii, home-made machines are very satisfactory if carefully made. Most machines on the market have from 4 to 6 mazda lights of 75 to 150 watts in size and . a 10-watt ruby light. In one type of machine, il• lustrated in Figure 17, special provision is made for dodging. Not only does the hinged top open in the regular way, but a second hinge allows the plate glass, negative, paper and hinged top all to be raised as a unit, thus allowing an auxiliary light to be used thru the glass to give added exposure where necessary. . C·a re must be taken to keep the printing surface on top of the machine clean or an undue amount of spotting of By courtesy of the Pa-k o Corporution. the prints will be neces·· · Figure 17. sary. Profegsional P1·inting Machine. A good timer or clock, reading in seconds, is almost indispensable for producing good p~rints. If the current is not constant it .is best to use a timer that is so operated by a motor that its speed will vary with the fluctuations of the current so that it automatically giv~es to each print the exposu-r e for which it is set.

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Cot·rect Exposure. In order to intelligently determine the proper amount of exposure to give a print, it is necessary to understand what constitutes correct exposure. While modification must be made to secure

PREPARATION AND EXPOSURE

any special effects in regard to color, contrast, and other factors, in general a print is correctly exposed if, after the sensitive silver salts which are affected b11 the light have all been changed to metaUic silver by the developer, there is a proper range of torwl val.ues in the picture. To understand this range in values, imagine a line divided into 100 parts, one end representing pure white and the other a deep black.

A w

oo oo w

oo B

In most prints the correct range will lie between 20 and 80 having no absolutely white paper and none 路dead black. The majority of prints, however, are likely to be rendered either too dark or too light, usually the former, giving shadows in which most of the detail is obliterated. The photographer, like the musician, may transpose the entire 路tonal composition to a higher or lower key, thru his control of exposure, but he must retain the same relationship in each part of the scale of the various gradations of highlight and shadow. A print, then, is properly expose~ if on full development it is neither too light nor too dark. Exposure and development are so interrelated that one cannot well be considered without the other. 3 The theory covering what constitutes correct exposure and development should be more widely studied than it is. Many rely on the lazy way of giving too full exposure and then trusting to short development for the desired result. This is perhaps the most common trouble with beginners. This overexposure results in the various gradations being correctly registered and then being destroyed as exposure proceeds beyond this point. Development is then too rapid; the highlights are flat3 It is suggested that a study be made of development as given in Chapter XI, in connection with this discussion on exposure.

PHOTOGRAPHIC PRINTING

tened and show too much detail; the shadows lose detail and become smudgy, and the whole print takes on a general muddy appearance. If toned, it will have a sickly yellow color. (See Experiment 15.) Underexposure, on the other hand, may record only the gradations from the thin parts of the negative, resulting in a cold weak b'lack and white print which if forced may fog in the highlights causing flatness, while in s路epia it will be a cold disagreeable purple. In the case of a thin flat negative, the question often arises as to whether it is better to give a short exposure to a strong light or a longer exposure to a weaker one. General opinion seems to favor the latter. A certain minimum quantity of light seems to be necessary to affect the silver grains, so using a weak light may cause a smaller proportionate number to be affected in the highlights, resulting in more contrast or brilliancy. Exposure of Bromide and Chloride Papers.-With silver bromide papers as in the case of dry plates, a certain amount of added contrast can be secured by shortening the exposure and giving rather full development. Silver chloride papers, however, which are largely used for contact printing, must have reasonably correct exposure and development if passable results are to be secured. Rather full exposure seems to assist in getting the most brilliant results for black and white prints. but gives slightly less for those to be toned. Some papem being a combination of these types have considerable flexibility in regard to exposure and development. DETERMINATION OF THE LENGTH OF EXPOSURE.

Exposure Test Rack.-A system of comparing negatives with those of known exposure on the kind of paper in use will save much time and paper in se-

PREPARATION AND EXPOSURE

curing correct results. A rack may be built to hold from five to seven pieces of ground glass. (See Figure 18.) Over the first, third, fifth, and seventh are fastened negatives of known exposures of five, ten, twenty, and sixty seconds, or whatever amount applies to the most general run of the negatives used. ..............

......... ·~···-,.__-

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. , •• uc S't••lf·•

•ut••••.r Ullol £•f

, .. ,.....,

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Figure 18-Exposure Test Rack.

By holding the negatives to be printed between the negatives of known exposure, it is easy to detenninc the comparative density and the probable exposure necessary. Allowance must be made if negatives are not uniform in color, as a more olive or yellow color increases the time of exposure. This negative test rack may be in the form of a box with small white or yellow lights which may be switched on at will. This may then be placed convenient to the printing machine. Test St?·ips.-This is the method most commonly used in determining the proper exposure. A sheet of printing paper is cut into several smaller pieces. One of these is placed on the emulsion side of the negative in the printing frame or on the printing machine, and the light turned on for the estimated time necessary. The strip is then placed in a developer made up according to the formula for that particular paper and developed for the length of time indicated by the manufacturer as being correct. For most portrait papers this is from one and one-half to two minutes, and for most amateur and commercial papers in their special developers from twenty to forty seconds. Observation must be made both of the length of exposure and of

PHOTOGRAPHIC PRINTING

the time before development seems complete. The test strip must be left in the developer, however, for the time recommended, regardless of effect. Now if the strip is too dark, it indicates overexposure and that the next test should be exposed fo1路 a shorter time, while if too light, that a longer exposure is needed. As soon as a test is secured which is of the desired depth, all the prints from that negative should be given that same exposure and developed until they reach the depth of the correct test strip. Developing by time may not give identical results as the strength and consequently the speed of the developer may not remain constant. As the printer acquires more practice in judging when prints are fully developed, he will find it better to develop his test strips by inspection rather than to a definite time. The factors affecting exposure may be summarized as follows: 1. Density of negative 2. Colo.r of negative 3. Strength of printing light 4. Speed of paper 5. Effect desired: i.e., black and white or sepia, light or dark, etc.

Dodging.-Many negatives are too contrasty because of poor lighting or other conditions, parts of a view or one side of a face in a portrait often printing too dark. This can be remedied quite materially by tearing out onion-skin, cepa, or other tissue paper in such a shape as to cover the part that prints too dark. This is then placed on the ground glass an inch or two below the printing surface directly under the portion it is desired to hold back. The ground glass or other support for the tissue should be raised as far as possible without the print ,showing any abrupt change where the edges of the tissue come.

PREPARATION AND EXPOSURE

8.7

Sometimes one end of a group negative will be quite dense and then shade off to a decided thinness at the other end. If two or three sheets of tissue are placed und:r the thin end of the negative and then torn off so that the edges are a short distance apart, there will be a gradual blending as the negative becomes thinner, and a good print will be secured. Diffusion Printing.-(See Experiment 20.) Diffusion is often desirable either to soften the effect or to portray the feeling intended in a particular print. Altho this is perhaps most satisfactorily obtained by the use of sp:::cially made lenses, yet a softening or diffusion may be produced in printing that is very similar. One method is merely to hold the paper down on a portrait negative with two fingers, one over each eye of the figure. With the other hand, tap the paper lightly during exposure. Perhaps the best way is to make part of the exposure with the printing paper in contact with the negative and the remainder with one or two pieces of plain glass interposed between the paper and the negative. Co1路rect registration may be easily obtained if a printing frame is used and care is taken that the negative and paper are slid down in one corner as far as possible. Expose from 70 to 80% of the time required, remove the printing paper, and place the plain glass on top of the negative. After replacing the paper and being sure that the negative, glass, and paper are all registered in the original corner, replace the back and give the remainder of the exposure. The degree of diffusion can be made to suit the picture, by variation in the relative length of exposure, in and out of contact. Figure 46 (Chapter XVII) shows a print made with two pieces of glass interposed for 40% of the exposure. Other methods as printing thru ground celluloid,

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PHOTOGRAPIDC PRINTING

silk bolting cloth, or screens of various kinds are seldom as effective or satisfactory. ~ USE OF TINTED BORDERS.

I I

Many pictw~es, especially portraits, are rendered more beautiful and harmonious by printing on a larger sheet of paper with a slight tint around the picture. (Figure 19.) Oftentirttes, also, the change fl'Om the tone of the pictm~e to that of the folder enclosing it is too abrupt and may be modified in this way. The tendency of many workers when using borders is to make them too elaborate and too dru."k. A 4x6 picture pl~inted on 7xll paper with a margin of l t " at the sides and 1!-" or 2" at the top would look Figur e 19-Showing Tinted Border. well with the paper tinted lightly for perhaps ! " around the picture. An almost imperceptible tint on the rest of the paper would be an advantage in case there is too great contrast between the white paper and the mount. â&#x20AC;˘

PREPARATION AND EXPOSURE

Tinting Masks. Several varieties of ready-made masks are available, some being so constructed that about thirty kinds of borders may be printed. When making home-made masks, great care must be exercised that the different parts register properly. Mask charts may be purchased with guide lines laid off in squares and are a great ~convenience. Masks are often made by using film photographic copies of canvas, burlap, wall-paper. etc., which are printed in the u~sual manner. I

â&#x20AC;˘

Figure 20

Tinting Mask.

Tinting masks (Figure 20) usually consist of three or more parts: (1) A heavy opaque paper (b) with a square or oval opening located so as to give a similar margin at the sides and top. Along the top and sides of the upper left-hand corner of this negative mask are fastened strips of _cardboard . which form the registering angle. (2) A ground glass or film, called the tinter (a), sometimes with a line or other border etched in the ground glass, and with a registering angle agreeing with the one on the negative mask. The portion of this second mask corresponding to the opening in the negative mask, but n" smaller, is blocked out.

â&#x20AC;˘

PHOTOGRAPIDC PRINTING

(3) Supplementary forms as (c) and (d), for making the various tints and designs. How to Print Borders.-In printing tinted borders, any negatives excepting those with white backgrounds may be used. The procedure is as follows: (1) Place negative on. glass of machine or printing frame and cover with the negative mask. (2) Register the paper in the upper left corner in the l'egistering angle, and expose. (3) Remove negative and negative mask. (4) Place tinter on machine and cover with one of the supplementary masks if desired. (5) Register printing paper (same sheet as before), and expose so that when developed the tint will be about equal to the middle tones of the picture, or a little lighter. Ordinarily if the negative requires a 10-second exposure, the border will vary from ito 1 second. (6) If desired, remove the supplementary mask and replace with another. After putting the paper in position again, expose so as to get a shade lighter tint. As a rule, tints furthest from the picture are printed the lightest. CHEMISTRY OF LIGHT ACTION.

Mention has already been made of the fact that in exposure the light has some kind of an effect upon the sensitive silver salts of the paper, that makes possible their reduction to metallic silver by the developer. The emulsion contains very minute crystalline grains of silver salts, as silver chloride, silver bromide, etc., some of which are extremely small and others much larger by comparison. Microscopic examination indicates that all of these are not equaliy sensitive to light action. In general, the emulsions containing the coarser grains are the faster, but all grains of the same size

PREPARATION AND EXPOSURE

do not appear to have the same sensitiveness. When exposed under the negative, a greater amount of light penetrates the thinnest portion to the paper and the action may be sufficient to make all the grains capable of development. Only a small amount of light gets thru the denser portions of the negative and this only affects a small number of the grains (probably the more sensitive ones) to a degree which renders them capable of being reduced by the developer. Latent Image Theories.-Just what the action of the light is upon the silver salts of the paper is a question that has long been a subject of controversy and that has not yet been definitely determined. Many hypotheses have been advanced to explain the nature of the latent image. The most common are: (a) Molecula1路 Strain Hypothe8i8.-Many arguments have been advanced to prove that the action 1>f light is physical rather than chemical. It is entirely reasona~ble to suppose that before the light action becomes great enoug.h to cause any change in the composition of the molecule of the silver salts, it may be great enough to cause s1>me sort of a strain. This internal strain set up in the molecule of silver chloride may be such as to cause some re-an路angement of the atoms or cause some mechanical strain under which the molecule can more easily be (broken up by the developer with the deposition of metallic silver. The grains are then reduced by the developer in proportion to the molecular strain. (,b) Sub-haloid Hypothe8i8.-This theory has tbeen one of the most generally accepted among scientists. It harmonizes with the observed fact that light liberates chlorine fmm silver chloride. It is assumed that this takes place in the silver partiele and leaves a molecule containing less chlorine than the normal AgCl,-pos3ibly Ag2 Cl. However, no such reduction product has been detected and it is extremely doubtful if such is formed. Moreover, silver and chlorine are both monovalent. This theory would, however, explain nicely why the develo11er attacks the exposed portion in preference to the unexposed, for here the silver chloride has heen changed to a sub-chloride by the light and hence is already partly reduced.

PHOTOGRAPHIC PRINTING

If this theory is correct, the chlorine or ·bromine liberated by the light action likely interacts immediately with the gelatine and is thus removed from any further chemical action, thus causing no restraining power on the later decomposition of the molecule. This would perhaps account for the extreme rapidity of prese.nt day plates and films. (c) Silver l'article HypotheBiB.-This theory in brief is that light action removes the chlorine or other halogen from a few of the molecules with the formation of some extremely minute particles of metallic silver. 'Dhese act as centers upon which the developer deposits silver from the silver chloride grains near by. Chemical evidence, however, points toward there being no free silver liberated, especially by the extremely short e~posures which can be given to rapid dry plates. (d) Oxy-chloride HypotheBiB.-ln the opinion of some, the latent image con!lists of oxy-chloride, oxy-bromide or whatever haloid salt is used. According to this view, the silver 11alt in the presence of light loses a portion of its halogen and 111bsorb11 oxygen to· produce a compound that is more readily acted on by the developer. This theory is not in line with the observation that silver chloride may darken and liberate chlorine in the absence of oxygen. (c) louizntion Hypothesis.-Much of the later research on thi>~ question is in the direction of this theory. The atom may not consist of the solid particle of an element, but .may be the complex stt·ucture of a positively-charged nucleus with perhaps many negative electrons revolving a1·ound it. The light waves w.hich may be puls(':s of energy in the ether, may on striking the sih·er grains cause the escape of the negative electrons, due to some electric force. With the removal of the negativelycharged t>lectron;;, the remainder of the molecules acquire an t>ntit't'ly new ;;t"t of characteristics, making them more easily atft>ctro b:,· tht" de,·eloper.

CHAPTER IX. VIGNETTING

Before proceeding to the development of the print, it may be well to consider other printing methods. Of these the process known as vignetting is quite often used. Vignettes are pictures in which the margins or other selected portions gradually fade away. Most often the blending is done on a white background, tho occasionally a dark one is used. While they are often made by using a vignetting device in front of the camera, this method is most unsatisfactory for several reasons: (a) the shape is almost never suited to the subject, (b) the vignetter and background are seldom lighted so lhat they blend properly, (c) white grounds are not often represented as such. Suitabllity.-Vignetting is especially suited to pictures where light dainty effects are desired. For women's and children's pictures, few styles are prettier than vignettes on white grounds, worked up with pencil, crayon, or air brush. For the best results, the subject should be dressed in light clothes while the chairs, playthings, or other accessories should also be light in color as these best blend into the white ground. While they may be pleasing in some cases, vignetted photographs of men are usually not so effective since this type of picture does not accent the sturdy and active qualities. Pol'traits in this style should be rendered in a fairly high key, having no portions of the print as dark as in other kinds of work for therein lies their daintiness and charm.

PHOTOGRAPHIC PRINTING

Ideal Negative for Vignetting.-The ideal negative is one which has sufficient density in the background portion to prevent enough light from reaching the paper 'to tint it by the time the figure is of proper depth. In other words, when the figure is sufficiently printed, the rest of the print should be pure white. This result is usually attained by the use of a white or blue-white background which is lighted as much as possible without causing halation. The plate is then developed for the maximum density in the background consistmt with good gradations in the subject. Preparation of the Negative.-If the negative has too short a scale of gradation and is consequently flat, the background will transmit light enough to give a deposit before the figure has reached sufficient depth. In this case some method must be utilized to increase the opadty of the negative background, or considerable difficulty will be encountered when vignetting, to secure pure whites. The air brush is one of the best aids for this purp:>se. If a film negative is being used, it should first be fastened to a piece of plain glass. The back of the plate or glass is now thoroly cleaned as the air brush color will not stick to the grease of finger prints. 1 Sufficient lamp black or water-proof color is then blown over the background on the back of the negative so that it will not print thru. Where the color has extended over the figure, it may be easily removed by dampening it with â&#x20AC;˘the breath and immediately rubbing with cotton on a tooth pick or paper stump. The erasing should be so done that the edge is not sharp but soft and diffused. A simpler method is to paint opaque on the background up to the edge of the figure on the back of the 1 Glass may be cleaned with a solution of oxgall or of alcohol, or with a dilute ammonia solution.

VIGNETTING

plate, but this ~s open to the objection that the edge of the figure in the print is likely to be harsh, giving the effect of a cut-out picture. Perhaps a better meth路路 od is b flow the glass side with ground glass substitute and rub on enough crayon sauce to make the background opaque. Of course the edges must be softened to secure good results. If a negative with a black back路ground must be vignc1~ted, first retouch the negative with a 6B pencil for about an eighth of an inch around the picture, ;:,sing very light touches next to the figure and then . increasing the density as much as possible further from it. The rest of the background is then blocked out with opaque on the back of the negative, the pencil work serving to soften the edge up next to the figure. If the figure is very -close to the margin of the negative it may be necessary to paint the edge of the glass plate wilth opaque to prevent the strong light from coming thru. METHODS.

There is perhaps a greater variation in the methods of vignetting than in any other printing process, each printer having his own ideas as to what way is most convenient. Since the principles of vignetting are the same, regardless of method, a description of several of the better ways should give an adequate understanding of the process. In the examples of vignettes usually sem, the poor far outnumber the good. There is a tendency to have a harsh abrupt outline, or at the other extreme, to have a dark halo around the picture. Mechanical Deviees.-Several ready-made vignetting frames are available but are not to be recommended as in general they are not capable of doing first

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PHOTOGRAPHIC PRINTING

class work. With such vignetters it is difficult if not impossible to have the figure blend off properly to a white ground without a dark shadow around the head. There is also not sufficient adaptability to secure enough variation of shapes to fit all subjects. •

Printing Frame Method. This method is capable of turning out as good work as any but is generally used only when a regular printing· machine is not available. The materials necessary are printing frame, strips for vignetting frame, a large cardboar.d.' tissue paper, pen c i I, opaque, o p a q u e b r u s h, binding strips, and glue. On the front of an llx14 printing frame is fastened a wooden f r a m e (Figure 21B), with the D opening of such · size that an llx14 Figure 21. . glass will just drop Vignetting: Printing Frame Methe1d. into it. The vignettingstrips making up this frame should be 1" thick at one en.d and ! " at the other. At the thick end there is an opening into which a cardboard slides in a groove in the frame. rrhis is shown pushed up nearly to the top. Two thirds the distance from the thicker end •

VIGNETTING

of the frame, an opening is cut in the cardboard the size of the negative. over which is pasted a piece of cepa or other water-proof tissue paper. Procedure. Remove the back (D) from the printing frame a11d fasten the corners of the negative (shown in C) to the glass , over the opening in the cardboard so that the base of the picture is toward the thicker part of the frame. This is to give a better opportunity for blending or fading out the lower part of the picture. Now remove the glass with the negative from the frame and place it in the opening in the vignetting frame in front, so that the emulsion of the negative is touching the tissue paper. Hold the frame up to the light and with a soft pencil trace the shape desired O!l the tissue (shown in A). The pencil work should closely follow the outline of the figure except at the neck, L:-===-;;;...;;;..·- - - - - - - - J where more space will provide for a slight shadow when Figure 22. finished and make for easier Correct Form of Vignette. air brushiitg. The lower portion of the vignette should be marked out following the contour of the neck opening of the clothes \vorn. If the portrait is of a girl in evening dress, the vignette should be rounded in the same general way; if the neck opening is Vshaped, the vignette should be simNar. (Figure 22.) No matter how the sitter is turned, the lowest pontion of the vignette must be at the center of the front of the person, bElow the lowest point of 1the neck opening and not necessarily. at the center of the figure. This . •

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PHOTOGRAPHIC PRINTING

lack ·of correct 1ine is one of the most common and disagreeable effeets found in many pictures of this style. (Figure 23.) After the outline is traced on the t issue, the glass and negative are removed, the frarne held up ·to the light, and the tissue opaqued on. the front side around the opening (Figure 21B). T·h is. blockin~g should follow the pencil outline but be saw-toothed. Now turn the frame, front down, and place absorbent cotton around the bottom of the figure following the pencil marks (21A). The cotton should be pulled apart, giving a soft fluffy edge so as to get the best ·blending power. In case the negative is thin and tends to print thru the background. it may be necessary to place cotton entirely ·a round the figure opening. Place the glass with negative back in the. printing frame and cover Figure 23. with an llx14 mask of nonIncorrect Form .of actinic paper (21C), with an Vignette. opening over the negative cut a qu·a rter of an inch smaller to prevent any diffused light from striking the sensitive paper. The vignette is now ready for printing. 'T his preparation may seem somewhat lengthy but it can easily be done in a very few minutes. When making another vignette, the tissue paper is replaced by a fresh piece, marked and blocked, the cotton arranged to suit the new negative, the mask again placed in position, ai1d the preparation is complete. _.;_

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Post-Office Paper Method. ·T his is one of the

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VIGNETIING

methods most commonly used in studios. The work is done on a regular printing machine and if carried out properly, the results are equal to those obtained by the printing frame method. The materials necessary are: large cardboard, large sheet of black paper, cotton, pencil, knife, and post-office paper. This last is an orange or yellow non-actinic paper commonly known by the name given. ProcedU?·e.-Place the negative on the plate glass of the printing machine and cover with a piece of postoffice papzr somewhat larger than the negative. If the lights are turned on, the image will be plainly visible and the outline for the vignette can be marked on the paper as in the method just described. Now cut out the opening following the pencil mark but making the outline saw-toothed so as to soften the edge of the image. Place this paper on the ground glass of the machine and over it lay a cardboard the size of the light box with an opening in it the size of the plate. Around the lower part of the vignette opening place cotton, taking care that the edges are nicely frayed out. If in bunches, it will cause the outline of the vignette to be irregular. (Figure 23.) In case the negative is thin, place the cotton entirely around the opening. Now put 'the negative on the plate glass over the cut-out form so that the outlines coincide. Cover the negative with a pi€ce of thin black paper the size of the machine top, having an opening just slightly smaller than the negative. This is to prevent stray light from striking other portions of the printing paper and causing fog. Next adjust the distance between the ground glass and the printing surface. If the ground glass with the vignetting materials is too close, parts of the image may be cut off or have a sharp edge, while if too low, a dark halo or fog may result. In case the ground glass is not adjustable for height, the vignette may be made up on a piece of plain glass and then

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100

PHOTOGRAPHIC PRINTING

raised by being placed on two sticks, resting on the ground glass. It is well to have the upper portion slightly higher than the ·b ase of the picture, so as to get a more ·g radual fading off, of the lower portion. •

Sand Method. This is somewhat simpler than the method just described but is more "mussy". 'It is quite commonly used in studio work and anyone with a

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Figure 24

Vignetting: Sand Method.

little practise should be able to secure good results. The materials needed are: · an 8x10 plain glass, small soft brush, and clean fine sand, sign painters' sand. cornmeal 7 or other similar substance. · •

~ t# (. •

- ......

•

.. .II •

•

VIGNEtTING

101

Procedu1路e.-Construct a tray by fastening narrow strips of cardboard to all four sides of the 8x10 glass. These sides serve merely to keep the sand from getting on the machine and need not necessarily be used. Lay this glass over the negative, and on to the glass siiit or pour the vignetting material. (The black sand used by sign painters is one of the best materials, but if the others mentioned are fine, they will be satisfactory.) With the small brush make an opening in the sand, of the shape desired for the vignette. (Figure 24.) This is easily done as the image of the negative is plainly visible when 'the printing lights are turned on. Be sure that the sand is thin at the edges of the vignette so that the light in passing thru will blend nicely. The sand should be of sufficient depth that not enough light will penetrate to the paper emulsion to cause fog. Now place the glass containing the sand vignette on the ground glass underneath the negative so that the opening coincides with the outline of the figure. Then raise the glass until the sand touches or very nearly touches the underside of the plate glass. Cover the printing surface of the machine with black or other opaque paper, having an opening slightly smaller than the negative, and proceed to print. In the illustration the printing glass is raised to make visible the construction of the vignette. Air Brush Method.-Those who are experienced in the use of the air brush will find in that instrument a partial solution for the removal of the fuss and bother of making good vignettes. After the background is air brushed on the back of the negative to secure opacity, the plate is turned over and the lower part of the figure air brushed on the front, care being taken that the figure blends off softly and evenly and that the shape is correct. A very fine

102

PHOTOGRAPHIC PRINTING

grade of lamp black or non-actinic color, which will Âˇnot show specks where the image fades off into the white paper, should be used. After this work is finished, the negative needs only to be covered with a piece of opaque paper with the opening cut out as before, and is ready for printing. Cyanide-Iodide Method.-In Chapter XVIII on Commercial Printing a formula is given for a reducer suitable for use on prints. Instructions given there must be carefully followed in using it as it extremely poisonous. If a dark background print or one with the figure extending to the bottom of the print is to be made into a vignette with a white ground, this reducer may be used to remove the silver deposit around the image and to blend it off in the shape desired. Vignettes made by other. methods may also be corrected or improved by the use of this reducer, especially those 1that have a dark halo around the figure, sharp irregular edges, or show fog in the background. Combination Vignettes.-For a number of poses of a child or for a family group made up of separate poses of each member, no type of picture is so pleasing as a combination vignetted on a single large sheet of paper. (Figure 25.) To secure good results without an excessive amount of work, it is imperative :that the negatives be made with white backgrounds. Only those who have tried to make light dainty vignettes from negatives with dark grounds can appreciate the difficulties. While two pictures may often be so spaced as to give an agreeable composition, yet as a rule any odd number as three or five are more easily arranged to give good balance. Small combinations may be made up with two or three negatives vignetted in the manner ex-

â&#x20AC;˘

•

103 plained .under the post-()ffice paper and sand methotls. If the negatives are of the same printing speed, they may all be printed at once. If not, then the exposure time on each must be oetermined and the negatives p-rinted separately in their proper position on the paper, the .o thers in turn being covered with opaque paper. More satisfacto,r y than this is the use of a frame 12 inches by 4 feet, such as is used for printing cireuit or long panaromic pictures, as this permits of almost any desired size being made and affords better opportunity for working up the vignettes in proper shape. Fo,r convenience and the best results, the negatives should be air brushed on the back around the upper

•

Figure 25

,C ombination Vignette.

This is an example of a combination priprt made from dark ground negatives, air brushed, and printed one at a time on a printing machine.

part of the figure to block out any undesirable portions of the background. Then by breathing on the plate, the color will be moistened sufficiently that where it overlaps the image, it may be easily rubbed off, if this is done immediately. This should be done in such a way that the edge is slightly diffused. . On the emulsion side the base of the picture is blocked out with the air brush, care being taken to have a gradual even blend..

104

PliOTOGRAPHIC PRINTING

ing of the image. If films are used they may all be attached to the glass of the printing frame and the work done on the back. A large piece of opaque paper is now placed over the negatives with openings cut out to show all of each negative except the edges. If the negatives are not of the same density, they may be printed one at a time over a printing machine or in front of an electric light or other light source, covering up the others. Or one or more sheets of tissue paper may be placed across the front of the frame protecting those negatives which print too rapidly, so that all print in the same time. Exposure may now be made of the entire vignette by artificial light or by diffused daylight. In case an air brush is not available, the printing frame may be covered 路with tissue paper which is opaqued around the figures. Cotton may then be used between the tissue and negatives to give proper diffusion where the image fades out and路 to prevent the light from printing any undesirable portions of the background.

CHAPTER X. COMBINATION PRINTING. While not one of the easiest of photographic processes, yet combination printing is at times most necessary and if carefully carried out, the results amply justify the time and labor involved. There are many opportunities for failure, but by careful attention to details, even the novice will soon be able to secure more than passable pictures. However, such little things as wrong perspective, the lighting on clouds from a direction different from that of the landscape, or a harsh outline where views are joined, will easily mar the final results. There are a number of conditions under which combination printing may become advisable. A landscape may be lacking only suitable clouds to give perfect balance and pictorial quality. View negatives may need to be joined to form a panoramic picture. Or at times, in order to include all of a tall building or sufficient of an interior, the prints from two or more negatives have to be combined. Of two negatives of the same group one or more persons may have moved in the first, and other portions of the second may be scratched or spoiled. There is a great variation in the methods used by different workers, but only two will be described as these are less complicated than many others and should produce results equal to any. Copying Method.-This method while quite simple must be followed in a painstaking manner if good results are to be obtained. Suppose two negatives, No. 1 -and No. 2, have been made of a group. In No. 1, the head

106

PHOTOGRAPHIC PRINTING

of one figure is blurred or the eyes closed, while in No. 2 this figure is all right but several others are out of focus. Make prints of equal density from both negatives. Cut out the good head or other POrtion from the second print, and carefully sandpaper the under portion of the edges of the cut-out part to a very fine edge. If any white shows along the edge, darken with a spotting pencil. Now soak up the first print and the cut-out image and float the latter on the former. · Cover with a piece of glass and carefully squeegee in contact. The combined print is now copied and with a reasonable amount of work with the retouching brush and pencil on the neg.ative, ·no sign of the joint should be noticeable. Masking Method.-While somewhat more compli- . cated, this method should find wider application than the one just described, since it has the advantage of gi:ving prints with none of the grain so often seen in copies. If the blmding or joining is properly carried out, the result will be even more perfect. Those who under.:; tand and can make tinted borders as described in Chapter VIII should have no trouble as the principle of the method is the same. The same illustration will be used, of substituting a figure from one negative for the same one in another, or sel€cting the best figures from two similar groups. Figure 26 shows the prints made from two such negatives. No. 1 has rather poor pictures of the two smaller children while No.2 has a bad scratch on the face of the larger girl. In order to secure a satisfactory print, the upp2r portion of the girl in the center may be printed from Negative No. 1 and the remainder of the picture from Negative No. 2. Procedur.e.-If films are being used, registration will be made much easier if they are trimmed so that the left sides and upper ends coincide when the images ~xactly correspond. Place the negative which contains

•

'COM.BINATION PRINTING

1:07 •

the lRJrger number of figures suitable f~r use, No. 2 iu this case: on a printing machine, or in a printing frame whi~ch is then held up to the light. A piece of postoffice or other semi-transparent non-actinic paper is placed over the negative so that the upper left corner exactly coincides witl1 the corner of the negative. With a pencil carefully trace the outline of the figure or oth,e r portion that is to be replaced. This will be plainly •

No. 1 No. 2 Figure 26 Prints frotm Defective Negatives. •

visible thru the paper. Blending will usually be easier if the substitution is mad,e along the outline of the image or the deep::r shadows. For the best results, t he line should run thru portions of the negatives that E'xactly coincide. This can be determined by superimposing the negatives and examining before a strong light. In the example given here, the line of substitution is shown in Figure 28. . Next re,move the orange paper and with a stencil '•

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108

PHO'rOGRAPHIC PRINTING

or other sharp knife cut along the outline as traced. Save both portions of this paper as they will be used as masks. Glue these two portions of paper to two separate pieces of glass in such a position that when the upper left one registers with the corresponding corner of the glass, the cut out edges of the two will coincide, both glasses being of course in register. (Figure 27.) In a case such as this where Mas.k (a)

•

(a)

Figure 27

(b)

Combination Printing Masks.

does not reach the registering angle of the glass, first lay both masks in position on one glass so that the cut edges coincide, with (~b) properly registered in the corner. Fasten down Mask (a), then remove (b) and fasten to the second glass as described. Place Mask (a) in the printing frame and over it place two pieces of plain glass and then the negative from w·h ich Print No. 1 was made. The glass helps to give a softer blending line where the two portions of •

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COMBINATION PRINTING

109

the picture join. The mask in this case blocks out the two smaller girls whose pictures are not satisfactory and permits the larger girl to be printed. The resulting print if developed at this stage would appear as in Figure 28A. Now in place of Mask (a) su.b stitute Mask (b) and use the negative from which Print No. 2 was made instead of No. 1. If another piece of paper is exposed, •

•

• •

Figure 28 ·P rints from Masked Negatives.

the result will show the other portion of the picture (Figure 28B). In practice these two separate prints are not made, being given here only for the purpose of illustration. Instead, use the same sheet of paper for both printings, having the proper corner registered in each case, and the final result should be a perfect picture, showing no indication of where the two portions are joined. (Figure 29.)

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110

PHOTOGRAPHIC PRINTING

In order to be more sure that the images will join properly, it is well 'vhen ready to make the first exposure, to trace lightly . on the back of the printing~ paper, the outline of the portion to be replaced. When mabing the se·cond exposure, see that the edge of this mask coincides with the one traced.

•

Figure 29

Finished Combination Picture.

This method is especially good when printing in clouds from one negative on to the landscape from another, ·a nd when joining views from two negatives taken from the same point so that they overlap. If necessary, portions from three or more negatives can be printed together by the aid of suitable masks . •

CHAPTER XI. DEVELOPMENT. Function of Developers.-The light action on development printing papers is so slight that no image can be sem. Therefore some chemicals must be applied to the paper which will render visible the latent image. Such compounds are termed developers. The function of these, then, is to reduce the light affected silver salts to metallic silver. A d::finite amount of energy is necessary to b1ing about this change. If part of this work is accomplished by the light action, there will be less for the developer to do. Consequently, those particles of silver salts that have been partly reduced by the light will require less energy for the developer to complete the action. This makes it possible for a properly adjusted developer to act only on the light affected portions. Chemistry of Development.-Space will not permit of a thoro technical discussion of this question since there are a number of theories in regard to the action of the developer. 1 The developing reagents used may directly reduce the silver salts but as they are ready absorbents of oxygen, it is more likely that action takes place in one of the following ways: (1) The reagents may be oxidized by the oxygen of the water, leaving the hydrogen thus set free to combine with the bromine lFor more exhaustive information, see: Flint: Chemistry for Photographers, pp. 61-78. Derr: Photography for Students of Physics and Chemistry, pp. 123-128. Roebuck: The Science and Practise of Photography, PPâ&#x20AC;˘ 55-1>6.

112

PHOTOGRAPHIC PRINTING

or chlorine of the silver salts with the formation of hydrobromic or hydrochloric acid. If this were to remain free, it would retard development. So sodium carbonate or other· alkali is added which combines with this acid, forming a weaker one. (2) Or according to another theory, the sodium carbonate reacts with the silver salts to form a chlmide (or bromide) and sodium bicarbonate, depositing silver and releasing oxygen. 2AgCl-+--2Na~CO~-H~0=2Ag-l-2~aCI~2XaHC0 3 +0.

The oxygen thus set free is taken up by the reducing agents, this action being necessary for the continuation of development. In general, the activity of the developer depends more upon the concentration of the alkali present than of the reducing agents themseh·es. These alkalis are called a~ulerators. Since the reducing agents readily combine with the oxygen of the air which is dissoh·ed in the water and at the surface of the solution, it is necessary to add a presert·atire. as sodium sulphite. This reacts with the free oxygen. forming sodium sulphate. If this oxygen in the water were not taken up, the developing reagents would soon be o~idized. lose their reducing or developing power, become colored. and quickly stain the prints. Howe>er. the fogging ability, i e., the tendency to reduce the une.~ed sil>er salts, seems to increase in proportion to the rate of oxidation of sodiunt sulphite. In addition to the preser,·ati>e and aceelerator, the use of a rc#mint'r is al~o neces..~ in de>elopment. Pota.."-.<:.ium bromide is most often used. The presence of thi~ chemical in the de..-eloping solution seems to les..<:en the solubiiity of the sil..-er chloride or silver bromide of the emulsion \\ith a consequent slowing up of development, and a decreased tendency to fog.

DEVELOPMENT

113

CHEMICALS USED.

Developing solutions, then, generally consist of water (the solvent). one or more reducing agents, a preservative to keep the reducing agents from being too rapidly oxidized, an alkali which is the accelerator, and a restrainer. Developing Reagents.-There are a large number of chemical compounds with the ability to reduce the silver salts, removing the chlorine or bromine and dep~siting the metallic silver. However, to be suitable for use as a developer, a reducer must have certain qualities: (1) It must have discriminative action, i. e., under the proper conditions, it must reduce only those grains of the silver salts that have been affected by the action of the light. Some substances would reduce the entire amount of silver salts 'and would therefore be useless since only a uniform black deposit of silver would be formed on the paper. (2) 'It must be nonstaining. A developing agent such as pyro, while very suitabl~ for plates, would under working conditions, so stain the prints as to be objectionable. (3) It should be amenable to control in regard to speed and to the resulting color and contrast of the print, either when one is used alone, or when two or more act together. Metol is a soft-working, and hydrochinon a contrast developer. By the use of both together, the desired results may be obtained. ( 4) It should not be exhausted easily. (5) It should have good keeping qualities. There are some forty or more available reducing agents, most of which are coal tar derivatives. 2 Only the two or three which are most universally used for developing printing papers will be considered here. 2 See Photo-Miniature No. 167: Modern Photographic De1Jelopera.

114

PHOTOGRAPHIC PRINTING

M etol.- (mono-methyl-paramido-phenol sulphate, 2 [ (C6 H 4 ) (OH) (NHCH 3 ) ] (H~S0 4 ). This chemical, a coal tar product, originally introduced by Hauff (1891) as Metol, is now sold under various trade names as Elon, Motol, Pictol, etc. When purchasing metol, it is well to look for the chemical name given above, as well as for the trade name. It is easily soluble both in water and in alcohol. Monomet (para-mono-cresohydro-chloride) works similar to metol and may be used in equivalent amounts. Like other satisfactory developing reagents, metol is a chemical reducer having the property of liberating metals from the silver salts of the emulsion only in the portions affected by light. Since it readily combines with the oxygen of the air dissolved in the water, it soon loses strength. Metol is a soft-working developing agent. The image appears very quickly even in the less exposed portions but density is gained slowly. Used without the addition of any other developing agent, it would give a flat, gray print. Considerable bromide is necessary to have any appreciable restraining action on a developer of this nature. It is not much affected by change in temperature. Metol is slightly poisonous to some skins. Hydrochinon.-(para-dioxy-benzene), C6 H 4 (OH) 2 , is sometimes called hydroquinone or quinol--hence the M-Q for Metol-Hydrochinon developer. Hydrochinon differs from metol in several important particulars. It is sparingly soluble in cold water, but freely dissolves in warm water or alcohol. It has the ability to give great density, the action first taking place in those portions most fully exposed. The image appears slowly but gains density steadily and rapidly. Used alone, it would give a contrasty print, somewhat red in color.

DEVELOPMENT

115

Hydrochinon is affected by temperature much more than rnetol, rapidly losing its reducing power as the temperature is decreased. Potassium bromide acts as a p:>wedul restrainer with this chemical and so is used sparingly. While hydrochinon may be so cornpounded as to give a reasonably satisfactory image, it works best· when used in combination with rnetol as the qualities of the two nicely balance each other. Amidol.-(diarnidophenol hydrochloride) C 6H~OH (NH2) 2 2HCI. This is sold under such trade names as Dionol, Nerol. and Acrol. While not as widely used as rnetol and hydrochinon, it is used quite extensively in some localities. It is frequently used by those who are poisoned by rnetol. Arnidol comes in steel-blue or slightly yellowish needle-like crystals, and is readily soluble in water. It is sornwhat sensitive to temperature, working best from 60° to 65°F. (16° to l8°C.). Bromide in small quantities acts more as a clearer, fairly large amount!'! being needed to cause any restraining action. Arnidol has the p?culiarity of being able to work in combination with sulphite alone without the addition of any alkali. It is one of the best bromide paper developers where a rich blue-black image is desired. Other Chemicals U~.-Sodium sulphite is the chemical used as a preservative in most modern paper developers. It comes in the crystal form, Na 2S0a 7H2 0 and in the powdered N a 2SO ,. It is formed by passing sulphur dioxide gas into a solution of sodium carbonate or washing soda. Crystals of sodium sulphite crystallize out, containing seven molecules of water to each one of sulphite. This crystal variety contains only about 50% pure sodium sulphite so if used in any for-:rnula given in this book, double the quantity called for must be used. If these crystals are dried, a desiccated

i16

PHOTOGRAPHIC PRINTING

variety containing about 95% of the pure salt is formed. A still purer form, the anhydrous salt, containing as high as 98% of sodium sulphite, is obtained by crystallization from hot solutions. Sodium sulphite dissolves readily in warm water and is insoluble in alcohol. It keeps better in concentrated solutions than in a dry state, as it is quite readily affected by the oxygen of the air which combines 路 with it to form sodium sulphate. 2Na2S03 +0 2 =2Na2S04 In the case of crystals, this change to sulphate is readily observed, as a white coating forms on them but the change in the powdered form is not visible. When the cover is left off the sulphite can, a small amount on top is exposed to the air and if there is any dampness present it changes to sulphate. If this is used in the preparation of the developer or fixing bath, the result is far from satisfactory. The trouble is not so much that sulphate is present as that sulphite is absent, although the sulphate is somewhat injurious. The presence of sulphate may be determined by dissolving a small amount of the sodium sulphite in an ounce of water. To this add a little barium chloride solution. If a white precipitate insoluble in weak hydrochloric acid is formed, it is evident that sulphate is present. Sodiurn carbonate is the accelerator used most commonly in paper developers. It is available in three forms: in crystals as Na 2 CO,; 10H2 0 (sal soda) containing about 37% carbonate, and as Na2C0 8 H 2 0 with a little over 85% strength; and in the dry powdered state (anhydrous) about 98% pure. In using the first crystal form, about 2i the quantity mentioned in these formulae should be taken. Washing soda is an impure form of the carbonate.

DEVELOPMENT

117

Sodium carbonate is much more soluble in hot than in cold water and is insoluble in alcohol. The solution should be stirred and the powdered carbonate added slowly or it will cake in the bottom and can then only be dissolved with difficulty. As before stated, nearly all developing agents work only in an alkaline state, their energy depending largely on the amount of alkali present. Alkalis in photographic use are of two types-caustic alkalis as sodium or potassium hydroxide, and carbonated alkalis, as the one under discussion which is a salt of carbonic acid, H 2C03 â&#x20AC;˘ A salt of this sort formed by a weak acid with a strong base gives an alkaline reaction. It is gradually dissociated as it is used up, thus providing a continual supply of a small amount of alkali. In this way, the concentration remains more constant than would be the ease if sodium hydroxide (caustic soda) were used. Potassium bromide (bromide of potash), KBr, occurs as white cubical crystals, very soluble in water, especially if the water is warm. It has two primary functions in the developer: (1) It acts as a restrainer, preventing too rapid development and fog. (2) It controls to a large extent the resulting color of the print, a greater quantity producing a more olive-toned black and white print and a warmer-toned sepia. Cleaning Solution.-Before beginning development, care should be taken that bottles, trays, and other laboratory equipment are chemically clean, or solutions may be affected and partly spoiled, causing much trouble in the production of good prints. The following cleaning mixture will be found very efficient: Potassium dichromate (commercial) Water Sulphuric acid (commercial)

H oz. or 35 gr. 10 oz. 300 c.c. 7l oz. 220 c.c.

118

PHOTOGRAPHIC PRINTING

Dissolve the potassium dichromate in warm water. Cool slightly, and with constant stirring slowly add the sulphuric acid. After cooling, transfer to a widemouthed bottle which is most convenient for storage. It will be quite efficient even if diluted for use with one to three parts of water. Pour this solution into the bottle or tray needing cleaning, shaking in case of the bottle and rubbing with cloth or cotton in case of a tray. (Caution: Mixture must not come in contact with the skin or clothing.) After the equipment is clean, pour the solution back into the wide-mouthed bottle to keep for use again. METOL-HYDROCHINON DEVELOPER.

This developer has been more largely used than any other in this country. The formulae given by manufacturers of the various printing papers are usually best adapted for those papers since they are adjusted to meet any special individuality in composition. However, the majority of formulae recommended vary so slightly that a good standard one will ordinarily give good results. As a matter of fact, if most of them are reduced to grains per ounce or grams per liter, it will be noted that the variation is almost negligible. This proportion is given in connection with the standard formula below in order that comparison may easily be made with other formulae if desired. Stock Solution.-The quaptity suggested will nearly fill a quart or a liter bottle, an amount which is well adapted to most small studios. (Note: In converting to metric or avoirdupois, the smaller fractions having no appreciable bearing' on the photographic results have been dropped).

DEVELOPMENT Water Metol Sodium sulphite~ HydrO'Chinon Sodium carbonate:~

119

After Dilution Graina per Grams per 30 oz. or 900. c.c. ounce. liter. 22~

gr. 2 oz. 90 gr. 2 oz.

1.5 22. 6. 22.

g. g. g. g.

.97 5-47

1.5 5.47

.83 l:e.! 9.9 1ft.S

Fm路 use with most papers, dilute with an equal amount of water. Potassium bromide is added when ready to develop, the amou路nt depending on the effect desired. Ordinarily, chemicals should be added in the order listed. However, if the metol is dissolved first, especially if the water is warm and contains very much dissolved air, considerable oxidation may take place before the preservative is added. But if the sulphite shouid be dissolved first when mixing up concentrated solutions, the metol might refuse to dissolve. Hence the correct method is to weigh out both the metol and the sulphite, first dissolving a small amount of the sulphite, then the metol, and then the remainder of the sulphite. After this the hydrochinon and sodium carbonate are dissolved in turn. Constant stirring while the carbonate is added slowly will prevent the formation of a hard lump which would take a long time to dissolve. Sometimes it is preferred to mix up a concentrated solution which will keep somewhat better and require less storage space. However, there is a definite limit to the possible concentration of the developer. Those who wish to make the more concentrated solution will find that the addition of alcohol up to 10% is advisable, since the reducers which have the greatest tendency to crystallize out on cooling, are soluble in alcohol. But the alcohol should be added after the chemiculs are dissolved as much as pos路sible, as it rather lessens the solubility of the other chemicals. 3

The powdered (anhydrous) form should be used.

i26

PHOTOGRAPHIC PRINTING •

· Modification of the Developer. Local conditions as impurities in the water or chemicals, or a desire for different effects in contrast or tone often make sligl1t modification necessary. Besides this, many times, the usual developer may be too soft or work too contrasty for the negative and the available papHr. Increasing 1.5 ,.., the metol and decreasing · the hydrochinon by the same proportional amount \.\.. t..l will give softer effects. This \.t ""' \.t may be further modified by ... ... decreasing the accelerator by one (sodium carbonate) ., half the usual amount. This ,, naturally gives a slower working developer. On the other hand, increasing the hydrochinon perhaps a half and decreasing the metol in the same proportion will give more contrast. This must not be carried too far or the prints will come up reddish in the d€veloper. On some/ papers the carbonate can be increased as much as one half, but too great an addition will cause too rapid de(a) (b) velopment with a decided Figure 30. tendency to fog. Strips developed in (a) Soft The amount of preserva(b) Contrast Developer. tive necessary (sodium sulphite) depends largely on the amount of water, and should remain constant.

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121

•

Soft-Contrast Formula. One of the most convenient methods of modification is to have at hand a soft and a contrast developer of such proportions that mixing equal parts will form a normal developer. ·

.9oft.

W·a ter Metol Sodium sulphite Hydrochinon Sodium carbonate

Contrast.

30 oz. or 900. 33l gr. 2.3 ~ oz. 22. 45 gr. 3. i oz. 11.

c.c. g. g. g. g.

30 oz. or 900. 111 gr. .7 ~ gf'.o~ . 22. 135 gr. 9. 1~ oz. 33.

c.c. g. g. g.

For a normal developer, use equal parts of each; if soft or contrast effects are desired, use the devel-

•

Figure 31. Developed in Soft Developer.

Figure 32.- Developed in Contrast Developer.

oper specified. Dilute with an equal amount of water in all cases. For less decided results, use proportional amounts of each, e. g., Ji soft and % contrast or % soft and ~ contrast, adding equivalent amounts of water. l

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PHOTOGRAPHIC PRINTING

Figure 30 shows test screen strips developed in the two developers: (a) soft, (b) contrast. Examples of prints made according to the two formulae are seen in Figure 31 and 32. A satisfactory way to store this developer is to keep it in full tightly-corked bottles small enough that the contents may be used within a week anyway. A more convenient method of storing is to have the t'vo solutions in receptacles with floating lids which al'e both acid and alkali proof. This permits of larger

â&#x20AC;˘

Figure 33

Two-Solution Storage Device.

quantities being prepared, as oxi,d ation is thus reduced to a minimum. By having the two. containers so arranged that both of them flow into a burette, the Ineasurrment of amounts is made easy. (Figure 33.) Three-Solution Developer. For those photographers who prefer a three solution developer, the following formula is given. As the carbonate is separate from the developing agents and as there is some preservative with both the metol and the hydrochinon,

â&#x20AC;˘

DEVELOPMENT

128

the solutions will keep for a long time. However, they are more troublesome to prepare. Three bottles are required. A B c Water路 ' 10 oz. or300.c.c. 10 oz. or 300.c.c. 10 oz. or 300.c.c. Metol 221 gr. 1.5 g. Sodium sulphite i oz. 11. g. i oz. 11. g. Hydrochinon . . . . . . 90 gr. 6. g. Sodium carbonate...... ! oz. 22. g.

A small amount of alcohol may be added in case difficulty is experienced in getting the brand of metol used to dissolve. The following proportions will give developers of the same contrast as obtained by the method already described: For Soft developer Contrast developer Normal developer

Use A 3 parts. 1 part. 1 part.

B C Water 1 part. 1 part. 7 parts. 3 parts. 3 parts. 5 parts. 1 part. 1 part. 3 parts.

More or less of any of the solutions, within reasonable limits, may be used to get the desired results. Developing the Print.-Preparation. Four trays, containing respectively developer, short stop, fixing bath (to be discussed later), and water, arranged in that order, should be 1路eady before starting to print. Developing trays should not be decidedly larger than the prints, as an unnecessarily large surface of the developer exposed to the air results in more rapid oxidation and consequent exhaustion. The developing must be carried on in a safe light, yellow or orange, depending on the sensitiveness of the paper used. Use of Potassium Bromide.-A .saturated solution of potassium bromide should always be at hand in the printing room as most developers cause fog if no restrainer is used. Enough of this must be added to the

124

PiiOTOGRAPHlC PRINTING

developer to prevent the reduction of the unexposed silver salts (which causes the fog) during the time the print is in the developer. Beyond this amount, it may be added in sufficient quantity to give the color desired, .the minimum amount resulting in cold blueblack prints, which if toned will tend toward the purple. An excess will give an olive black and white, and a yellow sepia. For normal effects, 1 drop of a saturated solution of bromide to each working ounce of developer will be found satisfactory (about 3 drops to 100 c.c.). In some localities the water may contain sufficient restrainer that no addition of bromide is necessary. Effect of Humidity.-Paper should preferably be developed immediately after exposure. In case the prints are made several hours before being developed. they must be stored in a dry place as a few hours of dampness may result in partial or almost complete destruction of the latent image, giving the appearance of decided underexposure. This effect will be aggravated if the paper is moist a:t the time of printing. Excessive moisture in the paper at this time or before developing will often result in a mottled appearance of the image. The results may often be improved by drying out the paper before using. Temperature of Developer.-Most printing papers work best at a temperature of 65°F. (18.3°C.) ; a few at 70°F. (21.1 °C.). From what has been learned of the characteristics of metol and hydrochinon, it is readily seen that to lower the temperature decidedly will soften the contrast, tending to give a flat, gray print. This is because hydrochinon is more affected by temperature than metol is, almost losing its activity at 40°F. (4.4°C.), thus resulting in metol doing more than its share of the work. Conversely, a decided rise in temperature will increase the contrast as the hydrochinon then becomes most active. Too great an increase, however,

DEVELOPMENT

125

not only softens the emulsion but may result in fog; which by giving a deposit of silver, makes the highlights gray and tends to flatten them. If the temperature cannot be kept down and prints develop too fast, it may be advisable to reduce the amount of carbonate. The temperature of the developer should be tested occasionally. Since a printer gets used to developing prints for a certain length of time, if the temperature is decreased without his knowledge, the tendency is to increase the exposure so as to get them developed in the usual time. This naturally results in overexposure and consequent underdevelopment, giving muddy, mottled black and white prints, and yellow sepias. A convenient method of keeping the temperature uniform is to have a connection from a cold and a hot water faucet to a large tray in which the developer tray is set. By keeping a small flow of water of proper tPmperature through the large tray, the temperature of the developer may be kept constant. Another good method is to have a suitable box built into and under the sink, covered with a thin piece of soapstone or slate. In summer, this is used as an ice-box; in winter, a lamp or electric light may be placed underneath. The developing tray resting wholly or partially on the top will be easily kept at the desired temperature. Process of Development.-Complete development is attained when all the particles of light affected silver salts have been reduced to metallic silver. Most portrait papers are so made that in the proper developer at the correct temperature, they will be fully developed in 1! to 2 minutes. Commercial and amateur papers in their special developers more often develop in 20 to 40 seconds. Development for a definite time is not the method to be preferred, except for beginners. The developer may gradually cool down, become partially exhausted.

126

PHOTOGRAPHIC PRINTING

or have some acid or hypo dripped into it. All of these things would slow it down. resulting in the later p1'ints being lighter, while if the temperature were increased in any way, the prints would be darker. In order to get the print immersed evenly and quickly, tip the tray to one side. Slide one edge of the print, face up, into the developer, and tipping the tray to the other side, flow the solution quickly over the entire print. Prints must not be held up for examination for more than a few seconds during development or yellow stains may be formed. This is caused by the thin film of developer on the surface of the print being rapidly oxidized by the air, with discoloration and a staining of the print. The same thing often happens when one end or corner of the print sticks up out of the developer. I't is best to leave the print in the tray, which should be slowly rocked to secure eveness in development, until within 10 to 15 seconds of the time it should be done. While holding it up to drain, examination wilJ disclose when development is completed. The novice will find one or two prints at a time all he can handle while the professional will develop upwards of a dozen. A correctly exposed print is properly developed, if it reaches the desi::ed depth at the instant development stops (seems to pause), having built up gradually to this point. It does not seem to darken any further but it will build up in quality and take on an added brilliancy for a few seconds more. At this point it should be placed in the short stop bath, as further action by the developer will soon cause the development of the unexpo~ed silver salts with consequent fog or veiling over the highlights. (Figure 35.) The variation in the color and intensity of the printing room illumination often makes it difficult to

DEVELOPMENT

127

judge when prints have reached the proper depth. A correctly exposed and developEd print, mounted on rrlass with the emulsion squeegeed down to the glass and waterproofed, will be of considerable value to have at hand for comparison when developing. Then, too. p~.pers usually appear. darker in orange light than in daylight, and many kinds dr·y out darker, so allowance · must be made for these factors. The contrast of chloride papers is not materially affected by variation in exposure and development. Nu.turally, though, considerable underexposure would result in a lack of deposit, giving chalky highlights which would apparently increase the contrast, but the disagreeable effects would more than counterbalance any gain. Variations in Developer.-Increase of bromide in the developer slows it down. The tendency then is to overexpose and develop for the usual time, thus causing underdevelopment resulting in too warm tones. In ~·eneral an increa3e in bromide should be followed by p~·olonged developm:nt rather than by longer exposure. As the bromide is increased, the developing action is retard:d, the silver is more slowly deposited and in a finer state of division, resulting in a print with more color. With no bromide, the fog free period is less than 15 seconds with most papers. One drop to the ounce extends it to 2 or 3 minutes, while the addition of a sufficient amount may lengthen the time to 15 minutes or longer on some papers. If the metol, hydrochinon, and carbonate are varied, the time of development should remain about the ::;arne, any change necessary being made in the length of exposure. Local Development.-Occasionally a print may be improv€d by locally developing certain portions more rapidly than the others. A light dress or one side of

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DEVELOPMENT

129

the face may come up chalky. In order to develop that portion to the proper depth the print must first have had ample exposure as silver salts not affected by the light can not well be developed. Develop the print in normal developer until the image is just visible and then immerse in water. Now holding the print out of water, apply with a soft camel's-hair brush or cotton some full strength developer, containing little or no potassium bromide, to the chalky portion. Quickly immerse in water so as to leave no sharp streaks where the strong developer acts. Repeat this process until the parts that have been too light have reached the required depth. Finish developing in the regular developer. Caution must be used that the print does not remain in the air long enough to receive oxidation stains. Development to Secure Softness.-Potassium iodide may be added to the developer in small quantities, about ! grain or less to the working ounce, to increase the softness of the print. As it has a considerable tendency to flatten the print, not much should be used . .The iodine turns the print somewhat of a canary yellow color but this dissipates by the time it has been thoroly fixed. 路 Increased softness may also be secured by soaking the print for a minute or longer in water after exposure before development. As this tends to destroy the latent image, the print to be treated in this way must have had more than the normal exposure or it will appear too Iigh t. Defects in Development.-Underde11elopment of correctly exposed paper will naturally givP. prints that are too light. If, however, the paper is overexposed, the print flashes up quickly, is full of detail, and rapidly gets too dark. If development proceeda further, \~ b~om~s so dark as to be useless. If action is sto:t>ped~

130

PHOTOGRAPHIC PRINTING

the print is muddy in appearance and is often mottled. 4 The deposit of silver is thin, and if toned, the sepia is a sickly yellowish color. The remedy for this is to cut down the exposure and give longer development. Overexposure and underdevelopment is the great fault not only with beginners but with many others. (Fi:gure 36.) Overdevelopment results when prints have had insufficient exposure. The print comes up slowly, is cold or weak in appearance, and if forced too long, development will start in the unexposed silver salts, resulting in a filming over of the highlights, perhaps with a grainy aspect. (Figure 34.) The sepia from such a print is usually of a weak purple tone. No Development.-In this case, either the developing agents (metol and hydrochinon) or the accelerator (the carbonate) have been omitted. (If the print comes up contrasty and is of a reddish color, the indication is that the metol has been omitted and that the hydrochinon is doing all the work.) Fog, as has been mentioned, is caused by forcing too long in the developer without sufficient bromide. It may also be caused by the use of old or discolored developer. A further discussion will be given in Chapter XV on D~fects. Impurities in Developer.-The most common trouble along this line comes from getting some of the short stop bath containing acetic acid or of the fixing bath containing hypo, into the developer. The acid neutralizes the alkaline sodium carbonate with the result that the develoner is quickly reduced in energy. Pure hypo, however, in very small quantities will cause the print to appear a little more contrasty. The hypo starts the fixation of the silver salts, and in the high4Prints often soak up enough water in spots to appear mottled by transmitted light. This should cause no alarm as on drying the spottiness disap1>ears.

. 1

DEVELOPMENT

181

lights where there is but little deposit, this action may remove enough to cause them to appear considerably lighter in tone. One grain to 10 ounces of developer is about all that can be safely used in this manner. This method while useful in an emergency is not to be recommended for general use as it is very likely to cause yellow stains. The same thing happens when any of the hypo from the fixing bath gets into the developer. Exhaustion of Develope1路.-This is ascertained by the slowing up of development and the red color of the prints when they first appear. If they do not turn a good black by the time development is complete, the developer should be discarded. AMIOOL DEVELOPER Metol is poisonous to the skins of some persons. For them and others who may prefer amidol, the following formula will be found satisfactory: Water Sodium sulphite Potassium meta:bisulphite Ami dol

20 320 120 60

oz. gr. gr. gr.

500. 17.5 6.5 3.3

c.c. g. g. g.

Add bromide as needed. Dilute the developer for softer effects. Since amidol does not keep well, it may perhaps be better to add the amidol at the time of development as it quickly dissolves. Potassium metabisulphite may路 be omitted in that case. Citric acid may be used as a preservative instead of the potassium metabisulphite. Amidol is perhaps without an equal as a developer for bromide papers. It works rapidly without fog or stain, giving a brilliant blue-black tone. Papers that tend toward a yellow sepia had best be developed with amidol, as this tone of black and white will give a colder-toned sepia.

CHAPrER XII. FIXATION. CHEMICALS.

Some knowledge of the chemical constituents of the short stop and fixing bath is necessary in order that they may be prepared and used to secure the best results. The chemicals are discussed in the order added to the bath so that the student may become accustomed to this order. Hypo (sodium thiosulphate)t, Na 2S20& 5H 2 0. Hypo comes on the market in large, clear crystals, which should be free from acid or any yellowish tinge. It is soluble in the proportion of 1 part to 2 parts of cold water, and 1 to 1 of boiling water. It can be formed by heating together sodium sulphite and sulphur, (Na2 S03 +S=Na2S 2 0 3 ) , but is usually prepared commercially by treating calcium thiosulphate with sodium sulphate. Most acids as hydrochloric, sulphuric, etc., break up路 the hypo with the liberation of sulphur, forming a milky bath. (See Note2)

(1)

H 2 S 20 8 +2NaCl hypo hydrochloric acid

thiosulphuric sodium acid chloride

(2)

H2s20a thiosulphuric acid

H 2S03 +S sulphurous sulphur acid

1 Hypo is often wrongly called "Hyposulphite of Soda". Such a compound would 'have the formula Na2 S0 2 and very different properties. 2Thisisoftengiven Na,S 2 0 8 +2HC1=2Na.Cl+H~O+SO~+S.

FIXATION

133

Sulphurous acid, however, is an exception as it does not cause the liberation of sulphur. In photography, the principal function of hypo to act as a solvent for the silver salts.

Sodium Sulphite.-This has already been discussed in the chapter on developers. Its use in the fixing bath is two-fold: to prevent the oxidation of any developer that may be carried over into the fixing bath, and in connection with the acetic or other acid used, to form sulphurous acid which does not affect the hypo. Acetic Acid, HC2 H3 0 2 , is a colorless liquid, sour to the taste, and with a pungent smell. It is usually prepared from the products obtained from the destructive distillation of wood. It is the acid of vinegar and is there formed by bacterial action or fermentation of cider. . Two grades are commonly made use of in photography: glacial (strength about 99%) and a commercial grade of 28% strength which is the one most generally used. Its purpose is to check development by neutralizing the alkali. Being a weak acid, more can be used in the fixing bath than in the case of a strong one. Citric acid is sometimes used as a substitute. Alum.-There are a number of varieties as ammonium, chromium, iron, and aluminum alums. A form of the one last named, aluminum potassium sulphate (commonly known as potash alum), is most often used in acid fixing baths. 路The chemical formula is Al 2 (S0 4 ) 3 K2 SO; 24H 2 0. Its function is to harden the gelatine and so prevent frilling, blistering, and similar troubles. In sepia baths it not only has a hardening action but it also reacts with the hypo to liberate sulphur as no sulphite is present. If potash alum is not available, sodium, ammonium, or chrome alum may be substituted in preparing

134

PHOTOGRAPHIC PRINTING

the fixing lY.dth. Chrome alum has a slightly greater tendency to precipitate sulphur. SHORT STOP BATH.

Advantages.-Prints when removed from the developer may be rinsed in water and then placed in the fixing bath. This method, however, has three disadvantageK: (a) Developing action continues and if the print ~~,, overexposed, it becomes too dark before reduction is Ktopped by the fixing bath. (b) It is necessary to place the prints one at a time in the hypo as they are developed, resulting in extra work and making it more difficult to keep track of the length of time each has been in the fixing bath. (c) Considerable alkali is carried over to the fixing bath, causing it sooner to become worthless. To overcome these troubles it is only necessary to have a tray of acidified water convenient to the developing tray into which the prints are plunged as soon as development is complete. They should be slid in face up and soon turned over. This treatment is less likely to result in the formation of air bubbles with consequent prolonged development in those places, which would result in darker spots. By using a print paddle the prints may be pushed beneath the acid and tumed over without the fingers touching the liquid. Any acid on the hands would have to be removed before developing more prints as its introduction into the dewloper would slow down its action. J4'oa路mula: Water 32 oz. Art>tlc arid (28'#路 ):1 U oz.

1 liter (1000 c.c.) 50 c.c.

aif aretic acid is not available, one-third the amount of cit1路lc acid may be ul!ed as a l!Ubstitute.

186

fiXATION

The bath may be used as long as it remains acid. This can be determined by testing with litmus paper. Its chemical action is to neutralize the alkaline sodium carbonate. Na 2 C03 +2HC 2 H 3 0 2 = ..2..NaC 2 H 3 0 2 +H 2 0+C0 2 sodi\un acetic acid carbonate

sodium acetate

water

carbon dioxide

The use of a developer strong in carbonate and a short stop or fixing bath strongly acid will therefore rapidly liberate carbon dioxide gas, with a tendency to form blisters. If trouble is experienced with blisters appearing during fixing or afterwards, the prints before being washed may be placed for five minutes in a hardening bath, such as the sepia hardener described in Chapter XIV. FIXING BATH.

In the early years of photography, it was possible to secure an image on a suitable support, but to retain that image so that it would not fade on exposure to light remained a problem for some time. Potassium cyanide was finally found capable of removing the unexposed silver salts, but because of its extremely poisonous nature, it was later discarded in favor of hypo. Chemistry of Fixation.-Sodium thiosulphate, or hypo as it is commonly known, has the property of being able to dissolve silver chloride and other similar salts. As has already been seen, part of the silver salts is reduced to metallic silver during development. The silver salts which have not been affected by the light and therefore not developed, would, if allowed to remain in the emulsion, tum pink and thell dark C)8

186

PHOTOGRAPHIC PlUNTING

exposure to light, so that in a short time the image would become invisible. If the print after development is placed in a hypo solution of proper strength for a time, the remaining silver salts will be removed and the print which will then be permanent is said to be fixed. If the bath becomes worn out so that hypo is present in too restricted a quantity, the following reaction takes place: AgCl silver chloride

Na 2 8 2 03 sodium thiosulphate

AgNa8 2 0 3 silver sodium thiosulphate

NaCl sodium chloride

This double thiosulphate is only slightly soluble in water and its elimination is a matter of extreme difficulty. If, however, the fixing bath is of the proper strength, this compound, if formed, will immediately re-dissolve in the hypo so that the final result may be expressed as follows: 2AgC1+3Na2 8 2 0 3 =Ag2 Na, (8 2 0 3 ) 3 +2NaCl The double thiosulphate, Ag2 Na, (8 2 0 3 ) 3 , here formed is very soluble in water and can easily be removed from the emulsion by washing. In the case of negatives, the end of the first stage is reached about the time the plate is cleared of the milky deposit. If taken out of the bath at that time, the insoluble and invisible compound can not all be removed by washing, resulting in a later decomposition of the image. Leaving the plate in the hypo for double the time it takes to clear it, changes the insoluble compound to the soluble form. The end of the first stage in the case of the print, however, cannot be determined by inspection, so it is most important that the bath should be of the proper strength, not overworked, and that prints are left in it for a sufficient length of time.

18'7 Acid Fixing Bath.-While a :fixing bath must not be weak, neither will one containing too large a quantity of hypo be satisfactory, as not only will the rate of fixation not be appreciably increased, but there will be a tendency to bleach the image and possibly cause blisters. It should not be stronger than one ounce J' of hypo to two and one half ounces of water, or fifteen grams to seventy-five cubic centimeters. The following formula while not the same as recommended by all manufacturers, will nevertheless be found satisfactory for most developing papers. For convenience, the quantity given is such as may be stored in a gallon bottle. A

Plain Fixing Bath. Water Hypo

~ gal. (96 oz.) U Ibs. (24 oz.)

or 3. liters (3000 c.c.) .7 kg. ( 700 g.)

B Hardening Bath. Water 8 Sodium sulphite (powdered) H Acetic acid (28%) 4~ Alum (powdered) H

oz.

250.

oz. oz. oz.

40. g. 140. c.c. 40. g.

c.c.

Where a large amount of work is done, it is advisable to mix the hardener in larger amounts and keep in a corked bottle or covered crock. When ready to mix the fixing bath, dissolve the hypo in the proportion indicated, and add one eighth of that quantity, of the hardening bath. Method of P'reparation.-(See Experiment 5.) Part (A) should be thoroly dissolved before (B) is added or sulphur may be precipitated and the bath become milky. As hypo going into solution causes a decided drop in temperature, and a slowing up of the rate of further solution, it is best to use reasonably warm water. But if too warm, especially when the hardener is added, the bath, even if it clears at first, will usually

188

PHOTOGRAPHIC PRINTING

turn milky within a few days and become worthless. In mixing the hardener, it is better to dissolve the alum and the sulphite each in half the water, which should be warm. Cool and add the acid to the sulphite, and then add the alum solution. Satisfactory results are usually attained, however, by adding the sulphite, acid, and alum to the water in the order given. This is then added to the hypo solution. If the chemicals were added separately to the hypo, the bath would be more or less decomposed. If the acid were added first, the hypo would be sulphurized. Sulphur once precipitated will not combine with sulphite under these conditions. To prevent this, the acetic acid is mixed with sufficient sodium sulphite to combine with all of it, forming sulphurous acid which does not liberate sulphur from hypo. If the sulphite were added first to the hypo, and then the acetic acid added, there would be a certain amount of sulphurization because of a local excess of acid. If the sulphite and alum should be dissolved together before adding the acid, a white sludge of aluminum sulphite might be formed which dissolves with difficulty. Milky fixing baths may result from several causes, the principal ones being: (a) Too much or too strong acid in the hardener.. (b) Insufficient sulphite. This may be caused by some of the sulphite having been oxidized to sulphate which will not prevent the acid from sulphurizing the hypo. In practise, too, there may be sufficient excess acid carried over from the short stop bath to cause sulphurization, especially if the temperature of the fixing bath is high, as in that case the ordinary amount of sulphite is not enough. (c) Omission of sulphite. Hypo without being protected by sulphite would also release sulphur by the action of alum, which in combination with water forms sulphuric acid.

li'IXATION

189

(d) Addition of the hardener before the hypo is all dissolved or at too high a temperature. (e) Improper mixing, as adding the acetic acid directly to the hypo solution. (f) Insufficient acid in the hardener which may result in a milkiness that settles in a few hours. 路The white color in this case is caused by the formation of aluminum sulphite. Results of Milky Bath.-When some of the hypo is broken up and sulphur is released, two things have happened. (1) To that extent, the bath is weakened and the prints may be insufficiently fixed and therefore will probably fade in time. (2) The released sulphur, especially in warm weather when the temperature of the fixing bath is increased, is likely to combine with the silver of the prints, forming silver sulphide, and resulting in a partially toned print. Under favorable conditions, a partially sulphurized bath may properly fix prints and also slightly tone them. But more often the sensitive silver salts are not entirely eliminated. If prints are found which are starting to tone, remove them to a fresh hypo bath to insure propzr fixation and then sepia them to secure a uniform color. Action of the Hardener.-Altho a plain hypo bath is all that is needed to thoroly fix a print, yet it is seldom used, as prints are more liable to soften and frill or blister, and also to become discolored. As already stated, the sodium sulphite not only prevents oxidation but, acting with the acetic acid, forms sulphurous acid which does not affect the hypo. It also prevents the alum from liberating sulphur from the hypo. The acetic acid neutralizes any alkaline carbonate which may reach the fixing bath and so stops development. To that extent it acts as a hardener, as an al- . kaline bath would soften the gelatine. By u~ing a weak acid, it is possible to take a considerable quanti,ty

140

PHOTOGRAPHIC PRINTING

so that it will not soon be exhausted. A strong acid would have to be used in such small quantity that its action would soon stop. The alum, used as a hardener, works best if slightly acid. Use of Fixing Bath.-When prints are removed from the short stop bath, they should be drained for a few seconds and then slid into the fixing bath face up, as air bubbles are then less likely to occur. These would hinder proper fixing at those places. If the bath is fresh, the prints will be fixed in ten minutes but fo1路 safety it is advisable to leave them in for fifteen minutes. A longer time is not desirable as too long an immersion is liable to result in a slight reduction or bleaching. Also, if the bath is warm, the tendency for the gelatine to soften and for the prints to be discolored if any sulphur is present, will be aggravated. During the time the prints remain in the bath, they should be separated a number of times to insure sufficient fresh hypo reaching all the silver chloride to remove it. Failure to do this will result in a gradual fading of the prints. Capacity of Bath.-No definite rule can be given as to how many prints a given quantity of bath will fix. This is because the amount of unexposed silver chloride or silver bromide found in prints is not uniform. Prints in a low key with dark or black backgrounds have but a small amount of silver salts that has not been reduced by the action of the light and developer. On the other hand, vignettes have a disportionately large area of white surface where there has been no reduction of silver salts. Since these must all be l'emoved by the hypo, a la~路ge amount is needed. The following table indicates the limit for the number of prints that may be fi."'Ced in 1 gallon (about 8.78 liters) of fixing bath, giving an assunmee of permanency.

FIXATION Size 4x5 3i11x5i 4x6 b7 5x8 6ix8i

Number of prints Size 532 7xll 500 8x10 440 10x12 ~ 1bu 270 12x15 196 14x17

141 Number of prints. 142 108 86 ro 60 46

A record of the number of prints put thru the bath should be kept and when the number indicated is reached, the bath should be discarded. Exhaustion of Bath.-(See Experiment 14.) There is no definite test that may conveniently be performed by the photographer to indicate whether the fixing bath has reached its limit, as the absolute limit is so variable a factor. A bath when discarded usually has a considerable amount of hypo still available, but as has been described, when the bath is too weak, there is formed a certain amount of the double thiosulphate compound which cannot be removed by washing. Also, even if the bath is still working, enough oxidation products from the developer may be present to cause discoloration and stain. Again, the alum may become exhausted, causing the prints to soften and frill, even tho the hypo bath may still be active. If a bath becomes frothy when violently agitated, it is a sign that it is becoming exhausted and should be discarded. Another simple test4 is to immerse a piece of bromide paper (not exposed or developed) in the fixing bath for the usual length of time. Then place it directly in a sodium sulphide solution, such as is used for redeveloping. If not fixed at all, such a strip would rapidly turn a dark brown in the sulphide solution. So if it discolors, it is evidence that it has not been sufficiently fixed and that the bath which is working too slowly should be discarded. British Journal of Photography, March 3, 1922, p.

1~2,

CHAPTER XIII. WASHING AND DRYING. WASHING PRINTS.

Necessity.-Prints when removed from the fixing bath, contain in the gelatine and in the pores of the paper a number of chemicals. Not only is there the hypo, sulphite, alum, and sulphurous acid of the fixing bath, but also silver sodium thiosulphate and sodium chloride (products of the reaction of hypo and silver chloride), and possibly some of the developing chemicals, including their oxidation and reduction products. If all these are not thoroly removed, it is only a question of time before the prints will fade or become discolored. In case a weak or nearly exhausted fixing bath has been used and the nearly insoluble variety of the double thiosulphate formed, satisfactory washing of the prints will be much more difficult if not impossible. Temperature of Water.-As salts dissolve and diffuse more rapidly in warm water, it would seem that prints could be more quickly washed by increasing the temperature of the wash water. However, this would cause the emulsion to swell which would to some extent prevent diffusion, so there is no decided gain. It is more important that the temperature of the successive changes of water remain constant, since a decided change, especially from cold to warm, is likely to cause blisters. The reaction between the sodium carbonate of the developer and the acid of the short stop or fixing bath formed some carbon dioxide gas. If either air or this gas 'is imprisoned in the gelatine, a

WASHING AND DRYING

143

sudden increase in temperature is likely to cause suf. ficient expansion so that the pressure will cause raised spots or blisters. Methods.-(See Experiment 18.) The removal of the hypo and other soluble chemicals from the prints is effected by diffusion. By this is meant the tendency of the particles or molecules of different liquids to intermingle and form a homogeneous solution. In this case the particles of water slowly penetrate or diffuse into the porous gelatine and at the same time the solution of hypo with its impurities diffuses out into the wash water. In addition, the chemicals must also be washed out of the paper stock on which the emulsion is coated. The removal of the impurities, therefore, is rather a slow process and cannot be hurried by using a strong flow 9f water, or by violent agitation. W asking by hand is more laborious but more certain of results than most methods. The prints are placed in a tray of water and aftel' three or four minutes are transferred, one at a time, to a second tray of water. The first tray is refilled with fresh water and the process repeated until the prints have been in ten to twelve changes of water. Running Water.-If prints are placed in a tray and water allowed to run in and then out, very little good is accomplished, as hypo, being heavier than water, settles to the bottom on the prints. 1 Also, the prints, being in contact with each other, are almost certain to have spots where the chemicals have not been removed, even after several hours washing. Too strong a stream of water falling on the prints may crack the emulsion, cause blisters and other damage. Commercial Washers.-A number of automatic washers are available, many being quite efficient. (Fig1 If this method must be used, a siphon to automatically remove the water when the tray fills up, will be a great help.

•

144

PHOTOGRAPHIC PRINTING

ure 37.)

However, some kinds do not sufficiently remove the hypo-laden . water from the bottom of the washer while others do not keep the prints properly separated. Preferably the washer should be provided with a sipho~ arrangement to remove By courtesy of Burke & James, lnc. water from the botFigure 37 Commereial Washer. tom of the tank. •

•

· Time of Washing. As the hypo and other chemicals are removed by a slow diffusion, half is found to be removed in a given length of time. This takes from two to·three minutes for negatives but longer for prints. In as much longer time, half of the remaining hypo is removed. As this process of continually removing half of what is left keeps up, the amount remaining in an hour is infinitesimal. By test, no appreciable amount of hypo is found at the end of ten changes or after forty-five minutes in running water, if the prints do ·not become matted together. For safety, however, it is advisable that prints receive twelve changes of water, or rem·a in separated in running water for an hour. •

Tests for Hypo. (See Experiment 17.) By the use of any. one of a number of tests, the photographer can convince himself as to when the hypo has been sufficiently eliminated. While this is not necessary with every batch of prints, it is very desirable to check up on conditio11s occasionally, especially when any new system of washing or type of washing machine is being tried. In hot weather, when excessive washing may ~nduly soften the gela:tinet it is worth while tQ

•

WASHING AND DRYING

145

make tests to see how soon prints may safely be removed from the wash water. Taste is the simplest test. If there is much hypo present, the water on the prints will taste salty. Potassiu,rn Permangate Test.-Make up a stock solution by dissolving about 4 grains (.25 grams) each of potassium permangate and sodium hydroxide in 4 ounces (120 c.c.) of water. If three or four drops are added to a test tube or graduate of water, the color will be a decided pink. Just a little water should be used and only enough of the stock solution to get a light pink or it will not show the presence of a minute quantity of hypo. Now remove a few prints from the wash water, and after draining for an instant, allow the remaining water to drip into the glass of permanganate solution. If hypo is present, the potassium permanganate (pink) will be changed to potassium manganate (greenishyellow or nearly clear). If the color of the solution is not appreciably changed by the drippings from several prints, the hypo may be considered to be sufficiently eliminated. Silver Nitrate Test.-Collect the drippings ftom several prints in a test tube. Heat and add a drop of silver nitrate solution. If hypo is present even to the extent of one part in several thousand. it will be detected by a dark precipitate of silver sulphide. Iodine Test.-A piece of starch a little larger than a pea is boiled in a small amount of water (! oz. or 15 c.c.) until the solution is clear. To this is added a few drops of a solution of iodine. This produces a very blue liquid, a very little of which will impart a blue tinge to a test tube of water. The prints as in former methods are drained into it and if hypo is present, the blue color will instantly disappear.

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Hypo Eliminators are generally unsatisfactory. They remove the hypo by oxidation to sulphates or other compounds. Some bleach or otherwise injure the prints, and the compounds formed by their reaction with hypo are about as difficult to remove as the hypo itself. The following method is probably as good as any. Immerse the print in a very dilute solution of potassium permangate, slightly acidified with sulphuric acid to lessen staining. When the solution becomes discolored, place the print in a fresh solution. When no further discoloration takes place, the hypo has been entirely eliminated. If the prints should become discolored it may be necessary to add a drop or two of hypo solution. All in all, plenty of fresh water is the best elimi路nator. Non-Removal of Hypo.-If hypo remains in a print to any extent, trouble may be expected in a short time. If a large amount is present it will soon appear as small white crystals on the surface of the print. If, however, only a small amount remains, the print may last for years, only to finally become discolored. Hypo is not very stablr, and in time is liable to break down with the liberation of sulphur, forming yellow spots on the print. DRYING.

Rate of Drying.-Extremely rapid drying is not considered best for the highest grade of work, especially in portraiture. Prints on most papers lose brilliancy and seem to lose color on drying. These conditions are appreciably increased if quickly dried by heat, the prints taking on more of a dead-matte finish and tending to lose the slightly olive tone that is usually considered more pleasing than a decided blue-black. Most amateur finishing as well as a great deal of commercial work must be turned out in quantity with-

WASHING AND DRYING

147

in a short time. Hence a certain amount of quality must necessarily be sacrificed in these cases to speed and convenience. Methods.-Considerable time will be saved in drying if the wet prints are placed on a ferrotype plate, and run thru an ordinary clothes wringer. adjusted a little loosely, to remove the greater part of the superfluous moisture. Blotter M ethod.-One of the most convenient methods where the quantity of work turned out is small is to dry the prints on large "photo finish" lintless blotters. The prints will curl less and collect less dust if they are dried face down. Some surfaces, however, as those of linen and glossy papers, will gather too much lint, even from these blotters, and so must be dried face up. The blotters may be laid aside, several on top of each other, but this piling up materially decreases the rate of dr,Ying. Some varieties of Japanese tissue papers are best dried between blotters under considerable pressure. Blotters are- also available in long rolls. The prints are placed on these face down so that when rolled up, the emulsion is toward the outside of the roll. On drying in this position, the natural tendency to curl inward, is off-set. Cheese cloth racks are better than blotters when the output is large. Cheese cloth or muslin is stretched over large frames and these are arranged to slide in grooves about 6" apart, one above another. The prints are placed on these as on the blotters. An electric fan several feet away will keep the air moving and increase the rate of drying. Ferrotype Plates.-The use of these will be discussed under Commercial Printing (Chapter XVIII). Comrnercial Drying Machines.-These are especially necessary for amateur finishers where hundreds

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or even thousands of prints must be dried daily. A number of first class dryers are available. Some have blotter rolls in W"hich the prints are placed, the rolls then being put into heated compartments. Perhaps . a more common type is one where one or two endless belts slowly convey the prints thru a gas or electrically heated compartment. The prints when emerging are deposited dried, in a suitable receptacle. (Figure 38.)

I I

B y courte::;y of the Pa-ko Co rporu tion.

Figure 38

Co1nmercial Dryer.

It is irnperative that prints be free f rom iniuriou~s chemicals, regardlEss of the method used in drying. Otherwise some impurities will be deposited on the drying surface, causing trouble to later prints.

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FLATTENING.

After prints are dried they are usually found to have a decided curl inward. Some photographer~ straighten them by drawing them, bent sharply with the back down, over a straight edge, as the edge of a table. Use of Flattening Cards.-A much better way is to allow the prints to become nearly dry; then to dampen the backs slightly with a sponge and place between pressing cards in a press or under a heavy weight for two or three hours or until entirely dry. (See Figure 7.) The prints will then remain flat if kept dry. Bristol board or other heavy lintless cardboard may be used for the flattening cards. If llxl4 cards are used, four prints 5x7, two 7xll, or one llxl4 may be placed on each card face down. A similar number may be placed over these, face up, i. e., so that the prints are back to back, and then another card added. In the same way, four 5x7 or 5x8, or two 8xl0 prints may be placed between each pair of 8xl0 cards. Some papers as certain varieties of Japanese tissue may need to be pressed with a hot iron to make them lie flat. Flattening Solutions.-Thin paper will often flatten nicely if soaked for a couple of minutes in a solution of 4 parts of water and 1 part of glycerine and then dried. The following solution will also be found to be decidedly convenient to assure the prints remaining flat: Water (boiling) Nelson's Gelatine Oil of cloves

36 oz. 6 sheets 1 oz.

1 liter. 6 sheets 28 grams

The oil of cloves is added as soon as the gelatine is dis-

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PHOTOGRAPHIC PRINTING

solved and is for the purpose of preserving it. For use, warm slightly and apply a small amount to the back of the prints with a fine grain sponge. The gelatine on drying counteracts the pull of the gelatine coating on the face of the print.

CHAPTER XIV.

TONING. Choice of Colot路.-The color in which the print is rendered should be that which will best interpret the sentiment or feeling which is the motive of the picture. In view work, the warmer tones as sepia are more appropriate for autumn landscapes, while the colder black and white tones better portray the snow and barrenness of a winter scene. In portraiture, the choice lies mainly between black and white, and sepia, with an occasional use of red or green. As a rule, warmer tones are perhaps more suitable for younger subjects than for older ones. Vignetted heads usually look best in black and white. The tendency, however, is to disregard what is most suitable and make the prints in the prevailing "style". For a few years, black and white may be turned out by the best studios. This is perhaps followed by a period of warm blacks and then half a dozen years later only sepias may be considered good. The directions and formulae given in this chapter will enable the photographer to secure almost any tone or color effect in the print which he may desire. The methods outlined are all tried and proven but naturally will not work equally well under all conditions and on all brands of paper. While there are many variations which may be made in each process, 1 only one good method is given under each, the ones chosen being 1

For further discussion, see Photo-Miniature No. 103: Toning Bromide and Gaslight Papers. Fraprie (Ed.): How to Make Prints in Colors.

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reasonably simple and producing prints that are considered permanent. Formulae for specific papers are not included as they can best be obtained from the manufacturers. Nothing is really nicer than good carbon prints (Chapter XX) for securing an unlimited variety of colors, but because of the extra work involved and the greater skill required, they are seldom made in the average studio. Gradation.-Sepia and other prints in color have a shorter scale of gradation as a rule than those in black and white. This is caused to a large extent by the image being more transparent, with the result that the shadows are seldom as deep, and contrast is thereby lessened. Also many of the toning processes tend to have a bleaching action with consequent reduction of the density of the shadow portions. In many cases, sepias are more pleasing than black and white prints for the very reason that the heavy shadows show more detail and have more luminosity. Permanency.-There is a question as to whether the various compounds of silver which compose the majority of toned prints are as stable as the metallic silver of the black and white print. But if the various operations are carefully followed out as described and special attention is given to cleanliness and washing. no fear need be felt but that the prints will last practically as long as any others. Choice of Negatives and Paper.-As just explained, toned prints are usually more transparent and somewhat bleached. This makes desirable the use of slightly contrasty negatives if good results are to be secured. For example, when using a flat negative, by the time the highlights are properly printed and devel-

TONING

15S

oped, the shadows have only a small part of the silver deposit they would have received, if a more contrasty negative had been us.ed. Consequently, the print is flat, and if toned, the silver sulphide will appear yellow rather than a good rich brown. If a flat or short scale negative must be used to produce prints that are to be toned, a rather contrasty or short scale paper should be chosen in order to get a deep deposit of silver in the shadows. Prints for toning should be printed slightly darker than usual. SEPIA TONING.

Sepia methods (Experiment 16) in general change the silver of the black and white print to silver sulphide which. deposited under these conditions, is of a yellowish color. This change may be produced in a number of different ways. the shade and color obtained depending upon the method used. There is of course but one true sepia color but often variations are even more pleasing. Some workers try to produce a certain standard color at all times ; others to secure the most suitable tone for the particular subject. The aim of the conscientious worker should be to learn to produce at all times and under varying conditions the particular tone desired. Hypo Alum Method.-This method is particularly suitable where a large number of prints are to be toned in a short time. While other methods are more rapid for a few prints, this one permits of sepia-toning two or three hundrE:d or more in half an hour. This bath is certain in its action, easily used, and will produce a standard quality of sepia if the black and white prints are uniform and of good quality. It is easily prepared, inexpensive, and may be used over and over many times. It is undoubtedly the most widely used toning method in America.

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PHOTOGRAPHIC PRINTING

Manipulation of Papers.-Printing papers vary between two extremes-those containing only a small excess of bromide or chloride, and those with a much larger amount. The first type under normal conditions of development, with about one drop of saturated solution of potassium bromide per ounce, will produce a slightly cold black and white print, which gives a good sepia. The latter class of papers under the same conditions will give a decidedly olive black and white, and a yellowish sepia. If a medium tone is desired with these papers, it is necessary to use much less restrainÂˇer in the developer in order to produce coarser grained prints of a colder black and white tone. The blue-black print, however, which is very coarse grained, will produce a purple sepia which is as undesirable as the fine grained yellow tone. Contact papers having a finer grained emulsion than enlarging papers should as a rule be toned by this method.

Formula: Water

1 gal. 1 lb. Alum (powdered) 1 lb. Hypo

Water Silver nitrate Sodium chloride (Potassium bromide if desired.)

4. liters .48 kg. 120. g.

B (Ripener) 2 o-z. 60. c.c. 2.5 g. 40 gr. 2.5 g. 40 gr. may be substituted for sodium chloride,

Part (A) is prepared by adding the hypo to the water which is placed over heat. As soon as the hypo is dissolved, add the alum and continue heating, with occasional stirring until sulphurization takes place, i. e., until sulphur is liberated, giving a decided odor. To make sure of more complete sulphurization, it is best to allow the bath to boil for a minute or two. Co1>l the bath to 70Â°F. (21 Â°C.) and add (H), the mixture of silver nitrate and sodium chloride. Then as soon

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as the bath is heated to l10°F. (43°C.), it is ready for use. (See Experiment 6.) Reactions.-The reactions that take place are of interest in that they :make more clear the reasons for the various steps in mixing, as well as the process 1by which prints are toned. A solution of alum in water is weakly acid, and so the aluminUJm salts slowly tend to form aluminum hydroxide and to liberate sulphuric acid. (1) Potassium aluminum sulphate+water=potassium aluminum hydroxy-sulphate+ sulphuric acid. The sulphuric acid then causes the decomposition of the sodium thiosulphate (hypo) with the liberation of sulphur. (2)

Na2 S 2 0 3 + H,S0 4 = Na~S04 + H 2 0 + S0 2 +S sodium sulphuric sodium water sulphur sulphur thiosulphate acid sulphate dioxide

This action is materially hastened by heating which explains why the temperature of the water is brought to the boiling point. The milky color of the bath is caused by the free sulphur which is now in the solution. Any alum remaining as such exerts a beneficial hardening action on the gelatine which otherwise would unduly soften in a hot bath. If the bath were used at this stage, there would be a tendency for the silver to be dissolved, causing the i:mage to be partially bleached. To off-set this, a small amount of silver, usually in the form of silver chloride, is added to the ·bath to ripen it. As silver chloride is easily reduced by the action of light, it is prepared just at the time of using and added immediately to the sepia bath. AgN0 8 + NaCl AgCl + NaN0 3 silver nitrate sodium chloride silver chloride sodium nitrate The silver chloride not being soluble in water is precipitated as a curdy mass and is added in that fonm after the bath is cooled down a little. Caution: If the silver chloride is added to the hot bath, the silver is likely to be precipitated and turn black, making the ripener worthless a~d often causing spots in the emulsion. Instead of adding the ripener, a few old prints or proofs may first be put in the bath, thus furnishing the necessary silver salts. In case the first batch of prints to be toned should be too dark, no ripener would be required as the bleaching action would be beneficial.

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Following Reaction (2) where free sulphur is made available, the silver of the image combines with the sulphur as in (3) to form silver sulphide which in this state is of a yellowish color, toning the print sepia. (3)

2Ag silver

S sulphur

Ag2 S silver sulphide

Procedure.-In order to lessen the danger of overheating and the consequent discoloration of prints, the sepia bath should be placed in an enamel tray which sets in a larger tray containing about an inch of water, thus making a sort of double boiler. A convenient size for the inside tray for a small studio is 16x20". It should be held slightly above the bottom of the larger one by two strips of metal to insure the free circulation of water. Care should be taken that no metallic surface comes in contact with the bath, or the silver may leave the bath and be deposited on it. · The prints need only to be rinsed after fixing before being placed in the hot sepia bath. If the prints have been dried, they should first be soaked in order that the sepia action may start more uniformly. As the action proceeds, the prints should be separated occasionally. This is best done by continually removing the bottom prints and placing them on top. This also lessens the possibility of the lower ones becoming overheated and turning purple. The sepia action is visible first in the highlights, the deeper shadows gradually turning yellow or brown. The process is not complete until all the silver is converted to silver sulphide, or until no black is visible. This will take about 20 minutes if the temperature is kept between 110° and 120°F. (43° and 48°C.). If the bath is used cold, 24 to 48 hours is often required. Many photographers place the prints in the hot bath before leaving for the day, keeping them separated for a minute or two, and then turning out the fire. In

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the morning the prints will usually be finished. Action will only proceed so far in any case, so the length of time has no effect on the shade of the sepia. A warm bath, however, gives a slightly colder. more purple tone; and a cold one by restrained action gives a more yellow tone. A sepia bath may be used over many. times, tending to work faster and give better results after being used for a short time than when freshly made. The amount lost by evaporation and by removal with the prints may be replaced by adding fresh bath without lipener, from time to time. When the bath finally slows down in action and becomes too dirty, it should be discarded. When the action is complete, the prints should be placed on a clean board one end of which may rest in a large tray, and be carefully sponged off with warm water to remove any of the finely divided sulphur. If this is not done, the contraction of the gelatine when the p:ints are placed in cold water will imprison these finely divided particles, giving a whitish appearance to the print. If t oz. of nitric acid is added to 1 qt. (15 c.c. to 1 liter) of the water used for sponging the prints, its efficacy for removing the sulphur is materially increased. The prints are now removed to the wash water and must be thoroly washed as they will contain some hypo if sulphurization has not been completed. Especially in hot weather, when the wash water is warm, some varieties of paper are quitE;! prone to blister and frill after being toned. This condition may be obviated by placing them for five to ten minutes, after sponging and before washing, in a sepia hardener bath made as follows: Water Sodium sulphite Acetic acid Alum (powdered)

5 oz. 1 .oz. 3 oz. 1 oz.

150 30 90 30

c.c. g. c.c. g.

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PHOTOGRAPHIC PRINTING

When these are thoroly mixed, add to 50 oz. water (1! liters). This bath may be used before the sepia bath in case blisters occu1路 during the toning process. It is also desirable for use after the fixing bath for black and white prints in very.warm weather. It may be used over and over many times. Hypo Alum Bath.-(Alternative method). Practically the same rEsults will be obtained路 if the sepia bath is prepared by adding 3 drams of sulphuric acid to 1 gallon (12 c.c. to 4 liters) of freshly made fixing bath. The reaction of the sulphuric acid and hypo as already stated liberates sulphur. The bath is heated almost to boiling to insure more thoro sulphurization, then cooled, and the ripener added as before. When heated to the proper temperature, it is ready for use. Modifications of Hypo Alum Bath.-(a) Gold Tone Papers that contain a considerable excess of brmaidc or chloride salts often give a particularly pleasing ton :J by this method which deposits a small amount of gold in connection with the silver. The regular hyp:> alum bath is mixed as usual, except that boiling water is used to start with. Boiling the bath for two or three minutes is also beneficial. After cooling and adding the rip::ner, heat to working temperature and add 5 grains (.32 grams) of gold chloride. This may be conveniently made up in solution, 1 grain to the ounce, and then the equivalent number of ounces added. Enough basic sodium phosphate or other weak alkali should be added to the bath to produce a slightly alkaline reaction, i. e., so that it will turn red litmus paper blue within one minute. Ammonium hydroxide will answer but its action is soon lost by the evaporation of the ammonia. Borax is often used and works quite satisfactorily. The alkali may be added either before or after the gold chloride and is for the purBaJh.

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pose of bringing about the deposition of the gold more rapidly and in a coarser state, thus giving a colder tone. Prints to be toned in this bath should have the decidedly olive color obtained by using 1! to 2 drops of a saturated solution of potassium bromide to the working ounce of developer. Buff paper is especially suited to this method of toning. After being fixed the prints should be washed sufficiently to remove the acid. In this bath they tone more evenly all over than in the regular hypo alum bath and therefore should be watched carefully and removed when the desired color is reached, or the tone will approximate the ordinary sepia. Too warm a bath gives more of the regular sepia tone; too cold a bath works slowly and accents the gold tone. A good working temperature is from 120° to 130°F. (48° to 54°C.). The bath may be used for some time by the occasional addition of gold chloride solution as necessary in quantities sufficient to continue producing the proper tone. Some photographers prefer the slightly different effect obtained by toning for half the time in • the gold bath and then finishing in the regular hypo alum bath. (b) Warmer Tones.-As a regular hypo alum sepia bath grows older it tends to give tones inclining more toward the purple. This tendency may be counteracted by adding as needed, 15 grains (1 gram) or less of potassium iodide dissolved in a ljttle water. The increased warmth of the tone thus secured is probably due to the restraining action of the potassium iodide. (c) Accelerated Action.-The length of time necessary for toning prints, 20 minutes or longer if the prints are very dark, may be materially reduced by the following method. 2 The prints after being soaked 2

BritiJJh Journal of Photography, March 3, 1922, p. 126.

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PHOTOGRAPHIC PRINTING

for a minute in a saturated solution of hypo are quickly rinsed and transferred to a solution of sulphuric acid, diluted 1 to 12. They should remain there for half a minute, or until the acid penetrates the emulsion, and then be placed directly in the hot sepia bath. The final color is then usually attained in! to 3 minutes路 The more rapid action is explained by the fact that when the prints are transferred from the hypo to the acid, sulphur in a nascent state is precipitated in the emulsion in close proximity to the silver grains. In this state the sulphur is in a superactive condition and on being placed in the hot bath, at once combines with the particles of silver. It is important that the prints be rinsed enough to remove the surface hypo solution before placing in the acid tray or sulphur will soon be precipitated in such quantity as to collect on the prints, forming a yellowish coating which is difficult to remove. Whether the prints are placed in the hypo or the acid tray first, seems to make no special difference. Redevelopment. Method.-This method produces results similar to those obtained by the use of the hypo alum bath, except that the final tone is somewhat warmer. For this reason, it is especially suited to the coarser grained enlarging papers which often become too purple by the methods previously described. Also lantern slides, doretypes, transparencies, and the thinner papers which sometimes will not stand a hot bath, are usually sepia-toned in this way. It has the advantage of ease in preparation as well as in the time of toning a few prints. While not so largely used in this country in studios where considerable work is turned out rapidly, it has met with considerable favor abroad. The only chemicals not already described which

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are used, are potassium ferricyanide and sodium sulphide. Potassium Ferricyanide, K3 Fe(CN) 6 is commonly known as red prussiate of potash. It is formed by the action of chlorine gas on a solution of potassium ferrocyanid::-. In photography it is used in connection with hypo to bleach or dissolve silver images (Farmer's Reducer), and with bromide or chloride salts for redeveloping. Sodiumsulph-ide, Na2 S, occurs in whitetransparent crystals obtained by fusing sodium carbonate with sulphur. It may also be obtained in a fused condition which is considerably stronger than the crystals. It quickly takes up moisture·and therefore should be kept protected from the air or made up into a saturated s::>lution. It oxidizes readily with the result that some hypo may be formed, in which case it would be worthless for redeveloping since reduction would then occur. The small amount of hydrogen sulphide given off accounts for its characteristic odor which is the same as that of rotton eggs. A very small amount of this gas is sufficient to spoil unexposed and undeveloped plates and papers, converting enough of the silver salts hlto sulphides to cause fog and other troubles. So it must not be used or stored in their vicinity. Formula. Two stock solutions should be prepared: Bleacher Water 24 oz. 700 c.c. Potassium ferricyanide 1 oz. 28 g. Potassium bromide 1 oz. 28 g. For use, dilute with equal parts of water. Redet•eloper Water 6 oz. 175 c.c. Sodium sulphide ~ oz. 14 g. For use, take 1 part to 7 parts of water.

Method of Use.-Prints should be of the blue-black type, i. e., not overexposed nor developed with too much bromide as a restrainer. They must be free from hypo

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or they will bleach out in proportion to the amount present and not reappear when placed in the developer. The prints are placed in the bleacher until the image has changed to a pale yellow and no black is visible in the shadows. They have somewhat the appearance of an undeveloped platinum print or a blue print. This action should be complete within one to two minutes. They are then washed in two changes of water and placed in the sulphide solution where the image should return in all its former brilliancy but sepia in color within one-half to two minutes. Washing for half an hour will complete the process. Both solutions should be discarded after using. Iron in contact with the prints or solution during bleaching will often cause blue spots. Reactions.-Redevelopment unlike the direct hypo alum method is an indirect process in that it has to be carried out in two steps. In the bleacher, the potassium ferricyanide reacts with the silver of the image to form potassiUllD ferrocyanide and potassium silver ferrocyanide. Ag2 +2K3 Fe(CN) 6 = K4 Fe(CN) 6 +K 2 Ag2 Fe(CN) 8 This latter compound reacts at Gnce with the silver bromide: K 2 Ag2 Fe(CN) 6 +2KBr = K 4 Fe(CN) 6 +2AgBr The silver bromide image is nearly invisible, being of a pale yellow color. The print is washed to free it from all compounds except the silver 路bromide and then is placed in the redeveloper where sulphur is substituted for bromine as in the following reaction. Na2 S+AgBr = Ag2 S+2NaBr Washing for half an hour should remove the sodium bromide.

Variation and Ejjects.-(1) By first placing the prints for a few minutes in the sodium sulphide bath, washing, and then bleaching and redeveloping in the usual way, a somewhat colder tone is secured. rrhe results which may vary somewhat are likely brought about by a combination of the direct and indirect methods.

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(2) Partially bleaching and then redeveloping will give a colder toned image of silver and silver sulphide. However, prints seldom bleach evenly enough to make this process useful, the result often being that prints are black in the shadows and yellow in the lighter portions. (3) A more satisfaltory method than the one just mentioned, is to bleach the prints completely in the usual bath, wash thru two or three changes of water, partly redevelop in regular metol-hydrochinon or amidol developer, wash, and then finish the redeveloping in the sulphide bath. The image is composed of metallic silver and silver sulphide, the color depending on the relative proportion of each, and that in turn on the amount of development in the regular developer. This method produces good results when colder tones are desired, but of course the uniformity of the prints depends on each being redeveloped in the paper developer to the same extent. ( 4) Bleaching in potassium ferricyanide, potassium bromide, and mercuric chloride will give a wide range of tones from brown to black, depending upon the amount of the mercuric salt present. 3 Adding bichloride of mercury up to 2 grains per ounce ( 4.5 grams per liter) will increase contrast and intensify the print. (CAUTION-Mercuric chloride is a very dangerous poison). Great care must be taken after the prints are bleached, in case the mercuric salt has been added, to wash thoroly, and then to run them thru three weak hydrochloric acid baths, diluted 1 to 70, leaving them two minutes in each bath, and then again washing thoroly before redeveloping, or the mercuric salt may comaFor formulae, see Flint: Chemistry frw Photographers, p. 123. Photo-Miniature No. 103: Toning Bromide an(l

liqht Prints,

G~足

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PHOTOGRAPHIC PRINTING

bine with the gelatine coating. The final image is composed of silver sulphide, mercuric sulphide, and perhaps some mercury. The absolute permanency of the image is somewhat in doubt. (5) Placing prints in a 1% sodium carbonate bath for 10 seconds immediately before redeveloping in the sodium sulphide gives a colder tone. Also, bleaching to silver chloride instead of silver bromide tends to increase the coldness of the tone. 4 (6) The following factors in redeveloping do not appreciably affect the result: (a) Soaking in watet路 before bleaching. (b) Length of time in the bleaching bath. (c) Considerable variation in the proportionate amounts of bromide and ferricyanide in the bath. (d) Length of time in the sulphide bath. (e) Variation from 1% to 30% in the strength of the sulphide bath. Too concentrated a bath, however, is almost certain to cause blisters. Liver of Sulphur Method.-By this method very beautiful sepias are obtained with a minimum of expense and trouble. As the bleaching action is less than by either of the two methods already described, the prints need not be made quite so dark. The principal objection to this method is that all papers do not work equally well, neither do the same brands seem to work the same at all times. Potassium, sulphide (sulphuretted potash, or liver of sulphur) is prepared by heating together sulphur and potassium carbonate in a closed vessel. The resulting compound is variable in composition, likely being composed of a mixture of potassium sulphide and "potassium polysulphide". This accounts for the variability in the action of different samples. It is partially soluble in water. 4 See Communication from Bullock, E. K. Co. Research Laboratorr, in British Journal of Photography, July 291 1921,

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TONING

Formula. This formula 5 has proved very satisfactory in practise. Liver of sulphur Hypo Water

I oz. ! oz. 1 qt.

10 g. 20 g. 1 liter.

The bath should be heated to about 90째F. (32째C.). When the chemicals are dissolved, it is ready for use. Prints are removed when the desired tone is reached and washed for an hour. The slight staining which sometimes occurs disappears during washing. Since toning continues in the wash water, allowance must be made for this factor. The bath should not be used a second time. Another formula which is often used, is similar to the one given but calls for about 20 drops of ammonia to the quart or liter and no hypo. Re-bleaching of Sepia Prints.-Occasionally it is desired to change a sepia print back to black and white. As a sepia print will not bleach in the usual potassium ferricyanide and potassium bromide solution, the following formula has been recommended :6 (A)

Hydrochloric acid Potassium permanganate

(B)

10% solution 5% solution

Mix immediately before using in the following proportion: (A) 2 oz. (B) 1 dram. [60 c.c. of' (A) to 8.8 of (B)]. It may be used full strength as indicated when there is difficulty in getting the prints to bleach, but for general use it is diluted 1 to 1, or 1 to 2. After bleaching, the print is washed and redeveloped in amidol or other regular paper developer. Or if it is desired to tone it sepia again, the regular sulphide bath may be used. 5

This formula is patented by Fenske.

British Journal of Photography, June 10, 1921,

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PHOTOGRAPHIC PRINTING

Factors Affecting Warmth of Sepia Tones.-(See Experiment 15.) The causes of variation in the color of sepia prints are summarized below for convenience in reference. Naturally most of the factors are opposites. Factors Tending to Ca:use Cold Tones Papers containing minimum of excess bromide. Matte and rough papers. Enlarging papers. MinLmum amount of potassium bromide in developer. Increase of sodium sulphite in developer. Amidol developer. UnderelCposure and forced development.

Hypo alum method. Hot hypo alum sepia bath. Addition of gold chloride and possibly excess silver nitrate to hypo alum bath. Old sepia bath, containing considerable silver salts. Sulphiding before normal bleaching in redeveloping. Bath of 1% sodium carbonate solution before sulphide bath. Bleacher containing mercuric chloride. Bleaching to silver chloride instead of silver bromide.

Factors Tending to Cause Warm Tones. Papers containing considerable excess of bromide salts. Smooth papers. Contact printing papers. Considerable potassium bromide in developer.

Overexposure and underdevelopment. Cold developer with probable consequent overexposure. Redevelopment method. Cold hypo alum sepia bath. Addition of potassium iodide to hypo alum bath.

OTHER TONING METHODS.

A great many formulae have been suggested from

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TONING

time to time to secure various tones other than sepia. To avoid confusion, only one of each type is given. The use of dyes is not to be recommended because of their tendency to stain the highlights excessively. Chalk Red Tones.-While not desirable for the usual portrait work, this tone is very suitable for firelight effects. Prints to be toned by the following formula should be a good sepia, fully developed and well washed. If any hypo is present, it may precipitate the gold and stop the toning. A

Water Gold chloride

15 oz. 15 gr.

450 c.c.

15 oz. 90 gr.

450 c.c. 6 g.

1 g.

Water Potassium sulphocyanate

Using equal parts, slowly add either solution to the other while stirring to prevent the precipitation of gold. The solution which is now of a brick-red color should stand for a few minutes until it clears. Prints should tone to a chalk-red color in about 15 minutes and should then be fixed in the regular acid fixing bath and washed as usual. The color of the prints depends upon the amount and state of division of the gold deposited. If prints are removed from the bath after a short immersion just after action has been started, they will be a beautiful tone, neither sepia nor red. The quantity given should fully tone five dozen 4x6 average pt路ints. It may also be used with equal success in toning lantern slides and other .glass positives. Blue Tones are most effective for snow and moonlight scenes, views of water, etc., and may be secured either on prints or on glass positives. They are not

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PHOTOGRAPHIC PRINTING

suited to tinted borders and vignettes or other prints having large expanses of white. Prints should be a good black and white, fully developed, but perhaps a trifle light, and free from hypo. A

Water Potassium ferricyanide B Water Ferric chloride

1 qt. 30 gr.

1 liter 2 g.

1 qt. 30 gr.

1 liter 2 g.

When these chemicals are thoroly dissolved, add (B) to (A) slowly while stirring. Then add Nitric acid

2 oz.

60 c.c.

Prints will tone in a few minutes and when the desired depth is reached should be removed to a tray of water and washed thoroly to remove the toning chemicals. The silver image is probably converted to potassium ferrocyanide and this to Prussian blue. In addition to the toning action, considerable blue stain is produced, which if objectionable, can be largely removed by washing. After washing, the prints should be carefully blotted to remove surface moisture which otherwise might collect in drops, causing a deeper stain at those places, on drying. The hands and trays will be stained when using the blue toning bath but may easily be cleansed by washing in a solution of sodium carbonate. Green Tones are especially suitable for views and unconventional outdoor portraiture. Methods of green toning are somewhat less certain in their action and permanent in results than the ones already described. Papers are available which develop to a good green by the usual process and are much to be preferred to toning methods. However, the followinA green-toning

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TONING

formula is recommended by the Ansco Company7 and has been used by the writer with considerable success. A Potassium ferricyanide Ammonia Water B Ferric ammonium citrate Hydrochloric acid Water

33 gr. 80 minims 3~ oz.

2 g. 5 c.c. 100 c.c.

Sodium sulphide Hydrochloric acid Water

1M gr. 80 minims 3~ oz.

1 g. 5 c.c. 100 c.c.

77 gr. 5 drops 3l oz.

5 g. 5 drops 100 c.c.

The black and white print after being fixed and washed, is placed in Solution (A) two or three minutes or until bleached to a light brown. 1t must then be thoroly washed again and placed in Solution (B) for five minutes; then rinsed and transferred to Solution (C) for five minutes; then washed for half an hour. In Solutions (A) and (B), the print takes on a blue color which in combination with the yellow sulphide color of (C) forms a green. Combination Toning.-For details in regard to combination toning and the various effects which can be obtained, the student is referred to the book mentioned earlier in the chapter: How to Make Prints in Colors. The majority of such methods are hardly practical for general studio use. 1Po1路trait, November 1920.

CHAPrER XV.

DEFECfS IN PRINTS. It may be well at this point,~after the prints have been developed, fixed, perhaps toned, then washed, dried, and pressed,-to pause and consider wherein they may be defective. Many factors may have arisen to impair the work from the technical as well as the artistic side. The imperfections may have been caused from impure chemicals, wrong methods of mixing, or improper methods of manipulation. While somewhat in the nature of a review this survey should be well worth while, for the more important defects found in prints are classified and discussed here at greater length than was possible at the time of their occurrence. There are so many faults that may appear that not only the beginner but often the more advanced worker is at a loss to know just where the trouble lies and how to remedy it. An effort has been made to group these defects so as to make the table most convenient in locating trouble. 1. Abrasion marks. 2. Blisters, caused by (a) Change from alkaline to acid baths, (ib) Defective fixing bath, (c) Sudden change in temperature, (d) Air in the water, (e) Alkaline 路wash water, (f) Mechanical causes, (1) Creases, folds in paper. (2) Spray of water. (g) Sepia causes, (1) Too hot sepia bath. (2) Too strong sulphide bath.

DEFECTS IN PRINTS 3. Color, unsatisfactory. (a) Blue-black. ('b) Olive. (c) Purple and yellow sepias. 4. Contra;.t, excessive. 5. Dark prints. 6. Deposits. (a) White scum. (,b) White powder or crystals. (c) Yellow deposit. 7. Fading tendency, caused by (a) Dampness, (b) Incomplete fixation, (c) Insufficient washing, (d) Light action. 8. Fllatness. 9. Fog, caused by (a) Chemical action, (1) Old paper. (2) Fumes. (3) Action of reducing agents. (4) Improper mixing of developer. (.b) Light action, (c) Use of fogged negatives. 10. Mottled appearance. (a) Temporary. b) Permanent. 11. Muddy appearance. 12. Spots. (a) Black. (路b) Blue-'black. (c) Purple. (d) White. 13. Stains. (a) Pink. (b) Red or brownish. (c) Yellow. ( 1) Silver stains. (2) Oxidation stains. 14. Uneven development. 15. Weak prints. ( 1

171

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PHOTOGRAPHIC PRINTING

1. Abt路asion Marks (sometimes known as stress or pressure marks). These are usually in the form of fine lines or streaks across the paper. While more often occurring on glossy papers, they may occasionally be found on the dead matte surfaces. If pressure has been brought to bear on a sensitive emulsion at any point, that part, on development, will often show a denser deposit of silver. Papers which show these markings have in all probability been subjected to stress at some time, causing an abrasion on the surface. This may have occurred in the process of manufacture, shipping, or after the photographer has received them. A slight rubbing together of the paper in the package is one of the most usual causes. A small amount of potassium iodide added to the developer, making a so-called "non abrasion" developer, will usually cause sufficient restraining action to prevent the occurrence of these markings. Too much iodide, however, will cause flatness and a general dingy appearance. About ! grain to the working ounce (.025 gram per 100 c.c.) should be sufficient, less being used where possible. Rubbing the finished print with a chamois skin or cotton moistened with alcohol will often remove the marks. If not, then the use of the cyanide-iodide re-. ducer, described in Chapter XVIII, considerably diluted, will be positive in action.

2. Blisters.-There are a variety of causes which combine to produce blisters and frilling. Sometimes the emulsion is not sufficiently adherent in spots, and then it is likely to blister under any of 'the conditions described below. The underlying cause may occur at any time in the making of the prints, but usually blisters first show up during washing. They most often occur on glossy papers. (a) Change from Alkaline to Acid Baths.-This

DEFECTS IN PRINTS

173

is one of the fundamental and most prolific causes of blisters. An ideal condition for their formation would be to transfer prints from a developing bath, strongly alkaline, to a short stop or fixing bath containing an excess of acid. The acetic acid of the latter baths reacts with the sodium carbonate of the developer in the emulsion to form sodium acetate, water, and carbon dioxide gas. If, because of too strong acid, the gas forms more rapidly than it can escape, it will create pressure tending to raise the gelatine. This pressure may not be sufficient to cause the appearance of blisters at the time, but later in manipulation, when other causes have softened or cracked the emulsion, they are likely to occur. (b) Defective Fixing Bath.-Not only may the fixing bath be too acid but it may cause trouble by becoming too alkaline. When no short stop is used, the acid of the bath is neutralized by the sodium carbonate of the developer which is carried over by the prints. This alkaline bath has a sofitening action on the gelatine and so produces a favorable condition for blisters. A weak or worn out fixing bath is, however, perhaps the most important cause. A bath in this condition unfavorably affects the prints in two ways: (1) The hardening action is absent or lessened to such an extent that the print is more susceptible to all the other causes. (2) The print is soaked full of fixing bath which now contains not only hypo, acetic acid, sodium sulphite, and alum, but also more or less of the oxidation and reduction products of the. developer and of the print, as well as the products of reaction between the hypo and the silver salts of the paper. All this makes up a dense, non-hardening solution. When the print is transferred from this fixing bath to clear water, an interchange of the water and the denser solution in the print takes place thru the cells of the emuls~on. This process, known as osmosis, may be stated

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PHOTOGRAPHIC PRINTING

as follows: When two liquids of different densities are separated by a porous membrane, the liquids will flow thru and mingle, and the greater flow is from the less to the more dense liquid. In the case of the prints, the greater flow is from the clear water to 'the denser chemical mixture which is in the print. The excess pressure so caused, is often sufficient to cause the gelatine to raise in the form of blisters containing a liquid instead of a gas as mentioned in other cases. If a fresh fixing bath had been used, the difference in the density between the bath and the wash water would be less and this trouble probably avoided. (c) A Sudden Change of Temperature is the third and last of the most important causes. This may happen between any two solutions as developer to short stop, shor't stop to fixing bath, fixing bath to sepia bath or wash water, or in washing, from one wash water to the next. Naturally, in winter, when luke-warm water is likely to be used for convenience in handling, considerable variation may occur from one tray to the next. The sudden change in temperature contracts or expands the gelatine, but blisters are not so likely to be produced unless air or gas is imprisoned in the emulsion as already mentioned. The safe rule is to avoid sudden changes of temperature and to see that the fixing bath contains suitable hardener. (d) Air in the Water.-If the walter contains a large amount of dissolved air, it penetrates the emulsion along with the water. Any sudden increase in temperature causes expansion of the air which in its attempt to escape may raise the gelatine with the formation of blisters. Water under high pressure is most likely to contain considerable air. If allowed to stand in an open vessel for a time the air will escape. Proper hardening of the emulsion will also help prevent this trouble,

DEFECTS IN PRINTS

175

(e) Alkaline Wash Water.-This may tend to soften the gelatine and to that extent increases the probability of blisters. (f) Mechanical Causes.-Creases and folds in the paper are liable to cause a weakening of the emulsion at these points. So would a heavy stream of water striking the prints. These conditions would make easier the formation of blisters from some of the other causes. (g) Sepia Causes.-A very hot sepia bath or too strong a sulphide bath is almost certain to form blisters on some papers. Drying 'the prints or placing them in a hardening bath previous to these operations is helpful. Removal of Blisters.-After blisters are once formed, there seems to be no certain remedy. If small and not too numerous, the paper underneath may be pricked with a pin and the air or water pressed out. Occasionally, placing the priJllts in a hardening bath such as is recommended for use after toning, will prove efficacious, but the blisters tend to reappear when the prints are being washed. Another method is to immerse the prints in a dilute alcohol solution, then in a stronger solution, and then in full strength alcohol. Washing is not then necessary. 3. Unsatisfactory Color.-(a) A blue-black color is caused primarily by using too small a quantity of potassium bromide in the developer. Underexposure and forcing in development will increase this tendency. (b) Conversely, an olive tone is caused by an excessive amount of bromide, perhaps along with overexposure r . and underdevelopment. (c) The factors affecting sepia color, 路giving purple and yellowish tones, have been discussed in Chapter XIV on Toning and need not be repeated here. 4. Excessive Cont:rast.-By this is meant that

176

PHOTOGRAPHIC PRINTING

there is too great a difference between the highlights and shadows. The highlights are chalky and detail is lacking, while the shadows are so dark that the tones run 'together, obliterating detail there as well. Naturally this result is caused, in the main, by using too short a scale (too contrasty) paper for the negative so that if the highlights are correctly printed, the shadows are too deep, and vice versa. Underexposure and the use of too contrasty a developer may be contributing causes. 5. Dark Prints.-:-These are caused by overexposure or overdevelopment or both. 6. Deposits.-(a) Of the different kinds of deposits which occur on prints, white scum is most often found. If caused by sediment from the wash water, it may be overcome by carefully wiping off the prints with damp cotton, when removing from the water. The white deposit often seen on prints that have been sepia-toned is caused by the finely divided particles of sulphur and other sepia bath chemicals becoming imbedded in the gelatine when the prints are transferred to the hardener or cold water. Rubbing the prints off with warm water after removing from the sepia bath will usually prevent the trouble. If not, then immerse in a bath of nitric acid and water (1 to 60 solution) for a few minutes after the prints are sponged off, before washing. (b) A deposit of white powder or crystals is usually formed on prints that have been insufficiently washed, by the hypo crystallizing out on the surface. If hypo is present in large quantities, this action may occur within a few hours. while with a lesser amount, it may not be noticeable for some time. If the deposit is not soluble in water but is in sodium carbonate or acetic p.cid, then. it consists of a.lumin.um sulphite resultin~

DEFECTS IN PRINTS

177

from the use of an old fixing bath which has lost most of its acidity. (c) A yellow deposit may be found if the hypo crystals have in any way become broken up with the liberation of sulphur. This action may not take place until years after the print is made. Instead of trying to save the print, it is better to copy it with a 'yellow filter on a color-sensitive plate or film, and then to make a new print. 7. Fading.-(a) Black and white prints, even more than sepia prints, are very liable to fade if exposed to excessive moisture. This trouble may be largely avoided by mounting the prints solid with the aid of dry mounting tissue. The shellac tissue will prevent moisture entering from the mount. The prints may also be varnished with any good photo water-proof varnish. (b) Incomplete removal of the sensitive silver salts by the action of the hypo will result sooner or later in the fading of the print. (See pink stains.) (c) Insufficient washing will leave hypo and other chemicals remaining in the emulsion. Sulphurization takes place, and the print gradually fades. (d) Strong light as direct sunlight may in time cause prints to fade to a greater or less extent. 8. Flatness is usually the result of using too soft (too long a scale) paper for the negative. Overexposure and underdevelopment, and the use of a soft developer help to increase the trouble. If the highlights are correctly exposed, then the shadows are gray and not a good rich black. If the shadows are properly printed, then the highlights are overexposed, and show considerable deposit. 9. Fog.-By this is meant the reduction of the silver salts on the paper, causing a silver deposit or

178

PHOTOGRAPHIC PRINTING

gray tint where there should be none. (a) Chemical fog 1 is produced by a variety. of causes. The printing paper becomes more or less fogged if kept too long, especially in a warm, damp place. If stored in a room where redeveloping is carried on, the sulphide fumes (hydrogen sulphide gas) are very liable to enter the packages thru small crevices, causing fog, streaks, markjngs, etc. (See Experiment 24.) Too large a proportion of any of the agents making up the developer may also cause a chemical fog known as "developer fog". The maximum amount that any of the ingredients may be increased, can best be determined by trial. Especial care must be taken not to increase the sodium carbonate too much when making up a faster and more contrasty developer. If the developer is improperly mixed, e. g., if the carbonate is added after the metol without the protective action of th~ sulphite, considerable oxidation products will be formed, which tend to cause fog. As heat hastens oxidation, the fogging tendency will be increased by the use of too hot water when preparing it, or if the de-veloper is too warm when using. Prolonged development of underexposed prints will result finally in the reduction of the unexposed silver salts and so cause fog. Developing chemicals sometimes contain impurities as sulphates, metallic sulphides, and salts of tin and copper, any of which will decidedly increase the fogging tendency of the developer. (b) Light Fog.-Exposure of paper to an unsafe light will start the reduction of some of the silver salts, resulting in a gray deposit which shows up in the highlights. A light may be considered safe if a minute's expOilure of dry paper at a distance of two feet from it produces no visible fog. (c) Use of Fogged Negatives.-Naturally, using . tCrabtree: Chemical Fog (Amel'ican Annual of Photography, 1919).

DEFECTS IN PRINTS

179

a negative that is fogged will result in a fogged appearance of the print. In this case, a slight reduction of the negative with a cutting reducer should prove beneficial. Prevention.-The addition of potassium bromide to the developer acts as a preventative in the production of fog. It seems to do this by diminishing the solubility of the silver salts. Potassium iodide added to the developer converts some of the silver chloride or bromide to silver iodide which develops with difficulty and consequently has less tendency to fog. 10. Mottled Appearance.-(a) Prints when wet often present an extremely mottled appearance, especially by transmitted light. This is caused by the paper support not absorbing water uniformly. The condition is temporary and disappears on drying. (b) Pennanent.-ln a warm humid atmosphere, prints may take up considerable moisture in spots before printing or between printing and developing, if they are allowed to lie for a few hours. (See Experiment 23.) This appearance often remains after drying. A permanent mottled effect is also caused on many papers by underdevelopment. Prints that have been overexposed also come up mottled in the developer. This condition would disappear on full development, but by that time the prints would be far too dark. 11. Muddy Appearance--Overexposure and the use of insufficient restrainer are two of the main causes of the smudgy appearance seen in many prints, especially in the shadows. Exposure of the paper to dampness and chemical fumes as well as the use of too soft paper will tend to produce similar results. 12. Spots.-(a) Small black spots are caused by the prints not being fully and evenly immersed in the

180

PHOTOGRAPHIC PRINTING

short stop or fixing bath. Air bubbles permit the developing action to continue further at .those points. The spots may also be caused by particles of rnetol, pyro, etc.. falling on the emulsion before development. (b) Blue-black spots are produced by iron in the water. They are most often formed during bleaching before redevelopment, by specks of iron, perhaps iron rust that has collected on the print, combining with the potassium ferricyanide to form an insoluble blue cornpound as in blue-toning. (c) Purple spots are formed by excessive heat in the sepia bath when bubbles of air remain in contact with the gelatine surface of the print. Also, if a print lies face down on the bottom of the sepia pan for some little time, the high temperature often cooks the emulsion, causing it to turn purple in spots. (d) White spots· are formed when by improper immersion of the print in the developer, air bubbles prevent the solution from reaching the emulsion for a time, with consequent underdevelopment at those places. Particles of hypo dust, or small drops of hypo or acetic acid falling on the emulsion before development, will also produce white spots. 13. Stains.-(a) Pink stains are the result of incomplete fixation, whether due to too short immersion or to the use of a weak or worn out bath. The unexposed and undeveloped silver salts that should have been removed by the hypo bath remain to be gradually affected by the lhrht, turning pink and then dark. (b) A red or brou•nish r"olor when the print comes up in the developer indicates either that the rnetol has been omitted or that the developer is nearing exhaustion. (c) Yellow sfa.ins areoftwotypes: sDverstains and oxidation stains. Silrer stains may be local or extend uniformly over the entire print and are produced by a

DEFECTS IN PRINTS

181

variety of causes. In the chapter on Fixation, mention was made of the fact that in fixing, a relatively insoluble compound of silver sodium thiosulphate is formed before the soluble double thiosulphate. If the prints are removed from the hypo before the change is complete, washing is not likely to remove all the thiosulphate. Also, if the prints are not fully immersed in the fixing bath or if they remain in contact with each other in that solution, fixation will not be complete and the same result will occur. In time this silver compound is likely to be changed, by the action of small amounts of hydrogen sulphide in the air, into silver sulphide, giving a yellow color. An old or exhausted fixing bath is not only liable to produce the same effects, but it also contains considerable excess silver in solution. Some of this may remain in the print and on exposure to the air, gradually be turned into silver sulphide. Silver stains are difficult to remove. A weak cyanide-iodide solution, as described in Chapter XVIII, will usually dissolve the objectionable compound, but at the same time it will reduce the silver image. In the case of obstinate stains in old prints, copy the print, using a panchromatic film or plate, and a yellow filter. Oxidation stains are also produced in several ways. They are caused by the oxidation and consequent discoloration of the developer which of course stains the prints. If the stain is somewhat uniform over the print, it likely has been caused by using an old oxidized developer or an exhausted one. If prints are underexposed and require forcing, stain is quite likely to be produced, especially if the developer is warm. Holding the prints up too long for inspection or when locally developing, will give the thin film of developer clinging to the paper, time to become oxidized and this will produce a yellowish or brownish stain. If the stain only shows in spots, it has likely been produced by in-

182

PHOTOGRAPHIC PRINTING

complete immersion in the developer. If part of the print. as a corner, remains above the surface for several seconds, oxidation takes place, causing discoloration in that part. Yellow oxidation stains may often be traced to hypo in the developer, and they may also be produced in the fixing bath. If no short stop is used, the acid of the fixing bath gradually becomes neutralized by the sodium carbonate of the developer. When this condition is reached, the film of developer left on the prints oxidizes more readily in the fixing bath. Excess developer should be drained from the prints which should first be put into an acid short stop bath. If the fixing bath is frothy when shaken, it is probably alkaline and should be discarded. Oxidation stains can be removed by bleaching the prints in the following solution: Hydrochloric acid (10% solution) 4 oz. Potassium permanganate (5% solution) ~ oz. Water 12 oz.

125 c.c. 8 c.c. 375 c.c.

Mix just before using. The hydrochloric and permanganate solutions may be kept for an indefinite time, separately. If prints show a decided brown stain after being bleached, place in a 1% sodium bisulphite solution for a few seconds. Rinse after bleaching, and develop in strong daylight in any good paper developer. The following alternative bleaching formula is recommended2 as being of more uniform strength: A

Potassium permanganate Water to

gr. oz.

5 g. 1 liter.

2i oz. ~ oz. 32 oz.

75 g. 15 c.c. 1 liter.

75 32

Sodium chloride Sulphuric acid (concentrated) Water to

2Crabtree: Stains on Negatives and Prints Annual of Photography, 1921).

(American

DEFECTS IN PRINTS

183

The reaction between the sulphuric acid and the sodium ch!oride produces hydrochloric acid. The method of use is the same. The various pink and yellow stains when first appearing may be disposed of, if not too bad, by another method. Place in a fresh fixing bath to make sure that fixation is co;nplete. Then tone in the usual hypo alum bath. The stain is usually made invisible but there is a chance that further changes may take place in the print that will result in fading or other troubles. 14. Uneven Development.-This may be the result of several things: damp printing paper, touching the paper with damp fingers, the use of improperly compounded developer, uneven immersion in the developer, or overexposure with too little bromide in the developer. 15. Weak Prints are caused either by underexposure or by being bleached. The latter action may be due to using too strong a hypo bath, by leaving the prints too long in the fixing bath, or by using a hypo alum sepia bath that has not been ripened either by the addition of silver nitrate and potassium bromide. or by first toning some old prints or proofs.

CHAPTER XVI. FINISHING. After prints have been dried and flattened, they need still further attention before they may be considered finished in a way pleasing to those who admire good pictures. The following steps are yet necessary and should be carried out in the order given: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Selection of mounts (unless to be framed). Trimming. Plate-sinking. Embossing (if needed). Mounting (if not to be framed). Cleaning. Spotting. Air brushing (if needed). Sketching (if desired). Coloring (if desired). Framing (if to be so finished). Miscellaneous.

Selection of Mounts.-This is necessarily the first step as otherwise the size to which the print is to be trimmed is not known. To the novice, mounting may seem the very simple procedure of fastening a print to a gray or brown piece of cardboard. Those who have had wider experience realize that considerable technical and artistic ability is necessary if the result is to be other than mediocre. The function of the mount is to separate the路picture from its surroundings and form a suitable and harmonious background that will set it off to the best advantage. It must not compete with the picture in interest but should form a window thru which the object of interest is seen. Each of two mounts may har-

FINISHING

185

monize equally well with the print but one may destroy the effect in mind, whereas the second may contribute favorably to the impression the picture attempts to convey. (Note: The terms mount and folder are used interchangeably in this chapter. Strictly s~aking, however, the so-called "flat mounts" are generally used for commercial work, and for portraits that are to be framed or hung in exhibitions, while most studio portraiture is placed in "folders"). Color.-The color of the mount must be in harmony with the tone of the print. (a) Seldom will a gray mount be suitable for a sepia print, or will a brown print look well in a cold-tone gray folder. Sepia and warm black prints, however, often show off to good advantage in buff or cream tinted folders. While both cold and warm tones are sometimes combined in one mount and may be used either for gray or brown prints, this type seldom showsâ&#x20AC;˘ off either kind of picture at its best. Neither are mounts of neutral type very satisfactory for use in this way but they are very appropriate for much of the colored or tinted work. (b) Either a light or a dark print is wonderfully improved by using a folder or mount of suitable depth of tone. A mount lighter than the picture makes it appear darker while similarly a darker mounting will have the effect of making the print seem lighter. Therefore, if a picture has been finished too dark, select a still .darker mount; if too light, an even lighter one. In general, the immediate margin around the print should be lighter than the deepest shadows and darker than the highest lights. (c) If a print is rather flat, strong contrasts in the mount should be avoided. A picture in a delicate gray, slightly softened by diffusion, requires a light or cream tinted folder of soft flexible material with

186

PHOTOGRAPHIC PRINTING

roughly finished edges. A strong contrasty print, however. may be placed either in a white folder, or a very dark one, or one combining the two qualities. (d) Prints that are unsatisfactory in color may be improved by choosing a suitably contrasting tone in the mount. If a print is a "foxy" yellow, this color would be rendered all the more conspicuous by being placed in a folder of deep Vandyke brown. Instead, a pale yellow-brown, cream, or buff folder should be chosen. Rich brown prints, however, may also look well in cream folders. A brown, too near the color of the shadows, should be avoided. If a rusty black and white print is placed in a brown instead of a gray folder, the effect of the contrast will be to make the black seem colder in tone, while a cold-gray mount would make the same print appear even more rusty. Size.-To find the size folder or mount in which the picture will appear at its best, make use of a pair "'f L-shaped masks or squares. Lay them over the print and move so as to secure openings of various sizes and p:路oportions. In this way it can be determined what size opening the folder should have in order to get the best arrangement and composition in the print. The earnest worker who wishes to get the best results should secure and study good books on composition, perspective, harmony, and allied subjects. 1 The smaller the print, the greater the proportion in the mount it will stand. For example, a 4x6 print may look well in an 8xl2 folder, but a 12x18 print would be lost on a 24x36 mount, altho the proportions are the same. Kind of Mounts.-A few photographers who have a well developed artistic sense prefer to make their own folders and mounts so that these will best suit the intSee Burnet: E:ssays on Art. Pictorialists of Buffalo: Pictorial Landscape Photography (p. 147).

• • •

•

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FINISHING

dividual picture. But the manufacturers of photo.. graphic mountings have accomplished such wonders in recent years in providing an almost unlimited variety of artistic folders, that most photographers may well question the advisibility of making up folders themselves unless it be for exhibition or other displays .

•

• •

•

Figure 39

•

Types of Folders.

Folders are of four general types: (1) The artist proof case or folder made from one piece of material so folded that only top and bottom flaps hold the print in place (Figure d). This style is most suitable for vignettes, tinted borders, and other prints having a considerable expanse of plain color. (2) Corner pocket

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folders are those where only the corners of the print are held in place under small portions of the folder (Figure a). The print may extend to the edge of the mounting surface of the folder. or the corners under which it slips may be some distance from the margin, thus allowing for a border. All kinds of pictures may be mounted in this way, altho tinted borders and vignettes are especially suited. (3) Slip-under folders, where the print is fastened in place underneath an insert with an opening the desired size (Figure c). This type is perhaps best for the greater proportion of studio work. (4) Tip-on folders, in which only the upper corners of the print are fastened, are used especially for prints of an artistic nature (Figure b). Many photographers, for their high class work, simply insert the prints, made on heavy-weight paper, into a book-folder the same size as the print. In this case, the folder serves primarily as a protection, the photographs themselves being of such artistic merit that they do not need an insert in the folder to provide them a setting. Shape of Mounts.-Curved lines lend grace to a subject and so folders with oval openings are often preferred for pictures of women and children, where beauty of line and form is the aim. Straight lines on the other hand seem to give support and stability, so mounts with a rectangular opening are in most cases better for men, this shape giving an impression of strength and dignity. The square opening and the circle are not so good and are seldom used. 2. Trimming.-Several things should be kept in mind when trimming prints. (a) Trimming is for the purpose of removing any portions which might detract from the principal object of interest in the picture. Anything that does not help center this interest is harmful and shouldbe eliminated. (b) Again, the gen-

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eral composition is often improved by judicious trimming. The shape and proportion of the print must depend largely on the subject matter it contains. A general landscape might appear well in a long panaromic picture, but such proportions would be entirely out of place in showing the height and beauty of a clump of tall pines. (c) Vertical and horizintal lines that are not true should be corrected wherever possible. A portrait with the vertical lines of the background not parallel with the sides of the print is only less objectionable than an ocean view with the skyline at an angle with the base of the picture. Of equal importance with these is the necessity of getting a good clean-cut edge and using a folder that is of proper size to fit the trimmed print. A number of satisfactory trimming boards are available, ruled off in squares, and fitted with rule or gage, and cutting knife. 3. Plate-Sinking.-Small pictures are often printed on larger sheets of paper leaving a white margin. When this is done, as in the case of a 4x6 print on 7xll paper, the effect is heightened by "sinking" the print with a small border around it. If this is to be done, care should be taken when making the print that the opening in路 the mask thru which the picture is printed is properly spaced. For the size mentioned, both the top and side margins might well be 1!" with the bottom 2!". Vertical prints should have the top margin equal to or slightly greater than the sides but never as wide as the bottom. Otherwise the print appears to be top-heavy. Horizontal pictures sometimes look best with the top margin slightly narrower than the sides. The materials needed for plate-sinking are only an embossing tool, a sheet of heavy-weight paper or ground celluloid, a damp sponge, and a light source

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.such as the top of a printing machine. An ordinary bone knitting needle or crochet hook, sandpapered down to a slightly rounded point makes a fine embossing tool (Figure 40B). Method. Cut a plain piece of double-weight printing paper or similar material to a size i " wider and 1" longer than the picture on the print. Dampen the

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Figure 40

Finishing Tools.

print very slightly for an inch around the picture to prevent the cracking of the emulsion. Place the rectangular form on the top of the printing machine, laying the print over it, face down. When the lights are turned on, the size of the picture is easily visible thru the paper. Adjust the print so that the form shows an even margin at the top and sides. This will be j-", leaving the botton margin j-". Press the rounded point

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of 路the embossing tool on the back of the print along the edge of tlie card underneath, carefully following around it. This will make what looks like an indented line in the back, but when the print is turned over. it is seen that a very pleasing sunk-center effect has been produced. If the print has been dampened too much, it may cockle when drying; if too little, or if the form used is too thick, the emulsion may be cracked. Sizes.-6x9, 7x10!, 8x12, 9x13, llx14t are examples of good proportions in pictures to be printed on larger sheets. The last could well be used on a sheet 14x19!, giving a margin of 2" at the sides and top, with 3" at the bottom. Panel pictures are especially effective with sunk centers. Ovals may have either an oval or square border. The plate-sunk edge is usually from h" to G" from the edge of the picture at the sides and top, with a slightly greater margin at the bottom. 4~ Embossing.-Prints with white margins as vignettes and tinted borders, and those with sunk centers may be made more attractive by having the edges embossed. This is done in a manner similar to platesinking except that in this case, the surface is raised. Simply dampen the print along the edges and place face down on an embossing board (Figure 400). with the margin projecting over one of the grooves. With the roller, the edge is pressed down into the groove, giving the effect shown in Figure 22. An alternative method, giving perhaps a neater raised edge, is more on the order of plate-sinking. Lay a piec~ of double-weight printing paper slightly longer than the print on top of the printing machine. Over this, place the print face down so that one edge projects about an eighth of an inch. With the tool used for plate-sinking, firmly press the print down over the edge of the card underneath. Repeat on all sides if desired.

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If prints are to be placed in slip-under folders, embossing is useless since it would be covered up. Neither is it necessary on the ends of prints to be placed in artist proof folders. Dark borders are seldom improved by embossing. 5. Mounting is largely a matter of neatness and good taste. An ordinary print, carefully mounted with attention to spacing, harmony, and tonal values, is much more effective than a print reflecting high artistic ability in lighting and posing, but carelessly mounted. Most portrait work is mounted in folders. If of the slip-under variety,Âˇ it is only necessary to get proper spacing and then to run a line of glue around under the insert flap of the folder, with a fine line also under the upper end of the print to prevent slipping. The folder is then closed and placed under a light pressure for a time until the glue hardens. Care must be taken that there are no drops of glue under the print except where covered by the folder, or unsightly raised portions are likely to be the result. A most convenient method of putting glue along the ends of the backs of prints is to lay a dozen or whatÂŁver number are ready to mount, face down on the table so that each projects about a quarter of an inch beyond the one above. A fine line of glue from a tube (glue pencil) can be run along the projecting edges of all the prints in a few sÂŁconds. Prints in artist proof cases should be glued at each end to prevent buckling and to insure their staying in position. Prints in corner folders should be fastened under each corner. There is a growing tendency to flat-mount portraits with dry mounting-tissue, even in folders, thus largely removing the uncertainty as to whether they will remain properly mounted. This method is used extensively for commercial work, the term commercial

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being used to include all pictures that are not portraits. Prepared mountants as glue and mounting tissue are so convenient that they have largely taken the place of home-made flour paste arid similar adhesives. 6. Cleaning.-After the prints are mounted, there is no further need of touching them with the fingers. Prints with light borders, however. may already have become soiled, especially if handled to any extent. Most kinds of dirt may readily be removed by rubbing with a piece of Artgum or even better with a kneaded rubber eraser, which being softer, is less likely to mar the print. Some papers with a sheen, however, will show the streaks caused by cleaning with erasers. So if dirty, these had better be rubbed with cotton dampened with alcohol. Oxgall is also used for cleaning, especially before coloring. Fine pumice powder is very good for obstinate cases of dirt. 7. Spotting.-The necessity for spotting results almost entirely from careless manipulation somewhere from the exposure of the plate to the present stage: Dust on the plate in the camera, and dirt on the negative or printing machine top is the cause of most路 of the white or light spots. If these and similar defects are not removed, the print can not be considered finished. The necessary materials for spotting are few: a good No.1 sable brush or Jap Art Brush (Figure 4QC), the latter seeming to give a better working point; spotting colors, and a good etching knife (Figure 40A) . Spotting colors on cards in sets of four-black, white, cold brown, and warm brown,-are most convenient for use. However, many prefer using lamp black, sepia, or. India ink ; others get several shades of black and brown in little water-color pans. For carbon prints, use pigment from the same color of carbon paper.

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M ethod.-As the image is more or less transparent, part of its brilliancy comes from the light reflected from the paper base thru the emulsion. Therefore the spotting should not be opaque but take on the transparent nature and texture of the surroundings. In using the set of spotting colors on cards, wet the brush with the lips and then apply to the color, taking up a small amount. Place the brush between the lips and remove with a rotating motion, which will put the color in a suitable condition to stick properly and will give a fine p:>int to the brush. Colors of this type are non-poisonous. Saliva is more effective than water for applying the colors. First fill in the spots on the darkest portions of the print, and as the color is used off the brush, work on the lighter parts. If the spots are small, a light touch of the point of the brush should make them invisible. If too much color is applied, it can at any time be wiped off with a damp piece of cloth, or it may be broken up or partly scraped off with the etching knife. When the color seems to have left the brush, if it is again moistened, it will usually be found to still contain considerable color. If the spots are larger, care must be taken not to fill in solid or the difference in light reflection will make them more conspicuous. A stippling touch or cross hatching, as is often used in retouching, will be found effective. Work lightly, going over the spot a second or third time, rather than trying to fill it in all at once. The strokes used in spotting will be less noticeable if they follow the general direction of the lines of the surroundings, or those in the backgrounds, draperies, etc. Not only can spots, scratches, and lines be obliterated so as to be scarcely visible, but modeling may be done on the face, and even objectionable features removed. When colors are not at hand that will match the exact shades of the print, a combination

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of two or more colors may be used. Spots that are darker than the surroundings must be remedied by the use of the etching knife. This should be of the best steel and sharpened similar to a chisel but with the bevel more nearly at right angles. If sharpened to a fine edge, vibration is likely to cause scratching and other troubles. Carefully scrape off the silver deposit from the spot until down to the surrounding tint, being careful not to go deeper or the spotting brush will have to be requisitioned to fill it up again. When carefully spotted, the picture is finished, unless to be air brushed, colored, or framed. 8. Air Brush Work.-With the modern demand for the artistic finish of portraits, the expert use of the air brush has come to be a necessary qualification of the first class photographer. For commercial finishing and the photo-retouching of prints from which engravers make cuts, it is indispensable. There are several good books2 available which are invaluable to one taking up the study of the air brush and its use. The air brush is a clever mechanical device but little larger than a fountain pen, which throws .a very fine spray of pigment (lamp black, sepia color, water color, etc.) from a cup which is attached to the side. The pressure, which should be from 30 to 40 pounds, is usually obtained from an air pump or a carbon dioxide tank. The results obtained are little less than wonderfuL It can be used not only for building up highlights and working in backgrounds on negatives, but also for finishing vignettes, improving prints, working up enlargements, coloring photographs, and for 2Stine: The Air Brush in Photography. Photo-Miniature No. 181: The Air Brush and the Photographer. Frazer: Treatise on the Air Brush. (This book pays special attention to photo-retouching.)

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many other things that will suggest themselves as occasion demands. Vignettes often appear unfinished on a large expanse of white paper. If a slight shadow is blown in at the sides to form a background, using a stencil to get a pleasing design, the picture will stand out, having greater roundness and life, as in Figure 22. Work of this kind can be done with but a few days practice. Often the bottom of. the vignette is too sharp or ir•

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Figure 41

East er Egg (air prush ed).

regular in shape, or vignetting may have been too close. A few minutes work with the air brush and suitable ' stencils will fill in and blend off such defects. Frisket paper and cement are often used instead of stencils to k eep definite portions of the print free from color. Portraits which are too flat may be remedied by filling in the shadows with lamp black or building up the highlights with white. A thin spray of gum arabic blown over the print will give added brilliancy. • t

FINISHING The air brush is also most effective in making more elaborate designs. The Easter egg picture (Figure 41) was first vignetted on a large sheet of paper. Then by means of a stencil consisting of two parts, the egg was blown in. Work of this type, especially in colors, is very effective and can be done in a few minutes. 9. Sketching.-As an alternative methop of finishing vignettes, sketching is occasionally resorted to, instead of the air brush. A .carbon pencil is used to work in designs in the draperies and backgrounds, or a coat may be entirely vignetted off and then sketched in with a pencil. Pictures of this type are termed "Sketch Portraits". 3 The signature is often sketched on the lower right corner of the prints. 10. Coloring.-In a short space, no adequate treatment of coloring can be attempted. The aim here is only to point out the desirability of coloring and the ease with which it can be done. In all the better studios there is a growing demand for artistic colored work, especally in the larger sizes. The effectiveness of doretypes, opals, and transparencies is decidedly improved if they are tinted in natural colors. Commercial workers find colored lantern slides much in demand by lecturers and others. There are three general types of coloring-oil, water, and pastel. Oil coloring is very permanent and undoubtedly the easiest for the beginner as mistakes may be rectified simply by rubbing off the color and starting over again. All that is needed is a set of a dozen assorted tubes of oil colors of good grade, a tube of medium or megilp, an old negative or a piece of glass for a palette, a few tooth picks, some cotton, and pos3Adamson: Sketch Portraiture.

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sibly a small brush or two. Some of the medium and a small amount of each necessary color is squeezed out on the glass. Apply the medium evenly over the surface of the print, rubbing off any surplus. This keeps the color from sinking in too much. In using the color, a small amount is taken up on some cotton and if too thick, mixed with a little medium. This is then applied to the appropriate portions. No especial care need be taken to prevent the color extending beyond the area where it is wanted, as it can easily be removed by rubbing at once with some cotton dampened with the medium. After the first portion is done, however, new colors must not overlap where applied. For small portions, use the cotton on a paper stump, or if preferred, use a small brush. When the picture has dried for half an hour, it may be rubbed down and blended mo.re evenly. After a few days, a dull finish varnish may be applied if desired. This will give more nearly the appearance of a painting. The use of a brush instead of cotton for coloring will increase this effect. In most cases a picture looks best when barely tinted, leaving one to guess whether it is colored or the result of some new process of color photography. Water colors, while often applied to prints by hand with a brush, are more convenient for large work, using the air brush as the medium of application. They are used extensively for pictures on glass, as lantern slides, doretypes, and opals. Water colors are more likely to fade than either oil or pastel. Pastel colors, which are on the order of soft crayons, give a delightful softness of tone and are best adapted to large work. The color is permanent, but it rubs off easily unless a spray of "fixative" is blown over it or it is framed under glass. In general, sepia prints are best for portraits which are to be colored, as the flesh tones on colored black and white prints tend to be too cold. Autumn

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views for coloring are best in sepia while winter scenes, and views containing much foliage or water, color more faithfully over black and white. It is advisable to clean prints with alcohol or oxgall before coloring in order to remove any grease or finger marks, as these may show up strongly after being colored, especially if the air brush is used. When prints do not take the colors properly, the surface may be slightly roughened with pumice powder. 11. Framing.-There is a great deal of fine art in properly framing pictures. Much can be learned of the laws of good taste in the relation between pictures and their frames, by a study of the framing done by the older experts, especially English and Spanish. The frame bears much the same relation to the picture that dress does to the person, the two functions in each case being protection and beauty. Mats.-When the picture space is filled with large objects and is to be viewed at a distance, a mat is desirable to isolate it from its surroundings. Pictures showing considerable action as well as those where the figures come close to the edge and seem crowded, are also improved by using mats. On the other hand, prints full of detail that are to be viewed at close range, do not need them. In general, the purpose of the mat is to increase the size of the picture space and to help isolate the picture from the background formed by the wall. Instead of using a mat, a picture may be mounted flat on a view mount, thus giving a similar effect. The shape and size of the mat or mount is necessarily determined by the picture. A panel picture would naturally require a long vertical border; a horizontal picture one of corresponding shape. Small pictures can stand a much larger mat proportionally than large ones, while pictures depicting action require larger ones than quiet scenes. A wide mat is also suita-

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ble when the picture contains several large objects; The margin at t~e top in horizontal pictures may be the same or _slightly less than at the sides. In vertical ones, it may be equal to the sides or slightly greater, but never as wide as at the bottom, which may well be from one-fourth to one-half wider than at the sides. The same general rules mentioned in regard to the color of mounts apply equally well in selecting the color of the mat or mount for pictures to be framed. Maulding.-Machine-made moulding, while generally used, is not always as desirable as moulding made for the individual picture. Especially designed mouldings sometimes contain details emblematic of the subject of the picture and show evidence of refinement and taste not found in stock mouldings. These latter, however, are quite satisfactory in the vast majority of cases. Âˇ The frame is but a continuation of the mat or mount. It must not be otherwise or it will detract interest from the picture itself. A frame may be beautiful but its beauty must be kept subservient to the picture. The color of the moulding is generally most harmonious if in the predominating color of the picture and mat. However, the general tone of the walls and hangings of the room affect the final result. The frame seldom looks well if as light as the lighest part of the picture or as dark as the darkest portion. Brightly colored and ornately carved mouldings are obj-ectionable as they violate the rules of good taste. However, a Âˇdull gold or silver beading is often helpful to accent or set off the picture. Prints in sepia may be placed in narrow gilt frames, if not too bright; colored prints go well in gold or green-gold frames; black and white prints are perhaps best in a shade of gray or black. The width of the moulding is governed by the

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same factors affecting the choice of a mat-the action displayed, the brilliancy of color, and the size of the :figures making up the picture. It also depends on whether or not a mat is used. Pictures with considerable action, with large :figures, or with bright colors, need wider moulding to help separate them from their surroundings. The moulding, however, should seldom be as wide as the mount. Depth and curve in the moulding gives the impression of distance, and so recessed moulding is suitable for landscapes showing perspective. Moulding made of :fine grained wood is more durable and satisfactory than that of plaster or other combinations. Walnut, mahogany, maple, oak, cherry, white pine, and several other woods are much used. The necessary materials for framing as given in the list of Finishing Supplies (Chapter III) are strips of moulding, a miter box with saw (preferably one in which the moulding can also be nailed), a sander for smoothing the ends of the moulding, glass, glass cutter, glue, backing material, hammer, and small brads or framing nails. After the moulding is cut to the proper lengths for the frame, the ends smoothed with the sander and glued and nailed together, the glass and backing are cut to the correct size. The glass is placed in the frame, the mat put in, if one is used, the picture properly spaced, face down, and then the cardboard or other backing added and made secure by brads. A line of glue is spread on the back of the moulding and the whole covered with heavy wrapping paper to exclude dust. Screw eyes are placed on the sides, near the top, so that the picture will hang as flat as possible. Large pictures are often suspended by two vertical wires from the moulding or other support in the room. "Pushless hangers" are used to a great extent in recent years as they make possible dispensing with the use of visible wires.

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12. Miscellaneous.-In the absence of an air brush which every photographer does not possess, the crayon sauce method is a very acceptable substitute in finishing vignettes. It is effective and cheap, but more mussy and inconvenient than the air brush. The mate1路ials necessary are black and sepia crayon sauce or pastel colors, cotton, a hard rubber eraser, and preferably some stencils. Working on a piece of blotter or rough cardboard so that the crayon won't slide too much, grind up a little of the crayon sauce or pastel color. In the absence of this the lead from a pencil may be used, rubbing it off on sand paper to obtain a powder. Take up a little of the fine crayon sauce on some cotton, which has been doubled over, and dab on the print in the space indicated in the air brushed print. (Figure 22.) With a sharpened end of the eraser, cut out sharp points. Lightly rub the whole with loose cotton in the direction of the lines to take off loose specks and to soften the work. A simple1路 method is to apply the sauce, using stencils as in the case of air brush work. This saves cutting out portions with the eraser. Elaborate designs can not be worked out satisfactorily. If the paper is too smooth to take the powder well, rub first with pumice powder or mix some of this with the crayon sauce. This will roughen the paper slightly, giving it more tooth. Any desired shade can be secured by using suitable mixtures of the two powders. Tinting.-Printing papers with a soft luster surface are often rendered more pleasing by being rubbed over uniforrnily with burnt sienna or other suitable shade of oil color, properly diluted with medium. This gives a decidedly different tone, not unlike that resulting from some of the regular toning processes. The brilliancy of lights and the luminosity of shad. ows may be increased by rubbing prints with one of the several available waxing solutions. Or floor

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wax of a good grade may be applied with a brush, the prints then being polished. This, however, gives a slightly yellowish tone. A coating of thick amyl acetate collodion is sometimes recommended as a water-proof protection for prints. They will look soiled when first coated but on drying show a beautiful hard semi-gloss finish.

CHAPTER XV'Il. PROJECTION PRINTING. (Enlarging.) Projection Printing is the process by which pictures are made either larger or smaller in size than the original. As generally understood, it has come to mean the making of larger sized prints from small negatives, altho enlarged negatives are often made from positives, and small doretypes and lantern slides from larger negatives.

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Âˇ Advantages.-While small prints are quite capable of having all the qualities that enter into the composition of an artistic picture, nevertheless the fact remains that they do not produce the same pictorial effect as those of larger size. A portion of a negative may enlarge to a pleasing picture, while used as a whole, it would be worthless because of poor composition. Enlarged paper negatives are often used for producing pictorial work, as they obscure obtrusive detail. Besides, many negatives are of such critical sharpness that prints made from them by the usual methods are often harsh, lacking the softness, depth, and roundness that are essential in producing an atmospheric effect. In connection with the enlarging process it is easier to obtain an agreeable degree ofÂˇdifjusion than by almost any other method. However, the modern enlarged print is quite different from the old fashioned enlargement which was often poor in quality and surrounded by a gaudy gilt frame. Its place has been taken by the modern projection print, not materially different from the best contact print which it resembles,-being made

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on similar paper, in the same style, and mounted in a folder in the same way. This manner of presentation has created such a call for "larger prints" that few studios refuse to make them. More often there is a request for six small prints and from three to six larger ones, rather than for a dozen smaller ones. Another advantage of projection printing lies in its removing the necessity for much of the retouching work. Formerly all negatives from a sitting were proof-retouched, and then the proofs were printed on printing-out paper by daylight. However, usually only one or two were chosen for later printing so that much of the retouching was in reality a waste of time. Now, many photographers do but the minimum of proof-retouching and then make slightly diffused projection proofs by artificial light. These may be the same size as the negative or somewhat enlarged. There is also a growing tendency in studio practice toward using only 5x7 negatives, and then making the prints in whatever size desired. Disadvantages.-The disadvantages of the enlarging process are few and more fancied than real. If a great many prints must be turned out in a short time, contact printing undoubtedly has the advantage. Also. for some kinds of commercial work where prints of microscopic sharpness are necessary, it is a question if the same degree of definition can be secured under working conditions even with the best of equipment, as when making. contact prints. Besides, the variety available surfaces is somewhat more limited in enlarging papers.

Equipment,_:_The kind of equipment necessary to produce perfect enlargements is not so important a factor as is the ability of the worker. Equipment is

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more a matter of preference and convenience, the latter being of special importance where speed is required. The essentials are a camera with holder for negatives; a lens, easel, and light. Besides these are needed the regular printing equipment as large trays for developing, short stop, fixing, and washing. For convenience of explanation, enlarging outfits may be divided into th1路ee classes: (a) Improvised Enlarging Outjits.-Owners of very small studios as well as most amateurs will likely prefer to construct their enlarging apparatus mainly from materials already at hand. For this purpose a view camera, 5x7, or 8x10, is admirably adapted. This one camera is sufficient for outdoor work, studio skylight use, and for enlarging. In the absence of a regular view outfit, a hand camera with removable back will be found suitable for the purpose. only the size of the negative to be enlarged as well as the speed is necessarily limited. Procure or make an extra back for the camera, .fitted with a groove into which the negative may slide. There should also be inserted in the back one flashed opal glass or two ground glass, one br two inches from the negative on the side furthest from the lens. If using daylight as a source of illumination, the rear of the extra back is 路fastened to an opening in a blocked out window, of such size that all stray light is excluded.1 A reflector outside the window at a 45掳 angle is necessary to secure even lighting. A better method, however, is to use artificial illumination placing the light in one room and the camera in another, bringing the extra back flush with the opening in the partition, thru which the light is received to illuminate the negative. An easel completes the apparatus. The general arrangement of the parts 1

See Fraprie (Ed.):

How to Make Enlargements.

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is the same as in the pictures shown of commercial outfits. • (b) Sta'n dard Horizon tal Outfits. These are procurable in a number of sizes and varieties. In some cases the light box is a part of the camera and is used as a •

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of Eafltman K odak Co.

Figure 42

Eastman Projection Printer.

single unit in one room; others are so arranged that the camera is placed in one room and the light source in another. While this arrangement is less convenient for adjusting the light, it serves to keep the negatives and the e11larging room cooler.

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(c) Projection Outfits, working in a vertical position, are perhaps more convenient than other types. The only disadvantage outside of increased cost, lies in the fact that very large pictures, e. g., life size, can not conveniently be made. Since the camera works in & vertical position, throwing the image down on the table, there is obviously a definite limit beyond which it can not be raised, thus limiting the size of the enlargement, at least without changing lenses. How•

By courtesy of Bu1·ke &: James, inc.

Figure 43

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Rexo Automatic Enlarger.

ever. the convenience and speed in producing excellent results is more than sufficient to counterbalance this limitation. Some cameras of this type are of automatic focus. (Figure 42.) As the camera is lowered to give a smaller enlargement, the lens is automatically pulled out

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at an increasing rate so that the image always remains in focus. Conversely, as the camera is raised, the distance between the lens and negative is lessened at a decreasing rate. The light is housed in a cotnpartment at the rear of the camera an~d of course move~ with it. Some cameras have supplementary lenses that fit over the regular lens and give different degrees of diffusion. Figure 43 illustrates a type of automatic enlarger where a prism is used on the lens to reflect .t he light rays down on the easel. This prism may ·b e removed and the enlargement made on a vertical easel when pictures of unusual By courtesy of Atlantic Photo Supplv Co. size are wanted. Figure 44. Another type is Lares-Master Projection Printer. · · built somewhat on the order of a regular printing machine but of course retains the projection feature. While not automatic •

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in focusing, it has the advantage that pictures of reduced size as well as enlargements may be made. It is also very convenient for printing tinted borders, vignetting, copying prints, etc. (Figure 44.) Enlarging lights are of two general types: these in which the light source has considerable area, and those which more nearly approach a point. Daylight and the M-shaped mercury vapor tubes are examples of the first kind. The mercury vapor light is very satisfactory, giving an intense ultra-violet light which is very actinic, while the M-shaped tube has sufficient surface to nicely illuminate an 8x10 negative uniformly. Added to this is the advantage that the light causes but little heat and uses but a small amount of current. Daylight is ca,pable of producing the best of results but is very slow, is subject to unexpected variability, and often is not available at all. When using either of these light sources, a couple of ground glass or one flashed opal glass shouJ.d be interposed between the light and the negative to secure as even illumination as possible. Arc lights and high powered electric bulbs are very efficient and entirely satisfactory if used under suitable conditions. As here the light is emitted from a small source, the center of the negative to be enlarged receives more illumination than the edges, since the center is nearest the light. To counterbalance this, a pair of condensing lenses are usually interposed between the light and the negative, resulting in the direction of the light rays being so changed as to evenly light the negative. These lenses must have a diameter greater than the diagonal of the negative. A piece of fine ground g-lass is often placed between the lenses to assist in diffusion of the light. Reflectors consisting of a number of mirrors or other suitable devices, so arranged as to give reasonably uniform illumination. are often used as a substitute for the condensing lenses.

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Arc lights are likely to vary in intensity and need occasional adjusting. Since arc lights and large electric bulbs generate considerable heat, suitable ventila路 tion must be arranged. Lenses as used for enlarging may be classified as rapid rectilinear, anastigmat, and soft focus. It is not necessary that enlarging lenses be highly corrected for chromatic aberration, i. e., to focus different colors in the same plane, as the negative to be enlarged from is in black and white. However, it is important that they be corrected for spherica1 aberration or the tendency to focus an object at a shorter distance thru the marginal zone than thru the center of the lens. The lens should also be free from the defect known as astigmatism or the inability to focus sharply both horizontal and vertical lines near the margin of the plate. Those desiring to enter more fully into the physics of lenses will find a number of books available dealing with the subject.2 For most portrait work, excessive sharpness is objectionable, since the pores of the skin, retouching marks, and other undesirable details would be magni路 tied and be too much in evidence in the larger pictures. So for work of this type, a rapid rectilinear lens is most suitable. One must not expect, however, to make a small negative with a rapid rectilinear lens, and then enlarge it, even with one that is more highly corrected, and get absolute sharpness. The slight diffusion while not particularly noticeable in the small print, is quite in evidence when an enlargement is made. A certain type of portraiture as well as much pictorial work is most pleas-ing when made with a soft focus lens. This focuses most of the rays of light in one plane, giving a sharp image. and yet at the same time a certain overlapping of images. This combinatSee Harting: Optics /0'1' Photographers.

212

PHOTOGRAPHIC PRINTING

tion of sharp and diffused images is very attractive if the softening is kept within reasonable limits. Correctly used, it gives results having no resemblance to an out-of-focus picture. Critical sharpness is necessary in many kinds of commercial, technical, and scientific work. This is secured by making the original with an anastigmatic lens and then enlarging with the same type, being careful to secure accurate路 focusing in each case. This lens has the advantage that the exposure may be shortened with no loss of definition, by using it wide open. In using any kind of a lens, especial care must be taken in cold weather that moisture does not form on it, thus giving a flat, fogged appearance to the print. Enlarging Papers are available in a variety of surfaces, and show considerable variation in speed. Papers for enlarging fall under two general classifications: (a) fast chloride papers, (b) bromide papers. The chloride papers are perhaps made in a greater variety of surfaces and by more manufacturers than the bromide papers but their contrast is largely determined when the emulsion is prepared. On the other hand, bromide papers like plates are capable of giving increased contrast by variations in the time of exposure and development. The bromide papers are also faster as a rule. Some papers being a combination of the two types partake of the characteristics of each. For portrait work, a smooth matte or slightly rough matte with sheen is very suitable, either in white or buff. If to be colored in oil, the rougher surfaces are preferred by many. In general, a rougher paper is more pleasing as the size of the objects in the picture is increased. For commercial work, particularly if intended for reproduction, a glossy paper is best.

PROJECTION PRINTING

218

MAKING THE ENLARGEMENT.

It is essential tha~ the enlarging room be considerably darker than the printing room which is used for the slower papers. Certain kinds of enlarging papzrs are fifty times as sensitive as some of the slower contact papers, so it can readily be seen that a small amount of white or yellow light that might be safe for contact papers would quickly fog the faster ones. The safelights should be of an orange color.

Focusing is a simple matter on the automatic machines. Simply insert the negative in the rack, turn on the light, and raise or lower the camera until an image of the desired size is obtained. Cover the lens with a piece of orange glass while placing the paper in position, remove, and expose. With most enlarging outfits, the procedure is not quite so simple. After the negative is placed in position, the easel on which the image is projected, is movÂŁd forward or backward until the image is of the proper size. Then rack the front of the camera in and out until the image is in sharp focus. This will probably result in changing the size of the picture. It is not difficult, tho, to learn to manipulate both the easel and the front of the camera at once, resulting in the getting of a sharp image and the desired size at the same time. Focusing is made easier by using white oilcloth as a covering for the easel. When focusing, select some sharply defined portion of the image, as the catch-light in the eye, for observation. The method used in securing the correct range in artillery firing can be used to good advantage here. The procedure there when a range is known to be surely under is to advance 400 to 800 yards in order to get a range that is surely over. Then the next salvo . is fired at the intermediate range. So in focusing, rack

t\:) ~

Ci ~

z '4l Figure 45 Contact Print.

Figure 46. Diffusion thru Glass

Figure 47. Diffusion by Projection, using Soft Focus Lens .

•

PROJECTION PRINTING

21:5

the lens board out until the image starts to blur, then back a fraction of an inch until it passes the sharpest pJint and starts to blur again, then out half the distance it was moved back. If the negative is too dense to focus, another negative may be substituted for focusing, or the distance may be determined from the formula = _.!: + ~ , where f is the focal length, p the distance frorl theP negative to the optical center, and p' the distance from the image to the optical center of the lens. (Also see Table D in the Appendix.) Soft focus lenses are more difficult to focus since the diffusion is so great as to disguise when the image is sharpest, especially if the lens is used wide open. This type of lens should be stopped down about onethird when focusing and then opened up wider when making the exposure if greater diffusion is desired.

Securing Diffusion or Softness.-(See Experiment 20.) The most pleasing quality of diffusion may perhaps be obtained by using the type of lens just mentioned wide open and inserting a star-shaped diaphram. The greater portion of the light going thru the center gives a sharp image; the small amount passing thru the points of the star of course goes 'thru the outer part of the lens. This results in a fairly sharp image and lighter overlapping ones, giving a diffused effect. (Figure 47.) Comparison with Figure 45, a contact print, and with Figure 46, made by printing for part of the time thru glass. givE's an idea of the effects obtainable. Some anastigmatic lenses have a diffusion device that may be employed to advantage. In case no soft focus or diffusion lens is at hand. effects that compare quite favorably may be obtained by enlarging thru black chiffon, tulle, or similar material. Cut openings, at least the size of the lens, in two pieces of car-dboard. Cover this opening in one card with one to five thicknesses of the material mentioned

216

PHOTOGRAPHIC PRiNTING

and over this fasten the other card so that the openings coincide. This is then held close in front of the lens during part or all of the exposure, according to the degree of diffusion required. Perhaps two thicknesses of chiffon, held against the lens for half the time of exposure, will best suit the average taste. Five thicknesses held in front of the lens for the entire exposure would result in one of those decidedly impressionistic or dreamy pictures, sometimes passed off as pictorial work. In such a case, the exposure would necessarily be prolonged. If the negative has sufficient contrast to permit its scale being reduced in the print, the following method is sugge路sted. Fasten a piece of silk bolting cloth of fine mesh to a piece of plate glass as large as the ;largest print for which it is to be used. If a decided linen effect is wanted, place the plate glass so that the bolting cloth is in contact with the enlarging paper. If slightly more softness is desired, reverse the glass so that the bolting cloth is on the side furthest from the paper. The light lines on the paper made by the mesh of the bolting cloth are almost invisible in the highlights, but in the shadows introduce a certain amount of white, thus naturally reducing the contrast. Engravers' process screens or photographic copies from them are sometimes recommended as good substitutes for the bolting cloth. Pleasing effects may also be secured by gradually opening or closing the diaphram during part of the exposure, and then leaving it open for the remainder of the time at a point which will give the degree of diffusion wanted. Exposure.-As bromide paper is extremely sensitive, care must be taken in using it to protect it from the light while being placed on the easel. If the lens is capped with an orange glass or filter after focusing, there will be light enough to place the paper

PROJECTION PRINTING

21'7

properly without any danger of fogging. Still better, attach to the camera an enlarging shutter fitted with orange celluloid wings. When closed, this permits an orange-color€d image to be seen on the easel; when opened by a bulb in the usual way, the exposure is made. The methods of obtaining correct exposure on contact papers, discussed in Chapters VIII and XI, apply equally to enlarging papers and need not be repeated. When using bromide papers, however, it should be borne in mind that correct exposure is more of a variable quantity. Cutting down the exposure slightly and increasing the time of development will give added contrast. When the lens is stopped down to increase the definition and the depth of focus, the time of exposure must be increased. In making negatives, the relative exposure varies with the square of the f value of the stop. i. e., f 8 requires four times the exposure of f 4. The f value as marked on the lens for negative making, however, is not the f value used for enlarging. Here it is found by dividing the distance from the optical center of the lens to the plane where the image is projected (the easel), by the diameter of the stop being used. Undoubtedly the simplest method of judging exposure is by inspection of the image on the easel after it has been focused and stopped down as desired. This is the method ordinarily used in exposing plates in the camera, and here where the image is lacking in color it should be easier. It is well to remember, tho, that if a certain enlargement has been made 8x10 and the next one is increased to twice that diameter, giving a 16x20 picture, the light coming thru the same lens opening will necessarily cover four times the space and consequently the exposure must be made four times as long. Increasing the diameter three times would necessitate nine times as long an exposure. (See Experiment 19.)

218

PHOTOGRAPHIC PRINTING

If a record is kept of the correct exposure of contact paper for a given negative and also of the correct enlarging exposure for a given size and stop, it will be found that this same ratio holds good for other negatives under similar conditions. That is, if the contact exposure is 10 seconds and the exposure for an llx14 enlargement is 20 seconds, all negatives requiring the same contact exposure will take 20 seconds for the same size enlargement. Enlarged or reduced positives on glass, such as lantern slides, opals, and doretypes can be made on any type of enlarging outfit in which the image can be brought to a focus at the size desired. By the substitution of a lens of shorter or longer focal length, almost any size image within reasonable limits can be formed. Machines of the projection type, having horizontal easels, are most convenient for the making of positives, as the glass plate is placed flat on the easel and the exposure made as for prints, except that the time required is much less.

Dodging.-If frequently happens that some part of the enlargement prints either too light or too dark. The correction of such defects is much easier when printing by projection than by contact. A part that does not print dark enough can be exposed morefully by using a cardboard having an opening cut in it the approximate shape and of slightly smaller size than the part of the picture that is unsatisfactory. By holding this mask a few inches in front of the paper for a short time after the regular exposure has been completed, extra exposure is given the desired portion. The mask must be kept in motion during the exposure so that no image of the edge of the opening is formed on the paper. Similarly. if any portion prints too dark, a piece of cardboard cut to the desired size and shape, or even a mass of cotton attached to a wire, may be

PROJECTION PRINTING

219

used to shield the part that prints too rapidly. It is thus seen that an unlimited amount of improvement may be effected by careful dodging. Sometimes the lines of tall buildings slant in. This distortion may be corrected by tilting the easel until the Jines become parallel and then by stopping down the !ens to secure depth of focus. Vignetting is accomplished by cutting an opening of the shape desired, in a piece of cardboard, postoffic~ paper, or other non-actinic material, about haJlf the size of the image, and holding the card between the lens and the pape1路 when making the exposure. In order to determine the size opening necessary, first move the easel toward the lens and focus so that the image is about half the size of the finished picture. Place the cardboard on the easel and mark out the proper shape for the vignette, following the principles outlined in Chapter IX on Vignetting. Cut out the opening along the line marked. A serrated or sawtoothed edge will result in a softening of the outline of the vignette. Now re-focus the image to the size desired when finished, and when making the exposure hold the mask at sufficient distance from the printing paper that the opening will just include the portion of the picture desired. The mask should be moved slightly during exposure to soften the outline. After a number of masks or cards with vignette openings have been accumulated, it will be found that the ones on hand or a combination of them will fit almost any new vignette. If preferred, the opening may be cut in a piece of 6x8 post-office paper, fastened over a 5x7 opening in a large card. In this way the cutting will be easier than when using cardboard. Development.-lt is suggested that the formulae recommended by the manufacturer of the particular

220

PHOTOGRAPHIC PRINTING

brand of paper used be followed. If they do not give the results desired, they may be varied as described in Chapter XI on Development. For many kinds of enlarging paper, it is often more satisfactory to use a developer double the strength used for contact papers. Superior results are obtained from most bromide papers by so timing the exposure that the pausing point or complete reduction of the exposed silver salts, will be reached in two to three minutes. Overexposure and decided underdevelopment will result in muddy gray or greenish black and white prints, and yellow sepias. Decided underexposure resulting in considerable forcing in the developer, is likely to give yellowish whites and perhaps fog. Bromide papers have more latitude than chloride papers and so considerable variation in contrast may be secured by proper manipulation. (See Experiment 21.) A properly exposed print may seem dark enough in a minute or so, but if allowed to remain an extra minute, development of the highlights will be seen to stop while the shadows continue to build up, resulting in added brilliancy, better modeling in the highlights, and richer blacks. For very thin negatives, better results are obtained by cutting down the volume of light by stopping down the lens, and then increasing the length of exposure. While bromide papers have a longer scale of gradation than most chloride papers, still occasionally the negative may be too contrasty, i. e .â&#x20AC;˘ have a longer scale than the paper can reproduce. In this case, develop in a dilute developer with but little bromide, at least until the entire scale of gradation is visible. Action may then be completed in the regular developer if necessary to get sufficient density. The weaker developer seems to produce less contrast, the explanation being as follows: A certain amount of the developer diffuses or

PROJECTION PRINTING

221

soaks into the pores of the emulsion. When this is used up in reducing the silver salts, further development can take place only as fresh developer diffuses into the emulsion to replace the exhausted part. In the case of the weak developer, there might be sufficiâ&#x201A;Źnt chemicals present to carry on action in the highlights where only a small amount of exposed silver salts is present, but in the shadows, the exchange of developer thru the pores of the emulsion would not be rapid enough to continue development at the maximum rate, thus resulting in the shadows being held back, giving decreased contrast. In the case of a more concentrated developer, a greater quantity of the developing reagents is present in a given amount of developer in the pores of the emulsion at any one time, and the exchange keeps the shadow2 developing at a more normal rate. Soft and contrast developers may be necessary at times. especially for portrait papers, which are not made in as many degrees of contrast as the commercial enlarging papers. Fixing, Washing, and Drying.-The directions already given in previous chapters apply with equal force to enlarging work. Greater care must be exercised, however. in the handling of enlargements as they more easily become bent or cracked than smaller prints. Toning.-Most enlarging papers with their faster coarse-grained emulsions, tend to give rather cold tones when put thru thP. hypo alum sepia bath. For this reason it is generally better to tone them by the redevelopment method. Finishing.-The smaller sized projection prints are usually mounted on cards or in folders in the same way as contact prints. Larger ones may look best printed with a white margin, plate-sunk, and framed.

222

PHOTOGRAPHIC PRINTING

Life Size Enlargements.-Prints as large as 30x72 can be made by using a large easel for the exposure considerably further away from the lens than the ordinary one. If the easel is covered with white oilcloth, this may be folded up at the bottom to form a trough to contain the developing 51olution so that development may be carried on while the paper is still on the easel. When exposure is complete, tilt the easel at a little angle so that the developer will run back into the trough. Saturate a large handful of cotton with developer of half strength, using Plenty of bromide, and apply quickly to the print. Continue until development is complete, apply short stop in the same manner, and then fix by running thru a tray of fixing bath, like a roll of film.

CHAPTER XVIII. COMMERCIAL PRINTING.

Commercial Printing covers an extensive field and can here be discussed only in respect to those points which come within the scope of the average photographer. Commercial work of one sort or another often comes to the studio worker or even to the good ama:tâ&#x201A;Źur, and the ability to handle it satisfactorily is often a valuable asset. Much of the work is of course similar to the portrait printing already described but there are a number of points of difference. As taken up here, commercial printing includes not only the kinds of work done by the regular commercial photographer, but also the general methods applicable to amateur printing and finishing. Standards.-Unfortunately, most amateur finishers turn out prints hurriedly without due regard to th ~ treatment of individual negatives to secure proper results, so that prints of this type seldom compare with average portrait work. Where a little more attention can be given it, the results will repay the extra work. That vast class of commercial work, including machines. automobiles, scientific work, etc., which is p::oducâ&#x201A;Źd for illustrations, records, salesmen's use, and other purposes, must reach a much higher standard than either amateur finishing or portrait work. The usual studio customer has no very clear conception of when a print is technically p~rfect, but manufacturers and others for whom commercial work is produced, know exactly what the print should show and whether it is properly made. A print a little too dark or too

224

PHOTOGRAPHIC PRINTING

light, too flat or too contrasty, or with an imperfect gloss, will not answer the requirements at all. Consequently, even more attention to detail is necessary than for other kinds of work.

Preparation of the Negative.-Few negatives as first made are suitable for most kinds of commercial work. Many need to be reduced or intensified, while often they need considerable work with the retoucher's pencil, spotting brush, or etcher. Pin holes and scratches need to be filled in, unsightedly blemishes in the original object covered up, telephone wires and oth:r objectionable features spotted or etched out. Some negatives of machines are vignetted, but most of them must be blocked. Cut glass usually stands out best where the emulsion around the object has been removed, leaving a pure black ground in the finished picture. Air brush work on the negative will often save considerable dodging when printing. As suggrsted in Chapter VIII, a dilute application of water color over the thin p:>rtion of the negative is often resorted b. in order to hold back the light, a red or yellow color having a decided effect, and blue much less. Dry yellow or red color mixed with plastocine, or modeling clay, and dabbed on the back of the negative over thin portions is also helpful. Blocking.-Negatives of a large class of subjects as machines, tools, musical instruments, and nearly all small articles where the pictures are used for catalog illustrations and other advertising purposes, have the background blocked out so that it will print pure white. The materials most generally used for blocking (see Figure 48) are opaque, small and large opaque brushes, ruling pen, triangle, and French curves. There are many formulae for preparing opaque1 but time is 1 Photo-Miniature No. 173: Figures, Facts and Formulae of Photography.

COMMERCIAL PRINTING

225

usually saved and better results obtained by using the commercial product. A very convenient arrangement for blocking is easily made from a wooden box about 18xl2", 10" high. An opening, 9xll, is cut in the top, and a piece of 10x12 plate glass is fitted over the opening in such a way that the top surface of the glass is only slightly higher than the remaining surface of the box. One side of the box is left open. A mirror or piece of white blotting paper to serve as a reflector should be placed diagonally across the interior of the box from the lower outer edge to the upper inner one. The box

~~ .

Figure 48-Blocking Materials.

is best used with the open side next a window with the shade pulled down about an inch below and close to the top of the box. Commercial work must usually be sharp in outline, so films and especially plates should be blocked on the emulsion side. This must first be rubbed with cotton slightly dampened with alcohol to remove any grease

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PHOTOGRAPHIC PRINTING

or finger marks, or difficulty may be experienced in getting the opaque to stick uniformly. It is also well for beginners to first go over it with. negative or lantern slide varnish. Then if opaque gets on the image, it may be rubbed off that part with a damp cloth without injuring the emulsion. The opaque should be mixed with water to the consistency of India ink. If trouble is experienced with the buckling of commercial films, mix the opaque with turpentine, instâ&#x201A;Źad. Place the negative, emulsion side up. on the glass top of the blocking stand ; then partly fill the ruling pen with opaque, and using a ruler or more conveniently an amber triangle, carefully outline the straight portions of the subject, making a line a thirty-second of an inch or more in thickness. Similarly, using a French curve, outline a11 curved portions of the image. By having two or three curves of varying sizes and shapes, some portion will likely be found that will fit any curve in the negative. Very small curves and decidedly irregular edges may have to be outlined with the small brush. However, a good draughtsman will use the ruling pen if at all possible, as better clear-cut lines are obtained in that way. Thm, using the large brush, opaque out all the remaining background, being careful not to run over the outlined edge on to the image. If a more diffused outline is dÂŁsired in any portion, work on the back of the negative and stipple that part. In this case, the opaque should be considerably thinned or else a gray or blue water color used. Etching.-Cut glass, silverware, and similar articles often show up best against a pure black ground. (See Figure 49.) This is more easily produced on plates than on films as they are more easily stripped. With the etching knife, carefully remove the emulsion for about an eighth of an inch all around the :figure. Then to the emulsion outside of the clear line, apply

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with cotton the following stripping solution. being· careful that none gets over on the image: Water Sodium fluoride Hydrochloric acid

•

32 oz. ~

oz. 1 oz.

1 liter 15 g. 30 g.

After a minute or so the emulsion should leave the glass easily. This solution can be used over a number of tin1es. It -is also very useful for removing the emulsion from old plates when clear glass is wanted, being more convenient than hot water. Lettering. A very convenient method of putting titles on prints is to print the lettering on very thin celluloid the size of the negative, using India drawing ink. Fasten the celluloid to the emulsion side of the neg·ative so that the lettering is next the emulsion.

Figure 49

Etched Piece.

,. •

The celluloid being so thin will cause no noticeable diffusion in the print: Or if only one or two prints are needed, print the titles on the sensitive paper before exposure, using a carbon pencil. After exposure and before development, remove the pencil marks with an eraser.

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PHOTOGRAPHIC PRINTING

Commercial Printing Papers are made in several degrees of contrast. This greater variety is made necessary by the kinds of work the commercial photographer is called upon to do. If it is a matter of amateur finishing, he finds that owing to the inexperience of many amateurs and the poor lighting conditions under which many of the negatives are made, there are not two out of a dozen with similar contrast. Then again, inuch professional commercial work has to be done under all sorts of conditions, so that some results will be flat and others contrasty. The emulsion on commercial papers is also made to work much faster than that on portrait papers, as here the element of time is much more an important factor and there is often necessity for quantity production. This greater speed in the papers means that the commercial printer must be very alert in securing correct exposure and development. It has been customary for the majority of commercial prints to be made on a glossy surface of paper. This involves considerable work in squeegeeing which is often needless, as many types of outdoor commercial subjects would appear just as well on a matte or semi-matte paper. The latter is especially good for groups and other subjects where a reasonable degree of detail is wanted. A fairly smooth paper with slight sheen and rather more contrast than will give truthful rendering is generally considered best for amateur finishing. Printing Maehine.-Regular printers as already described are satisfactory except in the matter of speed. If the printing surface is 16x20; then four 8x10 negatives may be printed at once, shading the thin ones with one or more thicknesses of tissue paper, placed on the ground glass. Machines used for commercial work should have six or more electric bulbs

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to facilitate dodging. Amateur finishing printers are constructed with the view of turning out thousands of prints · a day. (Figure 50.) Exposure. In using portrait papers, best results are obtained by exposing for a minimum of ten seconds, as too short an exposure tends to flatten, resulting in loss of brilliancy. Commercial papers. however. are made so as to give • good results with con- · siderably less exposure, ·amateur nega• tives usually being given only from two By courtesy of the Pa-ko Corporution. to three seconds. Such Figure 50 Amateur Printer. a short exposure wilJ naturally result in much more variation from correct standards. What constitutes correct exposure never varies and may well be stated again. A print is correctly exposed if on full development to the pausing point ·i t is neither too dark nor too light. Or in other words, the light action must have affected the silver salts of the emulsion sufficiently that when they are requced to the metallic state by the developer, the print is of the desired density. Dodging must often be resorted to in order to bring out or hold back certain portions of the print. In addition to the tissue paper method already described, the unscrewing of electric bulbs underneath thin portions and the substitution of larger ones under

•

230

PHOTOGRAPHIC PRINTING

dense parts of the negative is quite effective. Vignetting.-Heavy machinery, automobiles, and other such objects look best if blocked out except at the base where a small amount of support is often left. For an 8xl0 negative, a piece of blotter about 4x12 is used to eliminate those portions of the background or foreground that are not wanted. It should be cut with serrated edges on the side next the picture so as to secure good blending. The blotter is placed on the ground glass of the printing machine and the negative put in position over it and printed. If the image does not blend off properly, use teased-out cotton over the blotter as when making portrait vignettes. Figures 16 and 43 show this type of vignette. Quick Printing.-lt often happens that prints must be made from negatives soon after development. Rapid drying methods, however, are likely to prove injurious to the negative, so a quicker and more convenient method is often used. Cover the emulsion side of the wet negative with a piece of celluloid, using the thinnest variety obtainable. If films are being used, it may be necessary to cover the back of the negative with a similar piece of celluloid. Roll down lightly to expel surplus moisture and to secure even contact. The wet negative may now be printed the same as any negative. The celluloid may be removed after printing or be left permanently for protection. Developers.-In order to speed up development, commercial devc lopers usually contain a greater quantity of sodium carbonate than portrait developers. To further increase contrast, the metol may be reduced and the hydrochinon increased, as described in Chapter XI, but as the paper is available in several degrees of contrast, there is less occasion for varying the developer. If a softer effect, i. e., a longer scale of grada. tion in the print, is wanted, a normal portrait paper

COMMERCIAL PRINTING

281

developer may be used, possibly reducing the carbonate by one-fourth. For ordinary usage, however, the following largely used formula will be found to be satisfactory: Water Metol Sodium sulphite Hydrochinon Sodium carbonate Potassium bromide

30 oz. 900 21 gr. 1.4 t oz. 22. 90 gr. 6 1 oz. 13 gr. 29 15 gr. 1

c.c. g. g. g. g. g.

Dilute with equal parts of water for use. The amount of potassium bromide specified will prevent fog for the time necessary to develop most papers. It will give the rather cold tone which seems to be preferred by most amateur finishers and commercial workers. Altho prints for reproduction are often wanted cold in tone, there seems no sufficient reason for this idea, as a rather warm-toned black and white print usually reproduces better. More bromide may be added when using, as in the case of the portrait developer, if necessary to keep the whites clear, or to produce the desired color. Some commercial papers are best developed at a temperature of 65°F. (18.3°C.); others at 70°F. (21.1C 0 . ) . Non-abrasion developer.-(See Experiment 12.) Vet·y often abrasion marks appear on glossy papers. They are generally in the form of fine lines running at all angles across the paper. (Chapter XV.) To prevent this, add a small quantity of potassium iodide to the regular developer. i grain to the ounce (.025 gram per 100 c.c.) will usually be sufficient. Unless the print is too contrasty, use as little as will prevent the showing of the marks, as any considerable amount tends to flatten the print. The canary-yellow color caused by the iodide should disappear when the prints have been in the fixing bath for the regular time. In addition to the potassium iodide, a similar quantity of

282

PHOTOGRAPHIC PRINTING

potassium cyanide is sQmetimes used. Development.-Because of the difference in manufacture, and of the variations in the developer used, commercial and amateur papers develop 路much faster than portrait papers. The softer grades usually complete development in 45 seconds ; the medium in 30 seconds; and hard or contrast papers in 20 seconds. Less development than indicated may result in flat, mottled, brownish prints. As stated in a previous chapter, regardless of paper, composition of the developer, temperature, and other factors, a print is completely developed when all the exposed silver salts are reduced to metallic silver. If exposure is correct, the print will develop, increasing in density to the proper depth, and will then pause for a short time before the highlights begin to veil over. This is when it should be removed from the developer. Prints for commercial work should be a shade lighter than portraits, keeping toward the soft end of the scale, thus getting a longer scale and better gradations. Because of the greater speed of development and the large number of prints developed at a time, quick judgment must be exercised to secure uniformly good results. A number of negatives are often standardized as to exposure and printed upon a single sheet of paper, which is developed, fixed, and washed before being cut up. An expert can turn out great quantities of amateur prints in a day by this method. Fixing and Washing.-After development is complete. place the prints in the short stop bath for a few seconds. Then fix in the regular acid fixing bath for ten to fifteen minutes, being careful that the prints are kept separated to insure complete removal of the unaffected silver salts. Washing is carried on in the . usual manner, except that greater care must be taken

COMMERCIAL PRINTING

288

not to crack. or otherwise injure the emulsion of the prints. Single weight papn, especially of the glossy variety, is easily damaged by careless handling. Drying;-Amateur finishers usually run the prints thru one of the commercial drying machines (Figure 38), resulting in the prints being completely dried and reasonably well flattened in a few minutes. One dryer will care for several hundred prints an hour. Commercial prints that are not on glossy paper are often dried in the same manner. Glossy prints must be especially well hardened, but even then if put thru the dryer, they are likely to stick where the emulsion comes in contact with the blotters, or at least pick up some lint. If desired, commercial and amateur prints may be dried and flattened the same as portrait work. Finishing.-Amateur prints are perhaps most usually made on a semi-gloss paper with a n&.rrow white margin and require no further treatment. Commercial prints, especially for reproduction or for salesmen's books or similar purposes, are generally preferred with a very high gloss. At one time, when printing-out papers were more extensively used, this was secured by burnishing, that is, passing between hot rollers. Now they are squeegeed on ferrotype or other plates having a smooth, shiny surface. Ferrotyping.-Ferrotype plates are medium heavy tins, coated on one side with a material capable of taking a high polish. These have been so much used for securing a high gloss on prints that the process may well be called ferrotyping. For this purpose, only the glossy grades of printing paper are suitable. First secure as high a polish as possible on the ferrotype plates. If they are new, simply washing in hot water and polishing with a soft cloth is all that is needed. As the plates get older and become scratched,

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the prints sometimes stick so tightly in spots that they can not be removed except by scraping. To prevent this, after the plates are polished, apply a drop or two of the following waxing solution and polish again: Benzine Paraffin

3 oz. 15 gr.

90 c.c. 1 g.

Only the thinnest fflm of this wax is needed, so the more it can be rubbed off the better. If power is available, nothing is more satisfactory than a soft buffing wheel for polishing the plates. As a substitute for the waxing solution given, rub a piece of castile soap on a soft cloth and apply to the plates before polishing. Probably the best method to keep the plates in good condition and prevent sticking is to wash with hot water and castile soap each time after using, and then to rinse in warm water. As soon as the prints are sufficiently washed to remove all hypo, slide one of the ferrotype plates into the water and the print over on it. Remove and squeegee into as thoro contact as possible. The heavy print rollers are good, altho some prefer the flat rubber squeegee. If much work of this kind is to be done, an ordinary clothes wringer or power roller will be found most convenient for the purpose. The ferrotype plates with the prints are now set aside to dry, care being taken that the faces do not become scratched. If speed is a factor to be considered, artificial heat may be used to hasten drying. However, if the prints become too warm, they may leave the plates too soon in spots, with the result that the gloss is imperfect. Such prints will seldom lie flat and may need ferrot,t;路p .. ing again. To secure the best gloss, the emulsion should be hardened only enough to prevent sticking, the plates should be clean and have a high polish, and the prints must be rolled down in perfect contact.

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Heavy celluloid plates are corning somewhat into 路 use as a substitute for the regular ferrotype plates. They have the advantage that prints are less liable to stick and that they may be used on both sides. However, they are more easily scratched and then become worthless. While heavy glass plates give a fine glosEZ., there is too much t6!ndency for the prints to stick. Backing.-In order to make them stiffer and less liable to become torn, cornrnerciail prints are often backed with muslin or other suitable material. The print is rolled in place on the ferrotype plate and given a good coating of paste. Over this a piece of bleached muslin which has been previously dampened (wet and wrung out) is laid and then rolled flat. After drying, the print and muslin are trimmed together. A pr<.paredgurnrned Hollandcloth (used extensively by book binders) is used for backing by many commercial photographers. 'It is only necessary to dampen the gummed surface and apply to the back of the print on the ferrotype plate. If no regular backing is desired, a coating of gelatine applied to the back will make it lie flat. (Fir formula and method see Chapter XIII.) Hinges.-Many classes of work, especially prints to be used by traveling salesmen, must be mounted with a hinge. This is done so that the prints may be bound in portfolio form and opened time after time without cracking the prints. The hinges are made of strips of printing paper the same as is used for the prints. The paper is cut into strips about an inch wide, then fixed and washed without being exposed or developed. A strip is placed face down almost touching the print on the ferrotype plate, on the side or end that will be on the left when the print is viewed in the usual way. Prints that are to be provided with hinges should be so printed that trimming will be unnecessary on that side.

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Mounting.-Altho paste is often used as an adhesive in mounting commercial work on cards, it is so much less convenient and unsatisfactory than the dry mounting method that space need not be taken to describe its use. Dry mounting has the advantage of permitting prints to be mounted perfectly flat even on very thin supports. It is easily done, does not get the mount soiled, and the print is ready for delivery in a few seconds. It also protects the back of the print from any injurious ingredients in the mount. Dry mounting tissue2 which is thin tissue paper saturated with a solution of shellac can be obtained ready for use, both in the most common sizes used for prints and in long rolls. A sheet of the mounting tissue is attached to the back of the print by touching it in two or three places with a hot iron. The print is then turned face up, and the print and adherent tissue are trimmed together. The print is now laid in position on the mount and placed under pressure for a few seconds in a dry mounting press, heated to about 240째F. (l15째C.). The heat and pressure will cause the shellac to melt and to adhere both to the mount and print. If the temperature is too great, the tissue will stick to the mount and not to the print; if too low, it will adhere to the print and not to the mount. A flatiron is satisfactory for use in the same way in the case of small prints. However, if the iron must be applied twice in order to cover the print, a slight line or impression of the edge of the iron is likely to show across it.

Line Drawings.-Many times, pictures of printed matter, line drawings; etc., are required. If the work is to be professional in appearance, the printed matter or Une work must be a good black, 2

See Wall:

Dictionary of Photography.

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and the remainder of the print pure white. If the negative has not sufficient contrast even after having been intensified as much as possible, then resort must be made to work on the print. Expose somewhat more than normal, then develop until the print is a little too dark. The lines will be a little deeper than necessary while the background is somewhat fogged, i. e., shows a slight deposit of silver. To remove this deposit, place the print in the following reducer or go over the print with cotton saturated with the solution: Cyanide-Iodide Reducer. A Potassium cyanide

Saturated solution. B

Water Potassium iodide Iodine crystals ( resublimed)

12 oz. ! oz. ! oz.

360 c.c.

21 g. 7 g.

For use take 1 part (A), 1 part (B), and 10 to 30 parts water. CAUTION: POTASSIUM CYANIDE IN ANY FORM IS A DEADLY POISON, A VERY SMALL AMOUNT BEING SUFFICIENT TO CAUSE INSTANT DEATH. NEVER LET IT COME IN CONTACT WITH AN ACID AS THE COMBINATION WILL RESULT IN THE FORMATION OF HYDROCYANIC ACID GAS WHICH IS EXTREMELY POISONOUS IF INHALED. Iodine while almost insoluble in pure water is easily dissolved in a solution of potassium iodide. Altho both the cyanide and the iodine have a solvent action on the silver image, the main reaction is between the iodine and the silver of the image. This forms silver iodide which is readily soluble in a solution of potassium cyanide. The solution may be used fairly strong for removing stains or for completely removing parts of the image, but for slight local or general reduction it

238

PHOTOGRAPHIC PRINTING

should be used much weaker. Prints of line drawings or reading matter should be placed in a fairly weak solution until the background is almost a pure white. Then the prints are placed in running water and washed for a few minutes to stop further action. As reduction continues for a few seconds, it is well to remove the prints just before they are light enough. Almost hopeless prints are often changed into very acceptable ones by this method. The same bath may be used for reducing any prints that are too dark. However, as practically the same amount of silver is removed from all parts, the contrast is rapidly increased, so that if carried too far the highlights become chalky. Vignettes may be made from solid prints by using a strong solution of the reducer locally. When used in this way, the reducer should be applied to the print which after a few seconds is plunged into running water, and then the reducer applied again, the process being repeated as often as necessary. If too strong a solution is used, or if there is too great a disproportion in the amounts of cyanide and iodine used, or if the print is held in the air without immersion in water during the reduction work, stains are likely to result. This reducer is also suitable for lantern slides, transparencies, and similar work, as the color is not changed by its action. It works very slowly on sepia prints. If abrasion marks resist other methods, swabbing the wet print with a weak solution of this reducer will be found effective. Shaded Ink Drawings.-Pictures of automobiles and similar articles are often wanted for reproduction in newspapers. For this purpose, a line drawing is better than a half-tone. This may be secured by going around the outline of the picture with water-proof India ink, using a ruling pen or other suitable pen or

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239

COMMERCIAL PRINTING

•

brush. Any rd esired shading may also be done. After the ink has dried, the silver image may be removed with the cyanide-iodide reduc' er, leaving the pen and ink ~drawing. Figure 51 shows a print after it has been inked-in, Figure 7 showing the original print. Th·e result after using the reducer is seen in Figure 52, where only the line drawing remains. Cartoons from photographs are effec' tive for lantern slides and can easily be made Figure 51-Inked-in Print. in the same manner. Coloring. It is not the aim here to describe the p:~ocfss of coloring, as that would call for a book in itself, but rather to discuss those points affecting glossy prints which are to be colored. · Such prints are so much more effec;tive in giving a ·d efinite idea of the · appearance of goods such ·--. as candies, toys, ·h and-painted china, etc., that they are rapidly replacing the black and white prints formerly carried by salesmen. Color half-tones can of course be used when wanted in sufficient quantity to justify the expense, but often only a few prints are needed. Preparation. As colFigure 52 Line Drawing. oring should be very exact as to shade, it is important to have a suitable negative, one which has been made on a color s·e nsitive plate, •

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, I

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PHOTOGRAPHIC PRINTING

using a suitable filter. Since the colors used are transparent, the color of the print determines in part the color of the finished picture. For most commercial subjects, a good black and white print is most suitable for coloring. However, many cases will arise where sepia-toned prints wilQ more faithfully reproduce the colors of the original. Some times printing-out papers may best serve the purpose, and there may even arise conditions where platinum-toned prints will form the best base for coloring. In other words, the printing process used should be one which best represents the predominating colors of the subject. Prints should not be squeegeed before the color is applied. 路Prints hardened in the regular acid fixing bath often refuse to take the color in spots. Washing the print for a minute or two in a 1% solution of ammonia water, will soften the emulsion slightly and remove any greasy finger marks. After this the prints should be rinsed and dried, or some of the colors may be affected by the ammonia. The prints may be slightly moistened again before coloring. It is better where glossy prints are made with the intention of later coloring them, to use the following fixing bath instead of the usual one as it leaves the Emulsion softer and' in bettter condition for coloring. Water

i g路al.

Hypo Sodium bisulphite

1 lb. 2 oz.

2 liters. 480 g. 60 g.

Afterward when applying colors, blot each portion after it takes the color to the desired depth. The application of saliva to the surface seems to make the colors take hold better. Dye-P1路oofing.-If letters or other small portions are wanted a pure white, a process known as dye-proofing may be resorted to. Protect the parts to be left white with dye-proofing liquid, applied with a pen or

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fine brush. When dry the color may be applied over the entire print. The dye-proofing may now be removed by rubbing with a cloth moistened with benzine, and those portions which have been covered with it be found to be a pure white. If desired, another color may be washed over the letters. This same solution may be used for covering certain portions of a print to be retained in black and white, while the remainder is to be redeveloped to a sepia tone. After-treatment of Colored Prints.-After using water colors, the print must be soaked in water to softm it before ferrotyping. This is liable to cause some of the colors to run. To prevent this, the print is sometimes placed in a 5% bath of phospho-tungstic acid until limp, just before ferrotyping. Perhaps a better method is to immerse the prints after being colqred and dried, in white vinegar for a few seconds, keeping them in motion to remove any free color. Sponge off the surface to remove dirt, rinse, and squeegee. Rapid drying seems to be beneficial.

will

Blue Prints.-(Cyanotype Process). 3 Many amateurs receive their introduction to printing thru making their first prints by the simplest and easiest of processes-blue printing. The commercial photographer is often called upon to make blue prints of architects' plans and engineers' drawings. Blue print paper is used for this purpose not only because the process is rapid and the paper inexpensive, but most important of a11, the lines printed from a drawing which takes the place of the negative, show up pure white on a deep blue field, thus making them easily read. Blue print paper may be secured ready prepared but as it does not keep very well and the average photographer has use for it only occasionally, he may prefer to prepare it himself. (See Experiment 25.) There Sfiaill:

Blue Printing and Modern Plan Copying.

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PHOTOGRAPHIC PRINTING

are many variations in the sensitizing formulae given, but the following is a good one: A

Water Ferric ammonium citrate (green)

5 oz. 1 oz.

150 c.c. 28 g.

5 oz. t oz.

150 c.c. 22.4 g.

Water Potassium ferricyamde

Take equal parts, preparing the mixture in the darkroom or in a feeble white light. Filter and use for coating the paper at once. Any good drawing paper is suitable, altho if it is desired to use it for prints, a sized paper will be smoother and show more detail. Place the sheet to be coated on a piece of glass or other level surface. Use a large, fiat, soft brush or soft sponge, dipping it in the solution and going over the paper rapidly, :first crosswise and then lengthwise, to secure an even coating before the liquid has a chance to sink in. The paper should then be hung up to dry, when it will be of a yellowish color. It should be used within a day or two. Print by exposing to sunlight, or use the arc or mercury vapor light. The time can best be determined by trial, exposing until the image appears and the print becomes a dirty-looking bluish-brown color. Develop by washing until the water remains clear, then hang up to dry. A better blue is generally obtained by printing a little deeper than usual and then adding enough potassium bicromate to the wash water to give it a slight yellow tint. Chemistry of Blue Printing.-Ferric ammonium citrate is the light sensitive substance, 1being reduced by the light to the ferrous state. When the paper is placed in water, the ferrous salts react with the potassium ferricyanide where they have not already done so, resulting in the formation of Turnbull's blue, a deep blue insoluble compound, Fe,[Fe(CN) 6 ] 2 â&#x20AC;˘ Where the paper has not been exposed, the ferric salts not reacting with

the potassium terricyanide are washed out, leaving white paper.

CHAPTER XIX. PRINTING ON GLASS.

Only those printing processes have been considered thus far which have to do with the making of positive images on a paper base. Those described in this chapter, while perhaps of less importance to the average photographer, are nevertheless full of interest and at times may be found most desirable. Some of the most beautiful pictures are those made on glass or other transparent support. Possibly pictures of this kind would find favor over all others if it were not for the greater inconvenience in storing and viewing them. Those in most general use are lantern slides, transparencies, and doretypes. LANTERN SLIDES.

A lantern slide is nothing more or less than a positive print on glass. Instead of the customary printing paper, a special plate is substituted and the negative printed on it. A lantern slide, being a transparency, is viewed by transmitted light and not by reflected light like a print. Size.-Slides are made small and viewed by being thrown upon a large screen by means of a projection lantern. Since these machines are standardized as to the size of slide they will take, it is necessary that the worker make slides of standard size. In England, this is 3!-x,ff~ while in America it is 3lx4.". However, these sizes may be used interchangeably. Use.-With the ever-increasing popularity of motion pictures, it might seem that the day of still pic-

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PHOTOGRAPHIC PRINTING

tures is past. This does not prove to be the case, however, as the use of lantern slides is rather on the increase. Not only are they widely used for advertising purposes m connection with motion picture programs, but they are also much used for illustrated lectures both on the platform and in the school room, where they are coming to be considered indispensable. In college classes they are of the utmost value as an aid in instruction along scientific and other lines, where an enlarged image of the object must be seen by all of a large class at one time. Methods.i-Lantern slides may be made by enlargement from a small portion of a negative, reduction from a larger negative, or by contact printing. The first two methods are very similar to ordinary enlarging or reduction on bromide paper, except that a suitable plate is used instead of paper, and more often some form of camera with plate holders for the lantern slide plates is used. The negative should be one that in so far as possible is technically perfect. As all defects are greatly enlarged on the screen, it is very important that the negative from which a slide is to be made, be free from pinholes, scratches, stains, and other blemishes. A good snappy negative is necessary, one that has been fully exposed and correctly developed. However, it must not be too contrasty or the slide will be blocked in the shadows, lacking luminosity and detail. Lantern slide plates are available in fast and slow grades, and in various degrees of contrast. For contact work, the slower grades are preferable as they have a finer grain which shows detail better when enlarged. Correct exposure is also more easily obtained. IPhoto-Miniature No. 130: How to Make Lantern Slides. Fr81Prie (Ed.): How to M!ake Lanum Slides.

l>RINTING ON GLASS

245

Exposure is usually made in an ordinary printing frame or better in a lantern slide frame, a short distance from a weak light source. The negative is placed in the frame and the plate laid on it so that the two emulsiQns are in contact, care being taken that all dust is carefully removed with a soft camel's hair brush. If many slides are to be turned out, a printing machine can easily be improvised that will save much time and labor. The printing box should be about 6 inches square and 3 feet deep with a 10-watt white light and a small ruby 路light at the bottom. A miniature printing machine top, that will automatically turn on the white light when pressed down for printing, will be a valuable addition. At a distance of 3 feet from a 10-watt bulb, exposure will vary perhaps from 3 to 15 seconds, depending on the density of the negative and the speed of the plate. Development must take place in a suitable light, one of a deep orange color being safe for most plates. Hydrochinon is perhaps as good a developing agent as any, altho amidol will be found a very close rival. Hydrochinon works rapidly, gives a fine grain, good contrast, and pure blacks. A slide rather blue-black in tone is usually considered better than one with greater warmth. Below is given a typical hydrochinon formula for lantern slides and other transparencies. 2 However, the formula given by the manufacturer should usually be followed. Water Hydrochinon Sodium sulphite (powdered) Potassium bromide Citric acid Sodium carbonate (powdered) 2See Cramer's Manual.

20 oz. 60 gr. 120 gr. 6 gr. 6 gr. 1 oz.

1600 c.c. 10 g. 20 g. 1 g. 1 g. 80 g.

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PHOTOGRAPHIC PRINTING

It is important that the temperature of the developer remain about 65°F. (18.3°C.) as any decrease quickly affects the energy of hydrochinon developers. Use a white tray and develop the slide until the image appears a little too dark for a good print as it lies in the bottom of the tray. The highlights must be very transparent, in fact almost pure glass, while the shadows should be full of detail and not too dense. If exposure has been insufficient, the image will app(~ar slowly and have considerable contrast but refuse to gain sufficient density. If overexposed, it will quickly flash up and the highlights soon veil over. The color will be slightly brown and the slide appear muddy.

Fixation.-After developing, rinse for an instant and fix in the acid fixing bath described in Chapter XI, or preferably. in the following one: 3 A WaterHypo

B Water Sodium' sulphite (powdered) Sulphuric acid, C. P. Chrome alum (powdered)

128 oz. 32 oz. 32 oz. 3 oz. ~ oz. 2 oz.

4 liters 1 ·kilogram 1 90 15 60

liter g. c.c. g.

Mix in the order given, pouring (B) into (A) while stirring. In cold weather one-half of solution (B) may be sufficient for the amount of (A) given, as there is then little danger of excessive softening of the emulsion. To insure the thoro removal of the silver bromide from the slide, it should be left in the fixing bath at least twice as long as it takes to clear it, as by the time the milkiness has disappeared, only the insoluble silver sodium thiosulphate has been formed. Giving double this time wil1 result in the insoluble form being conssee Cramer's Manual.

PRINTING ON GLASS

247

verted to the soluble kind which may then be removed by washing. This should be carried on for at least 15 minutes-a half hour is better. Slides, like negatives, may be intensified if too thin or reduced if too dense. Slides in Colors.-While a good clear black and white slide is all that is desired for most work, still there are many subjects that show up best in colors. It is possible to obtain a certain warmth of tone by direct development with a suitably modified developer but the result is at best but mediocre. A great variety of tones and combinations of colors are available by the several methods of toning and coloring. Hand coloring, using water colors, is easily learned and givâ&#x201A;Źs beautiful effects when properly done. Slides should be thin but full of detail. Care must be taken that the colors do not overlap and that the coloring is not overdone. Tinting or the immersion of the slide in a weak solution of a water-color or dye gives a uniform tint over the entire slide and is very good for moonlight and similar effects. Toning, as distinct from tinting, results in the image being colored, thus permitting the highlights to remain clear. Perhaps the easiest method of toning is by replacing part or all of the silver comprising the image with some other metal or compound of a different color. For example, replacing the silver with silver sulphide results in a brown image. The redevelopment, bluetoning, and chalk-red toning processes given in Chapter XIV will be found to work well on slides. Mordanting or Dye-Toningâ&#x20AC;˘ is one of the processes more recently coming into use. Here the image is converted into some salt which has an absorbent action on basic dyes. The image is first converted to copper â&#x20AC;˘Lantern Slides-How to Make and Color Them. (Eastman Kodak Company).

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PHOTOGRAPHIC PRINTING

ferrocyanide or other inorganic compounds which have the property of mordanting or causing certain dyes to adhere when immersed in them. In addition to these methods, there are many others5, such as the use of autochrome plates which give slides in natural colors, and the carbon process and its variations. Titles.-Slides for advertising purposes, lectures, etc., are often required with reading matter. A convenient method of preparation is to have this printed in white on a black card, properly arranged to occupy the desired portion of the slide. Copy this on a contrast slide and use instead of the regular cover glass. Mounting.-Before mounting, it is well to protect the slide from dampness by coating with a good negative or lantern slide varnish. The negative should first be heated sufficiently to drive out any moisture. The first step in mounting is to mask off undesirable parts of the image. For this purpose, masks may be secured in a variety of shapes and sizes but it is questionable if any form is as satisfactory as a plain rectangle, nearly full size. If preferred, the openings may be cut from special masks, or the slide can be blocked out to the proper size with opaque and ruling pen. After masking, a white spot or thumb mark should be placed in the corner that is at the lower left when the slide is held as it should appear on the screen. This serves as a guide to the operator when inserting the slide in the projection lantern. Since the finished slide would soon become scratched. dirty, and covered with finger marks, it must be protected. Special cover glass may be used, tho spoiled slides with the emulsion removed will be equally satis5WaB:

Practical Color Photography.

PRINTING ON GLASS

249

factory. Binding the cover glass in contact with the emulsion of the slide with binding strips or similar material cut to correct length, completes the operation. TRANSPARENCIES.

By transparencies are meant pictures made on glass or other transparent support, which are suitable for viewing by transmitted light. They are beautiful, being much more luminous than pictures that are seen only by reflected light. Their preparation is similar to that of lantern slides, except that they should have slightly more density, especially in the highlights. By the aid of the enlarging camera, they may be made any size. Slow, rather contrasty emulsions are most suitable in the majority of cases. Mounting.-ln order that the eye may look at the image and not thru it, a piece of fine ground glass should be bound in contact with the emulsion side of the transparency. This also serves as a protection similar to that accorded by the cover glass on slides. Transparencies are perhaps most used for home decoration. There are several kinds of frames on the market which make it convenient to hang them in windows or in front of other suitable light sources. Sometimes, they are used to make up shades for electric table lamps. Special viewing cases are also available with mirrors to reflect the light thru the transparency. Commercially, they are used quite extensively in the advertising field. OPALS.

Opals are simply white opal matte-surface glass coated with a transparency emulsion. Their manipulation is similar to that of lantern slides. When

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PHOTOGRAPHIC PRINTING

used for portraiture for which they are perhaps most suitable, they should preferably be redeveloped and hand colored with water colors. However, they may be toned by the use of any of the processes mentioned, except by the use of warm baths. They are best finished by coating with a good negative varnish, covering with glass, and then mounting in suitable frames. DO RETYPES.

If properly made, a doretype is one of the finest of photographic productions. It differs from the other transparencies in that the picture is visible largely from the light reflected by the material used as a backing for the positive. Using a lantern slide or transparency plate, make a very thin positive, so thin that it might seem at first sight to be worthless. A metol-hydrochinon developer such as is used for prints is usually better than a straight hydrochinon developer, since excessive contrast is not wanted. This positive should be of such contrast and density that when placed emulsion side down on a piece of white paper, the picture will be visible in all the desired brilliancy. If the image is too thin, the highlights wil1 be an expanse of flat color; if too dense, the shadows will be black or brown and lacking in detail. Portraits should be made lantern slide size and, after being redeveloped and hand colored, be mounted in especially made doretype cases of soft leather. (See Figu1路e 53.) A most pleasing effect is secured by backing the plate with two or more thicknesses of silk. By experimenting with various combinations of shades, using one over another, a picture may be secured that will very nearly reproduce flesh tones. The silk, backed by a card, is placed in contact with the emulsion, enough cotton being put behind this to exert some

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PRINTING ON GLASS

pressure when the positive is fastened in the doretype case, thus giving good contact.

•

By courtesy of 7'aprell, Loomi1 &: Oo.

Figure 63

Dorety.p e. •

Or instead of the silk, the positive may be backed with bronze powder, a method which is preferred by many. For this purpose a light gold "Photo Coating Powder" is mixed with lantern slide varnish or other solvent to the consistency of thin cream and flowed over the emulsion side of the plate. It- is important that the plate lie flat while drying so that it will not become streaked. This may take half an hour. For views, the positive had better be left in black and white and then coated with aluminum "Photo Coating Powder", similar to the gold. A great many varied effects may be obtained by the use of brightly polished steel, colored pape1·, and other materials for backing.

CHAPTER XX. PRINTING-OUT PROCESSES. In addition to the processes already described, which are most commonly used because they are capable of producing good clear-cut pictures with a minimum of expense and effort, there are others which possess characteristics that make them even more valuable for special effects. These are processes where the image in most cases is made visible by exposure and is then toned and fixed. While ordinary printingout papers have been largely superseded in the studio by developing papers because the modem photographer believes he has not the time to spare for daylight printing, yet some of these papers are capable of producing results not excelled by any modem developing papers. SILVER PRINTING-OUT PAPERS.

Silver P. 0. P.-Under this classification are placed those silver papers as collodio-chloride and gelatinochloride already described in Chapter VII. Aristo and Solio are examples of these papers that have been very extensively used in the past. Papers of this type seem to be coming into use again and should be acceptable to those who have time for their manipulation. Printing is usually done by daylight, but bright sunlight is not as suitable as more diffused light since it seems to give flatter results. The depth to which printing should be carried depends on the brand of paper used and the kind of toning bath, as well as the effect desired. The print should be examined from time to time in a subdued light by opening one end of

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the printing frame. When it is seen that the highlights have a decided tint and that the shadows are beginning to block up, the print should be removed. As a decided bleaching action takes place during toning and fixing, the print should be made considerably darku than the finished picture is wanted. Toning.-Since these printing-out papers contain an excess of silver nitrate over the sodium chloride, the excess silver prevents their being developed except by special manipulation, as otherwise fog would result. However, if merely fixed after exposure, the disagreeable red color would be very unsatisfactory, so in order to secure a better color, the prints are often toned in a gold or platinum bath, or in both if desired. Before toning with the gold solution, the print should be washed in several changes of water to free it from as much of the silver nitrate as possible. Otherwise this may be precipitated as silver chloride by the action of the gold. Some of the silver image, too, is likely to be changed into silver chloride, but if any of this is formed, it is later dissolved by the hypo. AuC1 3

gold ch1oride

3Ag = Au silver

gold

3AgCl silver chloride

The resulting tone of the print is due to several causes, among which are the size of the gold particles deposited (the coarser ones giving a bluish color), and the relative mixture of silver and gold of which the image is composed. Printing-out papers of different brands are of such variable composition that no formula can be given which will be satisfactory for all. The one recommended by the manufacturer should be used. A simple bath that works well on some papers is: Water Gold chloride

30 oz. 1 gr.

1. liter .07 g.

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PHOTOGRAPHIC PRINTING

Just sufficient borax should be added to make the solution slightly alkaline. This seems to cause more rapid deposition of the gold with more of a blue tone. Toning should be stopped when the desired color is reached. For variety this may be followed by a platinum bath, some of the gold being there replaced by metallic platinum. Platinum路 baths are used in an acid condition. Prints after being well rinsed should be transferred to a weak fixing bath, using two or three ounces of hypo to a pint of water (60 to 80 g. per 500 c.c.). Combined toning and fixing baths are sometimes used but there is considerable doubt as to the permanency of prints toned in this manner. Self Toning Papet"S are made by most manufacturers of other printing-out papers. They have the necessary gold or other toning salts incorporated in the emulsion, and need only to be washed and fixed. A colder tone may be obtained by immersing for a few minutes in a 10% salt bath before fixing. These papers require only the simplest manipulation and produce first class results. PICTORIAL PRINTING PROCESSES.

For pictorial representation certain printing-out mediums are unexcelled, .never having been equalled by the more rapid developing papers. Here it is desired to reproduce the subject, not necessarily as the eye sees it. but rather as the ideal which the worker has in mind. Such mediums are more susceptible to modification in printing and development or other manipulations than chloride and bromide papers. By their use, the worker can make not merely photographs but rather pictures, which like paintings produce a feeling or mood in the observer.

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No attempt is made to give more than a brief idea of the working of these processes and the principles upon which they are based. Those who desire to know more of the actual manipulations are referred to the many works on the subjeet. 1 â&#x20AC;˘ Platinotype or Platinum Printing.--To the eye trained to see beauty, there is nothing more satisfactory than a good platinum print. Here is seen a picture in exquisitely graduated tones of black and white or sepia, giving an atmospheric effect of depth not easily produced in other mediums. Not only is the result most beautiful, but as the image consists of finely divided metallic platinum on a pure paper base, its permanency is unquestioned. For these reasons, platinum is the medium largely used by pictoralists as well as by firms who make reproductions of famous paintings and works of art for libraries and other public institutions. As no substratum is necessary for the image, variation in the surface of the paper base will be reflected in the picture. Since platinum is much more expensive than gold, there is a tendency to use too little of the platinum salt in the manufacture of the paper to produce the best results. Other metals as palladium are often used in place of platinum, or a mixture of platinum and silver salts may be used. This combination will produce pleasing pictures but the process is m1,1ch more tedious. Manipulation.-The paper is exposed by daylight or strong artificial light until all parts are visible except the highest lights. At this stage it will look some'Anrler1=;on: Pictot-ial Photography. PltQto-Miniature No. 115: Platinum Printing. Photo-Miniature No. 86: Carbon Printing. (Autotype Co.): ABC Guide to (;arbon Printing, Wall; C"rllon Printing,

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thing like a blue print or a bleached bromide print. The paper must be protected from moisture both before and after printing. The print is then placed in the following devcloper2 , taking care that it is immersed quickly and evenly: Potassium oxalate Water (hot)

A (Stock solution) 6 oz. 20 oz.

Let stand for a day or two to clear. Solution (A) Water Oxaolic acid (saturated solution)

180 g. 600 c.c.

For use, take

oz. oz. 1 oz.

195 c.c. 420 c.c. 30 c.c.

This should be used at a temperature of 70° to 120°F. (21 ° to 48°C.). Development seems to be complete at once but should be allowed to continue from half to a full minute. If not worn out the developer may be preserved for future use. The print is now placed for 5 minutes in a clearing bath of hydrochloric acid (specific gravity 1.16), using 1 part to 60 parts of water, and then transferred to similar baths for 10, 15, and 5 minutes, respectively. When the fourth bath becomes discolored discard it, making up a fresh No.1 bath and movins:r over the othfrs. Washing for half an hour completes the process. There are of course many modifications possible. Chemical Action.-Platinum paper is coated with ferric oxa1ate and potassium chloroplatinite. The light reduces the ferric oxalate to ferrous oxalate. Fe2 (C 2 0 4 ).{ ferric · oxalate

light

2FeC 2 0 4 ferrous oxalate

+ 2C0

carbon dioxide

The ferrous ·oxalate formed here is practically insoluble except in a solution of potassium oxalate, which is supplied by the 2Photo-Miniature No. 116:

Platinum Printing.

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developer. Where the light has acted, the ferrous oxalate is formed and as soon as dissolved, immediately reacts with the platinum salt--chloroplatinite. 3K}>tel 4 +6FeC 2 0 4 Chloro- ferrous platinite oxalate

3pt+2Fe2 (C 20 4路) 3 +2FeCl .. +6KCl platinum ferric ferric ~ potassium oxalate chloride chloride

The ferric and other salts are dissolved out hy the dilute路 hydrochloric acid and by washing, thus leaving the metallic platinum image.

Ca1路bon Printing.-For the worker who desires to express his individuality in the making of pictures, the carbon process will be found equal if not superior to platinum and other mediums. Carbon is easy of modi; fication in development and is among the most permanent of papers. Not only do the prints_ have a real richness and depth of tone, but they. can be made in forty or more shades and colors, a variety which is not offered by any other regular printing process. The principal disadvantages of carbon are that it is a slow printing paper like platinum, the image is not visible when printed, and it must be transferred bP.fore development. The carbon process is based upon an entirely different principle from any of the printing methods already described. Carbon tissue3 is not a thin tissuelike paper as the name implies but a heavy paper coated with gelatine, which is itself the light sensitive material. As the clear gelatine would provide no contrast, a very finely ground pigment is incorporated in it. Upon the color of this pigment depends the final color of the print. Before using, the gelatine surface is sensitized with a solution of potassium bichromate. If this bi3 Manufactured by the Autotype Co.mpany, London, England. American Representative: Geo. Murphy, Inc., New Yorl!; Cit1 . 路

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chromated路 gelatine is now exposed under a negative to light, it will be rendered insoluble in warm water in proportion to the amount of light received. However, all the surface of the paper will receive some light and to that extent be rendered insoluble, while the gelatine underneath, not receiving light, can be washed away leaving the image-. This consists of varying thicknesses of gelatine and color pigment. Due to the fact that it is the underlying strata nearest the paper base that remains most soluble, immersion in warm water will dissolve that portion leaving the. image more or less without a support. Therefore it is necessary to transfer the gelatine to another support of paper, glass, or other material where it is developed. No developing or fixing chemicals are required. M ethod.-Since the tissue is inclined to become in. soluble if kept for some time, it is better to sensitize it just before using. For this purpose a 3% solution of potassium bichromate is most commonly used. If a sensitizing solution is desired that will keep for some 路 time, add one-fourth as much citric acid as of the bichromate salt used, and just enough .ammonia to change the color from orange to yellow. Allow it to stand until the ammonia passes off, before using. The prints should be immersed for about 2-! minutes at a temperature of 65掳F. (18掳C.). Longer immersion in a stronger bath gives a faster printing paper with lessened contrast. The bichromate may be varied from 1% to 7%. If a quick drying sensitizer is needed, alcohol may be used to take the place of part of the water. After removing from the sensitizing bath, lay the paper face down on a piece of glass or a ferrotype plate and using a flat rubber squeegee, remove the excess moisture by rubbing lightly. When dry the paper is ready for printing. The sensitizing and drying must take place in a safe or subdued light. Exposure is usually made by daylight, using an

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actinometer, which is a kind of exposure meter, to determine when printing has been sufficient. Instead of this, a proof may be printed at the same time on P. 0. P., the printing time of carbon being very similar. As the print will be reversed as to right and left when transferred, it is necessary either to use film negatives and then print thru the back, or to transfer the image twice. The latter method is not to be recommended as a general thing, as it takes a much longer time and the chances of failure are greatly increased. When printing, the edge of the paper should be protected from the light, thus leaving it in a soluble condition so that the image itself will not be so liable to leave the transfer paper when developing, and instead stick to the original backing. The print should be developed soon after exposure. as the light action continues. While the print is being exposed, a sheet of transfer paper should be placed in water to swell the gelatine. Soaking for fifteen minutes or longer will do no harm. This transfer paper is simply a suitable paper, coated with insoluble gelatine, which may be obtained ready for use or be prepared by the worker. After exposure, place the tissue in a tray of water about 65째F. (18째C.). As soon us it begins to straighten out and bec<>.me limp, bring the transfer paper in contact with the tissue under water, lift out, drain for a few seconds, place on a smooth support with the tissue uppermost, and squeegee in cor:ts.ct. The sheets are now placed between blotters under a few pounds pressure for twenty minutes to half an hour. Now place the transfer paper and its adherent tissue in the developer which is a tray of plain water at a temperature of 95째F. (35째C.). In a minute or two the pigment will begin to ooze out from the edges of the tissue. As soon as this occurs, gently remove the

260

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tissue backing and discard it. The image is now on the transfer paper but is barely visible until the soluble parts are washed away. This may be done by placing the print on a piece of glass held at an angle, and with a cup or the hand dipping water out of the tray on to it. If overexposed use warmer water, up to 120째F. ( 48째C.). Local development may be affected by pouring warm water on the pol'tions it is desired to lighten. The image must not be touched by the fingers or other objects until dry. After development is complete, place the print for five minutes in a 5% solution of powdered alum. This removes the bichromate stain and hardens the gelatine. Rinse in three changes of water and place face up on blotters, or hang up to dry. Prints for transparencies may be developed directly on opal glass or on plain glass coated with insoluble gelatine. In case glass plates are used for negatives, and the picture is not wanted reversed, the double transfer process must be resorted to. The image is developed on a suitable temporary support, washed and dried, and then transferred to a final support which may be paper, ivory, or any other suitable material. Carbro Printing Proeess!-This is a modification of the carbon process. It has the advantage that carbon prints of any size may be made without exposure to light. A good bromide print made either by contact or enlarging is used as a basis for the process. A piece of carbon tissue is immersed in a bath of potassium bichromate, potassium ferricyanide, and potassium bromide for a few minutes. Then it is place.d for a few seconds in a bath of glacial acetic acid, hy4For working instructions see directions of Autoty:pe Co., London,

PRINTING-OUT PROCESSES

261

drochloric acid, and formaldehyde. It is now brought in contact with the bromide print (which has previously been well soaked in water), squeegeed in contact, and left for a short time. The pigmented tissue is now removed from the bromide print and squeegeed in contact with the transfer paper. From this point on, the process is similar to regular carbon printing. 路The bromide print which has become bleached by the process is washed and developed, then washed again and is ready for making other prints, or it may be dried and preserved. Other Ptinting Mediums.-The two pictorial mediums already discussed-platinum and carbon with its modification in the carbro process-are the ones most likely to be used by the average worker. This being the case, mere mention need be made of the others which are of interest only to the advanced pictorialist. While they are based upon photography, yet after all. their success is more dependent upon technical 路 skill and powers of artistic expression than upon chemical or physical reactions. These processes give the worker almost unlimited opportunity to secure any desired effect thru variety of paper stock, modification of tonal contrast, and the use of pigment and oil. Duplication of any given result, however, is not easy. Among the most widely used of these mediums are gum with its various modifications-multiple gum, gum platinum and gum bromide; and oil with its variations--bromoil and bromoil transfer. Gum Printings, or gum-bichromate as it is often called, is based upon much the same principles as carbon and might almost be considered a variation of that process. A mixture of finely . ground pigment, gum 5

Anderson: Pictorial Photography.

262

PHOTOGRAPHIC PRINTING

arabic, and a little potassium bichromate is coated up.. on a fairly rough paper support. exposure to the light, the bichromate salt is decomposed and acting on the gum arabic, renders it insoluble in water proportional to the amount of light action. Development takes place by immersing face down in cold water and may r€quire an hour or more. The process differs from carbon in that gum arabic is the colioid used instead of gelatine, that cold water is used for developm€nt instead of hot, and thal development takes place from the front. Also the roughness of the paper support increases the scale 'Jf gradation in gum prints. In order to get a full range of tones and ri(;her shadows, multiple gum is often resorted to. This consists of repeated applications, exposure, and develop.. ment of the coatings of gum and pigment until the shadows are of sufficient depth. The final result may be considerably altered by using different colored pigments for the different printings. As a means of securing the richness of the multiple gum print and the gradations in the highlights of platinum, a platinum print may be used as the foundation image, the gum pigment coating being placed over it. Then by a single exposure, a gum-platinu·m. print, as good or better than a multiple gum print, is secured, and without sacrificing the peculiar quality of the gum print. When a bromide print is used as the foundation, the result is known as a gum-bromide print.

Oil Printing differs considerably from the processfs just described. A suitable paper is given a thin coating of unhardened gelatine. When dry, it is sensitiz€dby immersion in a solutionof a potassium or other bichromate salt. Printing is carried on in the sunlight or other strong light and should continue until a

PRINTING-OUT PROCESSES

268

tint is visible in the highlights. The print is now pJaced in plain water until all trace of the bichromate stain has disappeared. The highlights that have been unaffected by the light absorb water and become inflated, while the shadows that were acted upon by the iight become tanned in proportion to the amount of light action and do not take up water, appearing as depressions on the surface. The print is now placed upon a pad of wet blotting paper and pigmented or inked. This is done by dabbing on tQ.e ink, which may be a stiff lithographic ink or suitable pigment, withspeciallypreparedbrushes. The portions that have absorbed the greatest amount of water, i. e., the highlights, will repel the pigment more than those portions which have been more fully exposed and have not absorbed so mYch water. It is readily seen that by suitable manipulation with the brushes, there are almost unlimited possibilities in the control of the relative values. Bromoil Prints 6 are simply bromide prints which are pigmented after the silver image has first been bleached out. The bleaching is usually done in a bath of copper sulphate, potassium bromide, potassium bichromate, and hydrochloric acid, altho other bleachers are used. This bleaches the silver image and tans the gelatine in proportion to the amount of silver in the image. The print is now fixed, washed, and pigmented or oiled as in the process just described. The tendency to repel water and attract the oil is in proportion to the amount of tanning. Naturally the color of the print will depend upon the pigment, more than one color being used if desired. Oil and Bromoil Transfer.-If the freshly inked oil or bromoil print is placed in contact with a sheet 6 Photo-Miniature No. 186: Transfers.

Bromoil Prints and Bromoil

264

PHOTOGRAPHIC PRINTING

of drawing paper or other similar paper, and the two run thru a roller press or clothes wringer, most of the oil will be transferred to the uncoated paper, giving .1;\ result resembling a lithograph. A number of transfers may be made from a single print by re-inking.

CHAPTER XXI. PRINTING IN COLORS.

When admiring the grandeur of a mountain view or the sublime beauty of an evening sunset, who has not wished for some means of recording these colors in all their tints and naturalness? Pictures in monochrome, while quite faithfully translating color values into shades of black and white and answering all oz路dinary requirements, are yet most unsatisfactory for depicting those scenes or objects involving color. Photographic means of reproduction in color have been attained, and while color photography has not yet been accorded any very high recognition by students of art, it is already considered a valuable aid to the scientist, especially the biologist and the physician. Innumerable processes and variations of existing processes have been brought forward from time to time, and a great number of patents have been granted for photographic color processes. However, no method has yet been devised for making pictures in colors that even remotely approaches the simplicity of ordinary black and white photography. They are too complicated to enable one to turn out a large number of uniform pictures in a short space of time with a minimum of effort, knowledge, and expense. Only a brief review of some of the more practical processes can be given here as detailed description and working directions would be entirely beyond the scope of a single chapter. 1 tit is suggested that those who are interested in trying out color printing procure a copy of Practical Color Photogro,phy by E. J. Wall. Much valuaJble information may a:lso be secured in the Monthly Supplements on Color Photography issued in connection with the British Journal of Photography.路

266

PHOTOGRAPHIC PRINTING

Color.-The color of any object is not a :fixed property as many people suppose. If the object is viewed in a blue, yello~, or other colored light, it will be noticed that the colors seem vastly different than when seen in white light. The different materials of a colored object absorb certain wave lengths of Jight and reflect others. The ones reflected to the eye are the ones that make up the color of the object as we know it. Scientific research has led toward the belief that the eye sees color by means of only three distinct sets of nerves, one set being capable of distinguishing red, another green, and another blue-violet light. By the combination of the impressions on these three sets of nerves are produced all the sensations of color which can be perceived. Whether this is true or not, it is nevertheless easily demonstrated that by the combination of these three colors, any color. or white light, which is composed of all colors, may be produced. The composition of a beam of white light can be determined by passing it thru a prism where it will be broken up into a series of tints, ranging all the way from red at one end thru orange, yellow, green, and blue, to violet at the other. According to the most ~idely accepted theory, light is transmitted by an extremely short and rapid vibratory motion in the ether, the wave lengths being longest at the red end of the spectrum and shortest at the violet end. Beyond the visible violet end lie even shorter wave lengths which make up the ultra-violet light which is very active photographically. Color Photography.-Practically all the processes of color photography are based on the theory of color already mentioned-that from red, green, and blueviolet light can be formed any possible color combination. The majority of workable processes perhaps fall into two groups: (a) the making of color screen

PRINTING IN COLORS

267

transparencies that must be viewed by transmitted light; (b) the producing of color-separation negatives from which prints in color are. made. Screen Plate Processes.-The screen plate process has been adapted in a number of ways, two of the most succ:ssful resulting in the autochrome and the Paget plates. The autochrome introduced by Lumiere is perhap3 the simplest adaptation. It consists of a glass plate coated with a sticky varnish on which is dusted a mixture of fine starch grains which have been dyed the three primary colors and mixed together in suitable p:路oportion, resulting in a colorless coating. Over this is applied a water-proOf varnish and then a very thin panchromatic emulsion. In making the picture, the exposure is made as in the case of the ordinary plate except that the glass side is toward the lens. By this means, the exposure is made thru the red, green, and blue-violet starch grains which act as filters. The exposed plate is dev::loped either for a definite time, or by inspection using a special green safelight. After rinsing, it is immersed in a reversing solution which will dissolve out the finely divided silve1路 forming the negative image and give clear places in proportion to the amount of silver deposit. When this deposit has been removed, the starch grains transmit light like that which came to them in the camera. The remainder of the silver salts, not affected by the primary exposure and development, are now reduced to metallic silver by amidol or other suitable developer. This development must take place while the plate is exposed to a strong white light so as to bring it to a developable condition. The reduced silver blocks out effectively those grains which did not transmit light in the camera, and so increases the brilliancy of the picture. Rinsing and varnishing complete the process unless intensification is neces-

268

PHOTOGRAPHIC PRINTING

sary. The plate is now ready for viewing either as a transparency or in the lante],"'l. The Paget plate differs from the autochrome in that the panchromatic emulsion and mosaic color screen are on separate pieces of glass. Exposure is made thru the screen which is placed over the plate in the holder. After the plate is developed, fixed, washed, and dried, a transparency is made which is bound exactly in register with a special viewing screen similar to the taking screen. Any number of duplicates may be made and bound with identical viewing screens. Color-Separation Negatives.-At the present time there is no three color camera available which is priced within the reach of the average worker. Such a camera2 should be capable of exposing three plates from the one lens so that by the aid of suitable filters and reflectors, each plate receives the light of one of the primary colors. Lacking such a camera, exposures may be made in succession on three panchromatic plates in an ordinary camera, using respectively orange-red, green, and blue-violet process filters. Proportionate exposures路 are given, depending on the plate and filter used. Sometimes it is more convenient to make an autochrome or similar color plate of the subject, and then to make the three color-separation negatives from this, using special tri-color filters. As panchromatic plates and films are very sensitive to light of any color, it is well to desensitize them in order that a brighter light may be used when developing without danger of fog. If the plate is placed in a preliminary bath of phenosafranin, an aniline dye, it may be placed in the developer and finished in a fairly bright yellow light. A stock solution of phe2

Wall:

Practical Color Photography, 51-53.

PRINTING IN COLORS

269

nosafranin, 1 to 2000, should be made up and used 1 part to 9 parts of water for the preliminary bath, or the stock solution may be added directly to the developer to the extent of about one-tenth of its volume. From the three finished negatives, positives may be made which are a reproduction of these primary light colors in terms of clearness. That is, the negative exposed thru the orange-red filter will show a deposit wherever light of that color is present. On the positive, this will appear as nearly clear glass depending on the depth of the color present in the original object. In the same way on the second positive; there will be relatively clear glass where green light was filtered thru, and on the third where blue-violet was transmitted. These positives may be viewed on the screen by means of the Ives' Triple Projection Lantern, using suitably colored lights or filters. Such methods of producing pictures by bringing together the colored images are known as additive methods. Color Printing.-For practically all color printing processes, the color-separation negatives just described are used. However, the method is not quite so simple as in the case of transparencies, for here, instead of reproducing the primary colors in terms of clearness, we have the problem of reproducing them thru pigments. Pigment colors, sometimes known as "minus" colors, are made up of the three primary colors, red, blue, and yellow. These must not be confused with the "plus" colors of light which breaks up into red-orange, green, and blue-violet. A piece of paper looks white because it reflects back to the eye all the various wave lengths of light, i. e., all the rays of light falling upon it. Any two or more colors which combine to form white light are said to be complementary. If the paper is coated with a yellow pigment. it will possess selective absorption,

270

PHOTOGRAPHIC PRINTING

subtracting some of the colored light rays and reflecting only the yellow. The ones absorbed are the ones complementary to the ones reflected-in this case the blue-violet rays. In the same way, red pigment on white paper reflects red, absorbing the green (which is a combination of blue and yellow, the other two primary colors); the blue pigment absorbs orange light (the mixture of red and yellow). If the three colored pigments are placed one over the other, they will absorb all the rays of light, thus forming black. Thus it is seen that in order to obtain a definite color on prints- it is necessary to coat the surface with a pigment which will take away from the white light the complementary color of the one desired. This process is therefore known as the subtractive process. In making the color prints, three negatives are made on panchromatic or color-sensitive plates using orange-red, grÂŁen, and blue-violet filters. If the negative made with the red filter were printed on a red pigment, those portions which contain a dense deposit caused by the action of light reflected from red in the object, would print clear and the shadow portions would be red, which is just the reverse of what is wanted. For in that case, the red objects in the original would show as white and all the rest of the picture which included no red would print red. The same thing would be true of the other two negatives if they were printed on paper pigmented with the color of the filter used. So instead, each negative must be printed in its complementary color. Iri order to accomplish this, the negative made with the orange-red filter must be printed in blue; the one made with the blue-violet, in yellow ; and with the green, in red. The colors in which they are printed may be of pigmented papers, colored inks, paints, or other coloring materials. The theory of the process is briefly this. As already stated, whatever red there may be in an object

PRINTING IN COLORS

271

will make a deposit on exposure to light, both on the negative where the orange-red filter is used and on the one where the blue-violet is used, as these both transmit more or less red light. When these are printed in the blue and yellow colors, respectively, thesJ deposits of the negatives will show up as nearly clear areas. In the third case, however, where the green filter is used, all the red of the light is held back by its complementary color, green, forming practically no impression of the red object on the negative. Therefore when this plate is printed in the red color, the red is unchanged wherever there was red in the original object. Then if these three colored prints are superimposed, the clear spaces on the first two will coincide with the red of the third, giving a red image in those spaces as the final result. In a corresponding manner, the yellow and blue colors are reproduced. When it is realized that all colors are made up of varying combinations of these three primary colors, and that each of the three filters is a complementary color of the primaries, it will be seen that all the colors of the original object will be accounted for in the final print. In order to have a representation that is at all accurate, however, the work must be carefully done, using process filters such as are employed in photomechanical work. Ordinary filters will not work accurately enough to correctly reproduce the colors. COLOR PRINTING METHODS.

A brief description will be given of some of the methods by which these underlying principles are carried out.

Three Color Carbon Prints.-Using the three color-separation negatives, three prints are made on "Trichrome Carbon Tissue". printing,,the red sensa-

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PHOTOGRAPHIC PRINTING

tion negative on the blue tissue, the green on the red tissue, and the blue on the yellow. These are developed on transparent temporary supports in the same manner as ordinary car:bon prints. When dry, 路the yellow print is transferred to its final support on white paper. Over this is placed the red print and then the blue one, each being cemented down in correct register. Perhaps a more convenient method is to use carbon tissue which can be obtained on thin celluloid supports. This is printed thru the back and developed on it..c; original support, making only one transfer necessary.. The Raydex Three-Color Process, which is also a carbon process, is much like the carbro process in that it relies on the reaction between the silver particles and the bichromate rather than on light action, to render insoluble the gelatine with which it is in contact. Three bromide prints are made under identical conditions, either by contact with the three color negatives or by enlargements from them. The three color tissue sheets, after being soaked in a special solution (presumably made up of bichromate and cupric sulphate, or bichromate, ferricyanide, and bromide), are squeegeed down on waxed supports. These are developed and superimposed on a final support just as in the carbon process.. Three Color Gum Process.-This is also somewhat similar to the carbon process. A gum print is made in the manner described in Chapter XX, using one of the color-separation negatives. After being washed, dried, and coated with a second sensitive mixture, containing another suitable pigment, it is printed from the second negative. Then it is recoated a third time, using the appropriate pigment, and printed from the third negative. Great care must be exercised to secure proper registration each time.

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273

The Pinatype Proeess.-From the three color negatives are made three transparencies or positives which by the latest methods are used as the "printplates". The positives are sensitized in an ammonium bichromate solution, dried, and路 exposed until details appear in the shadows. After removing the silver image, the print-plates are ready for staining in speci-al dyes, using colors complementary to the filters used. Each in turn is then squeegeed down to a plain gelatine-coated paper for a few minutes, a process which transfers the stain. The plates may be re-stained and used over many times. A Relief Process, similar to the pinatype process in that the final print is formed by the transfer of dyes, is worthy of notice. It is based on the fact that a suitable bichromate solution will cause the gelatine immediately surrounding each particle of silver to become insoluble in warm water. Three positives are made from the color negatives, preferably on films, printing thru the back. Otherwise the more delicate parts of the image may be washed away during subsequent treatment. After the positives are fixed and washed as usual, they are bleached in a potassium bichromate and hydrochloric acid solution. They are then immersed in warm water where the gelatine will gradually dissolve away, leaving a silver bromide image which is practically white. After this, the silver salts are removed by the use of hypo. The positives are then washed, stained, and printed as in the pinatype process. As only the gelatine image remains, and that only where there was a deposit of silver, there is nothing else to stain. Consequently a wider choice of dyes is possible than in many other cases, care being taken only that the proper colors are chosen.

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PHOTOGRAPHIC PRINTING

MOrdanting Processes.-Here the silver image is converted into silver or copper iodide or other salts which are capable of absorbing basic dyes. The bleached positives may be immersed in a dye solution that stains both the iodine compound and the gelatine but which readily washes out of the latter. The silver· iodide may .be removed in a hypo solution containing ·also sOme mordant as tannic acid to render the dye insoluble. Thus the silver image is replaced by a dye image, which, however, is embedded in the gelatine. Consequently the whole film must be transferred to a final support. -:-Three Color Photo;.Engraving.3-Altho not strictly a photographic process, color printing as a subtractive process has reached its highest industrial development in· the .illustrations in books and magazines, and in color reproductions of paintings and other works of art. The same three-color separation negatives are used as the··-basis for preparing three copper-etched 'blocks, whieh by the aid of suitably colored inks are used in printing presses to run off thousands of copies. Three separate printings are made in the course of the process, Hild in the hands of skilled workers give very beautiful results. · Cenelusion.-This brief explanation of some of the processes will perhaps open up to the studen:t ·some of the possibilities in color photography, at least as an avocation. There are, of course, a great many other processes available for those who are interested in delving deeper into this most interesting field of ph&tographic endeavor. s~ler

3 Raymer: Photo-Engraver's Hand-Book on Etching and Finishing.

APPENDIX

A-LABORATORY MANUAL Practical Experiments to be Performed in the Printing Room. The experiments as here given were originally designed for class work but are fully as applicable to the use of the photographer or amateur in his own printing room. Practically all of the chemicals and apparatus needed will be found in the average studio. The experiments have been planned to cover the general scope of the ordinary printing processes, a study peing made of the underlying principles upon which printing is based. ~he benefits of such experimentation are two-fold: (1) The student will gain practical information in regard to the various reactions, and consequently will have a more definite idea about what to do and not to do, to produce any desired results; (2) More important, he will learn something of the technique of experimentation, and will know better how to locate any difficulties and solve any problems which may arise, by following the same methods of careful observation of details. A study of the chapters indicated should be made before beginning an experiment so that a better understanding may be had of the problem at hand. If the laboratory work is to be of the most value, students should make accurate notes at the time, of the various conditions, reactions, and results. writing them up later in complete form so that they will have a permanent record which may be used for reference. Questions should be answered in full, and at the close of each record, general conclusions should be formulated. If time is limited, the following experiments will perhaps be of the most value: Experiments Nos. 1, 8, 9, 10, 15, 16, 17, 18, and 21.

LABORATORY MANUAL

27'7

CHEMICALS AND SOLUTIONS EXPERIMENT

No. 1.

Chemical Reactions. (Chapter IV.) i. Study of Silver Chloride.-Dissolve 10 grains of silver nitrate in 1 oz. of water, (1 g. in 45 c.c.); also 10 grains of sodium chloride in a similar quantity of water. (a) Slowly pour one into the other. Note effect. What is the cmnposition of 'the precipitate? (b) Add water. (c) Remove part of the precipitate and to it add a little hypo solution. (d) Place the remainder in strong light for a few路minutes. (e) Add developer. (f) Add hypo. State effect in each case. State general conclusion. 2. Neutralization.-Mix up ounce (30 c.c.) of a weak sodium carbonate solution; also a similar quantity of dilute acetic acid solution. (a) Test each with both red and blue litmus paper by placing a strip in each. Describe color of paper. (b) Pour a little of the acid into the carbonate solution. Describe visible effect and explain. (c) Continue adding the acid in small quantities, testing with the litmus paper each time until no further action is noted. In what condition is the solution now?

EXPERIMENT

No.2.

Oxidation. (Chapters IV and XI.) 1. Sodium Sulphite.-(a) Spread a small amount of powdered sodium sulphite on a paper and place it in a damp location for a few days. Is there any visible change? (b) Repeat, using crystals of sodium sulphite. (c) Mix a small quantity of developer, using a portion of the first sample for the preservative. What effect? (d) Dissolve the remainder of the first sample and test by adding a few drops of barium chloride solution. (A decided white precipitate insoluble in water and hydrochloric acid will indicate that a sulphate is

APPENDIX present). What is this sulphate? 2. Metol.~Dissolve 5 gr. (.3 g.) of metol in 10 oz. (300 c.c.) of water, and divide into two portions (1) and (2). (a) Add 15 gr. (1 g.) of sodium sulphite to No. 1, and then an equal amount of sodium carbonate. (b) Rej,eat with No.2, using carbonate only. Explain differences if any. EXPERIMENT

No.3.

Purification of Water. (Chapter V.) 路 1. :J.\Ilake tests for the following impurities in water as described in Chapter V: organic matter, calcium and magnesium, sulphates, and chlorides. State results. H O'W may these impurities be removed? 2. (a) Purify by distillation a small quantity of tap water. Note difference in taste. (b) Dissolve a small crystal of silver nitrate in a little tap water and another in a similar amount of the distilled water. What difference if any? Why? (c) Mix a small quantity of metol-hydrochinon developer, using the distilled water. Compare appearance with developer made with tap water. EXPERIMENT

No.4.

Preparation of Metol-Hydrochinon Developer. (Chapter XI.) 1. (a) Weigh out the metol and sulphite according to the regular formula for the developer. In mixing, first add about one-fourth of the sulphite, then all the metol, and then the remainder of the sulphite to .the water. Then add the other chemicals in the order given. Describe color of the solution. Why not dissolve all the metol or all the sulphite first'! (b) Divide the developer into two portions. Put one portion of the stock solution into a full corked bottle, and the other portion diluted one-half into an uncorked

LABORATORY MANUAL

279

bottle only partly full. Preserve for a week or more. Compare as to color and developing ability. What change has occurred? 2. Incorrect Method of Mixing.-(a) Using hot water, mix a small quantity of developer, letting it stand for several minutes after adding the metol before adding the sodium sulphite. What result? (b) Mix a similar quantity in the following order: water, metol, hydrochinon, carbonate, and sulphite. Note color of the solution. How may it be accounted for.? (e) Compare prints developed in a badly discolored developer with those developed in a normal developer. What is the function of sodium sulphite and how is it performed? No. 5. Acid Hypo Fixing Bath. Precautions. (Chapter XII.) 1. Mix the fixing bath by the regular formula. Note effect on the temperature of the solution by the dissolving of the hypo. Also note color and clearness of the solution after the hardener is added. 2. Improper methods. (a) Add a few drops of acetic or other acid to a small quantity of hypo solution. State result. (b) Add hardener to a small quantity of warm hypo solution before the hypo is all dissolved. Preserve for a few days and note results. What acids do and what do not decompose sodium thiosulphate? EXPERIMENT

No. 6. Preparation of Hypo-Alum Sepia Bath. Precautions. (Chapter XIV.) 1. Prepare sepia bath and ripener, using regular formulae. Divide sepia bath into two portions. (a) Add ripener to (1) according to regular method. Note color of bath. (b) Remove 1 pint (500 e.e.) of boiling sepia bath from portion (2) and add 1 dram (4 e.c.) of ripener. Note effect. (c) Repeat this as the EXPERIMENT

280

APPENDIX

bath cools to the following temperatures: 190°, 150°, 90°, and 70°F. (88°, 65°, 3~, 21 °C.) Note temperature at which bath does not discolor. (d) Sepia a few prints in the portion that turned darkest. What result? Preserve one print. EXPOSURE No.7. Testing Safelights. (Chapter III.) 1. Safelights may be tested by covering a portion of a strip of sensitive paper and exposing the remainder for 1 minute to the developing light at a distance of 2 feet. Develop the strip in regular developer. If no visible fog is produced the light may be considered safe. (a) Make tests of different safelights available, using slow chloride (contact) paper. (b) Repeat, using fast contact paper. (c) Repeat, using fast bromide (enlarging) paper. (d) If fog is not produced in the above cases, test to see how long the faster papers may be exposed to the light under the stated conditions. State results. What is a safelight? EXPERIMENT

No.8. Comparison of Short and Long Scale Papers. (Chapter VII.) 1. Make the following prints: (a) Long scale (contrast) negative on long scale (soft) paper. (b) Long scale (contrast) negative on short scale (contrast) paper. (c) Short scale (flat) negative on long scale paper. (d) Short scale (flat) negative on short scale paper. 2. Using a Test Screen Negative, make a print on each kind of paper. Print and develop so that two steps on one end are pure black and two or more on the other are pure white. Compare the number of visEXPERIMENT

LABORATORY MANUAL

281

ible steps, counting the numbers that are distinguishable. The softer paper will show the greater number of steps. P,reserve all six prints, properly labeling each. Tabulate results. Which prints are most nearly correct? 3. (a) Using the Test Screen Negative, compare the various brands of available portrait papers as to relative contrast. Tabulate results. (b) Or, compare commercial papers rated as hard, soft, etc. with those rated similarly by other manufacturers. Tabulate results. DEVELOPMENT No. 9. Variation of Potassium Bromide in the Developer. (Chapter XI.) 1. Provide three trays of normal paper developer: No. 1 with no potassium bromide added; No. 2 with t drop; and No.3 with 1-l drops of a saturated solution of potassium bromide per working ounce (30 c.c.). Select two brands of printing paper, one naturally giving a cold tone (i. e., containing a minimum of excess bromide in the emulsion) and the other normally giving a warm tone. (a) Make a print and develop in tray No.1. Note effect. (b) Make four prints from the same negative on each brand of paper, exposing in all cases so that development to the same depth is complete in exactly 1-! minutes.' Mark one lot (A) and the other (B). Develop two of each kind in tray No. 2 and two in tray No. 3. Preserve one print of each kind. Compare results as to color of black and white prints. 2. Sepia the remaining prints under identical conditions. Prese'rve prints. What difference in color is noted between the two types of papers? State general conclusions as to the effect of potassium bromide in the developer. EXPERIMENT

282

APPENDIX EXPERIMENT

J.-~'

No. 10.

Variation of Temperature of Developer. (Chapter XI.) 1. Make four prints from one negative on one grade of paper, developing two at 55° F. (13'' C.) and two at 75° F. (24° C.). Expose so that development will be completed to the same depth in 1-! minutes in each case. Sepia one developed at each temperature. Note difference in time of exposure, in contrast, and in color. 2. Using the same paper, give equal exposures to four prints from one negative. Develop to the same density, two at 55°F. (13°C.) and two at 75°F. (24°C.). Preserve one print of each. Note effect on time of ,ze'l.'elopment, contrMt, color, etc. • 3. Make prints from the Test Screen Negative at same temperatures. Compare as to contrast. If the temperatun~ (;_f the developer is lowered., is it better to increase tim,e c•f exposure or time of t~et•cl opment? Why? State general conclusions. EXPERIMENT

No. 11.

Use of Soft and Contrast Developers. (Chapter XL) 1. Prepare two trays of developer: one, soft-working, having the metol increased by one-half, and the hydrochinon and ca1·bonate decreased by the same proportional amount from the normal formula; the other containing contrast developer, in which the metol has been decreased by one-half, and the hydrochinon and carbonate increased in the same proportion over the normal developer. (If the second developer tends to cause fog, decrease the carbonate.). (a) Make one print in each developer, exposing so that the proper depth .is reached by the time development seems to pause. Preserve prints. Describe results. (b) Make prints from the Test Screen Negative, developing one in each developer. Compare number of distinguishable gradations.

LABORATORY MANUAL EXPERIMENT

288

No. 12.

Effect of Potassium Iodide in the Developer. (Chapters XI and XVIII.) 1. Prepare three trays of normal developer. To one, add ! grain of potassium iodide per ounce (about .03 g. per 100 c.c.), and to another, 2 grains per ounce (about .45 g. per 100 c.c.). If possible, use glossy commercial paper containing abrasion mark:i. (a) Develop one print in each tray. Examine by daylight ! minute after placing in the fixing bath. Describe color. (b) Fix prints thoroly and preserve. Compare prints lLS to abrasion marks and contrast. State conclusions. EXPERIMENT

No. 13.

Effect of Omission of Certain Chemicals from Developer. (Chapter XI.) 1. Mix four portions of normal paper developer, omitting in turn: (a) metol, (b) hydrochinon, (c) sulphite, (d) carbonate. Make five prints from one negative, using the same paper and exposure. Develop one in normal developer and one in each portion where some chemical has been omitted. Describe results as to time of development, color, and contrast. Preserve prints. 2. Increase exposures where necessary and see if good prints are possible. State results. FIXATION EXPERIMENT

No. 14.

Exhaustion of Fixing Bath. (Chapter XII.) 1. (a) Place a strip of unexposed bromide paper in a sodium sulphide bath such as is used for redeveloping. Note discoloration. (b) Place another piece of similar paper in a fresh fixing bath for 10 minutes, without exposing or developing. Rinse and remove to a sodium

284

APPlTINDIX

sulphide bath. Compare results. (e) Find shortest time of immersion in a fresh fixing bath that will prevent discoloration in the sulphide bath. How might this discoloration be used to indicate when a fixing bath is nearing exhaustion? 2. Fix a print for 10 minutes in a worn-out fixing bath, preferably one tha:t is somewhat sulphurized. If a worn-out bath is not available, fix in a good bath for only ! minute. Place print in sunlight for a day or two. Describe effect. What is the result of using a sulphurized bath? Explain the necessity of thoro fixing. TONING EXPERIMENT No. 15.

Variation in Sepia Tone thru Exposure and Development. (Chapters VIII a:nd XIV.) 1. Make three prints, giving exposures as follows: (a) Underexposure, making it necessary to force in development, taking 3 minutes or longer. (b) Correct exposure, taking about 1! minutes to develop. (c) Overexposure, so the print will be dark enough in ! minute. Prints should be made on the same kind of paper a:nd be developed to the same depth. Tone all the prints at one time. Preserve prints. Compare results. 2. (Optional). Repeat, using another brand of paper giving either warmer or colder tones. EXPERIMENT No. 16. Comparison of Toning Methods. (Chapter XIV.) 1. Make four identical prints on a paper giving normally warm tones, using a normal developer. Tone one print each (a) in regular hypo alum sepia bath, (b) inhypoalumgoldsepiabath, (c) inliverofsulphur oath, (d) by redevelopment method. Preserve prints and label carefully. State general conclusions. 2. Repeat, using a cold-toned paper.

LABORATORY MANUAL

285

WASHING No. 17. Tests for Hypo. (Chapter XIII.) 1. Permanganate Test: Make up solution as follows-Water 4 oz. (120 c.c.), potassium pennanganate and sodium hydroxide, each 4 grains (.25 g.). (a) Add three or four drops of this solution to a test tube half full of water. Note color. (b) Add a crystal of hypo or a few drops of hypo solution. Describe change in color. 2. Silver Nitrate Test: Take two test tubes about one-quarter full of water. To one add a drop or two of hypo solution. Heat both almost to boiling and add a drop of silver nitrate solution to each. Compare results. 3. Iodine Test: Boil a lump of starch the size of a pea in! oz. (15 c. c.) of water until the solution is clear. To this add a few drops of tincture of iodine solution. (a) Add a few drops of this to a test tube half full of water. Describe color. (b) Add a small crystal of hypo. What change is noted? How might these tests be applied to determine if prints are sufficiently washed? EXPERIMENT

EXPERIMENT No. 18. Comparison of Washing Methods. (Chapter XIII.) 1. Wash as follows three batches of prints, each of a dozen or more, starting at the same time: (a) Using a mechanical washer and running water. (b) Using tray method, changing prints by hand, one at a time, to fresh water and repeating until thoroly washed. (c) Leaving prints undisturbed in a tray of running water. 2. At intervals of 5 minutes, make tests for the presence of hypo in prints washed by methods (a) and (b). Pick up several prints and after the water has mostly drained away, allow the last few drops to drip into a test tube and make tests for hypo by one of the methods given in Experiment 17. As soon as (a) and

....

'286

A!»PENT)IX

(b) are found to be free from hypo, pick up sever:u prints from the bottom of tray (e) and test for the presence of hypo. Tabulate results. How many changes of water are necessary to eliminate hypo? Discuss results, as to length of time prints should be washed, giving a comparison ·of the value of the WQ,!Jhing methods under consideration. If possible, get results from others of the class or · from separate trials and list average results. ENLARGING EXPERIMENT No. 19. Relation of Expo£ure to Size. (Chapter XVII.) 1. For this experiment all prints are to be exposed so as to develop to the same depth· in the same length of time. Use the same developer and the same kind of paper in each ease. (a) Make a small projection print, perhaps 4x5. (b) Make another exactly twice the length of the first, as 8x10. (e) If paper is available, make one three times the length of the first, 12x15.

Tabulate results. Formulate rule in regard to variation of exposure with change in size of image. EXPERIMENT No. 20. Diffusion Methods. (Chapter VIII, XVII.) 1. Using one negative, make small prints of similar size by projection: (a) With anastigmatic lens, giving a sharp print. (b) With the same lens, but with a screen of two or th1·ee thicknesses of black chiffon placed over the lens during one-half of the exposure. (c) With the same lens, but with a white silk-bolting -screen placed in contact with the paper. (d) With soft focus lens wide open. (e) With soft focus lens with diffusion stop, or with sharp focus lens with diffusion disc. 2. For comparison, make a contact print by printing for one-half of the exposure with the paper in

LABORATORY MANUAL

287

contact with the negative, and the remainder of the time with a piece of glass interposed between the negative and paper. Compare as to sharpness, effect on 路retouching marks, and desirability of results. EXPERIMENT

No. 21..

Variation of Exposure and Development on Bromide Papera. (Chapter XVII.) 1. Using bromide enlarging paper, make three prints as follows: (a) One that has normal exposure so that the print will develop to correct depth in 1i minutes. (b) One that is overexposed so that the print will reach the same depth in about half that time. (c) One that is underexposed so the print will reach the same depth in about twice the time required in (a). Compare results as to tone and contrast. (d) Tone the prints under similar conditions. Compare results as to color and contrast. MISCELLANEOUS No. 22. Effect of Hypo in Developer. (Chapter XI.) 1. Make four prints from the same negative, using the same paper and giving the same exposure. Develop (a) one in normal developer;(b) one in developer to which i grain of hypo per ounce (.1 gram per 100 c.c.) has been added; (c) one in developer to which 5 or more grains of hypo per ounce (1 gram per 100 c.c.) have been added : (d) one in developer to which a little acid fixing bath has been added. Note effect in each case as regards color, time of development, contrast, stains, etc. Preserve prints. EXPERIMENT

No. 23. Effect of Dampness on Paper. (Ch.apter XI.) 1. Expose three sheets of paper on the same EXPERIMENT

288

APPENDIX

negative for an equal length of time, so that the correct development time is 1! minutes. (a) Develop one immediately in fresh developer for 1! minutes. (b) Preserve second print from light in a damp place for several hours. Develop under similar conditions to (a) for 1! minutes. (c) Preserve third print from light in a damp place for several days. Develop as in (a) for 1! minutes. Preserve prints. State conclusions. EXPERIMENT No. 24.

Effect of Sulphide Fumes on Paper. (Chapter XV.) 1. Expose two similar sheets of paper to sulphide ' fumes, when redeveloping, being careful that no white light reaches the paper. (a) Without exposure to iight, develop one of these sheets and also a fresh sheet. (b) Make a print on the other sheet and also on a fresh one. Develop. Compare results in each case. 路EXPERIMENT No. 25.

Preparation of Blue-Print Paper. (Chapter XVIII.) 1. Prepare sensitizing solution, according to formula. Filter before using. Keep in the dark. 2. Select a piece of paper with a hard white coating, and another with a rough porous surface. Apply solution with a soft sponge or camel's hair brush. Dry as rapidly as possible. Coa:ting and drying must be carried on in a darkened room. 3. Make prints on each kind of paper from a negative and also from a tracing, printing by daylight until the image is visible and the print is of a blue-brown color. Develop by washing in running water until the water remains clear. Hang up to dry. If lines are not pure white and the rest of the print a deep blue, make other trials. Compare results on different surfaces.

APPENDIX

289

B- INTERNATIONAL ATOMIC WEIGHTS (From the Smith•onian PhvaW,al Table• 1922.) .;

..Q

en Aluminum Antimony Argon Arsenic Barium Bismuth Boron Bromine Cadium Caesium

~i'i c: .. ~.22

-a... en

;as~

Sb A As Ba

120.2 39.9 n.96 137.87

Bi B Br

209.0 10.9 711.92 llUO 182.81

g =

~ ..Q

.s ..

ceo - - -2'7.0 - 3. -Al

Cd Ce

f'alcium Carbon Cerium Chlorine Chromium

Cobalt Columbium Copper Dysftroeium Erbum ·

Co Cb

Ce Cl Cr Cu

Dy Er

'D.07 12.006 140.26 36.411 62.0

8, 6.

8, 5. 2.

a. 6.

3. 1. 2.

a.'· 1.

2, a. 8.

58.117 113.1 68.67 11ll!.Jj 167.7

2,8. 6. 1. 2.

162.0 19.0 167.3 70.1 72.6

3. 1. 3. 3.

a. 3

Glucinum Gold Helium Holmium Hydrogen

Gl Au He Ho H

9.1 197.2 4.00 188.5

2. 1. 3.

Indium Iodine Iridium Iron Krypton

In I Ir Fe Kr

IU.8 126.92 1113.1 65.84 811.92

3. 1.

Lanthanum Lead Lithium Lutecinm Magnesium Manganese

139.0 207.20 8.114 173.0

Ga Ge

Pb Li Lu Mg Mn

1.001!

24.32

bUB

Phosphorus Platinum Potassium Pr8!'4!0d7mium Radium

2. 4.

Europium Fluorine Gadolinium Gallium German inn

En F

en Mercury Molybdenum Neodymium Neon Nickel [ation) Niton(Ra eman· Nitrogen Osmium O:figen P idium

Rhodium Rubidium Ruthenium Samarium Scandium

S.,leniam Silicon 'Silver Sodium Strontium

'· o.

'·

2, 3. 0.

Sulphur Tantalum Tellurium Terbium Thallium Thorium Thulium Tin Titanium Tungsten Uranium

3. , Vanadium 2. 1. '· 1 XPnon Ytterbium 8. Yttrium 2. 1 2, 7. Zinc

Zirconium

..Q

,:.

e ct

..!!"-f. ~a..,

Mo Nd Ne Ni

96.0 1U11 211.2 58.68

Nt.

222.(

.s ..

~ ---Hg 1, 2. 2110.6

N Oe 0

Pd p

• pt

lUllS 190.9 16.00 106.7 31.~

K Pr

196.2 39.10 l'D.II 2116.0

Rh Rb Ru

102.9 86.45 101.7

8a So Se

tou

'6.1

a.'· 8.

0. 2,3.

3, 6. 8,8. 2. 2, '· ll. II. 2, 1. '·

a. 1.

fl, 8.

B. 3.

711.2 28.1 107.81! 23.011 87.118

2. '· 6 1.

82.118 181.6 127.5 169.2 204.0 8.16

2, 4, 6. 6. 2. '· 8. H. 1, 3.

Tm Sn Ti

1811.9 118.7 48.1 184.0 238.2

B. 2, t. '·

Si Ag Na Sr Ta Te Tb Tl Th

u v

Xe Yb Yt Zn Zr

6\.0 130.2 173.6 89.8a 611.37 90.6

'· ].

'·

ft.

'· 8. 3,6. 0. 3. a. 2.

'·

APPENnlX

C-TABLE OF SOLUBILITIES.

This list includes the more important chemicals ~ jn photclgraphic printing, ~ with their apprQxitnate soll;lbilities .at the t~rn:peratures i~tdica~. dec.=deoomposed; insol.:::;:insoluble; sol.=solu~le; s.s.=sfightly soluble; v. s.=very soluble. SDltdlility in 100 parts •I Cold water. Boilil).g' wa~. 59oF. (15oC.) 212oF. (100oC.) Acid, citt1c ........................................ 140 200 Acid, exa1ic ...................................... 10 v.s. Alu:ni, cl).rome .................................. 10 50 Aluni, ,pOtash .................................... 12 358 Amjdlill .............................................. 25 v.s. Ammonium bichromate ................ 9 v.s. Ammoliuuln eitrate .......................... 200 400 Ammonium nitrate -------------------------200 v.s. Borax ................................................ 6 200 Ferric ammonium citrate .............. 25 sol. Ferric chloride .................................. 160 sol. WO 133 Gold chlorid~ ....... ............................ Hydl'Ek!hinon .................................... 6 sol. Iodine1 ............. ................................... s.s. s.s. Mercuric chloride ............................ 7 9 4 sol. Metol .................................................. Potasslum bichromate .................... 12 94 Pohss;um bromide .......................... 50 100 Po~$ium C!lrbGnate ...................... 150 305 Potassium ehloroplatinite .............. 17 v.s. Potassium cyanide .......................... v.s. dec. Potassium :terricya.n~de .................. 40 80 Potasilium hydroxide ...................... 200 v.s. Potassium iodide ............................ 120 200 Pohssium metabisulphite .............. 35 v.s. Potas11ium oxalate .......................... 33 50 Potassium pel1Danganate .............. 6 10 PotllSsium sulphQcyanate .............. v.s. v.s. Silver bromide ................................. insol. insol. Silver chloride ····························---~ insol. insol. 1

v.s. in alcohol or solution of potassium iodide.

:] .I

j j

~----~-

--~-,-.--

----...--..-.....

Silver nitrate ............................•....... Sodium carbonate ............................ Sodium chloride .................................. Sodium citrate ................................ Sodium hydroxide ............................ Sodium phospllate .............................. .Sodium sulphide .............................. Sodium sulphite .................................. Sodium thiosuipbate (hypo) ........

100

200

445

204

v.s. 15 v.s. 25 100

v.s. v.s• v.s. 108 v.s.

With but few and unimportant exceptions the· following generalizations can be made in regard to the solubilities of certain compounds: (a) All ammBnium, potassium, and sodi:um oom;pollftds are solulile in water. (b) All ettrbontttes are imotuble, except thGse of ammonium, :potassium, and sodium. (c) An ohloriies are soluble, exeept those of lead (sligh.tlysoluble), mercury (mercurous) and silver. (d) All nitrates, chlorates, and acetatea, are soluble in water. (e) AU oxides and hydroxides are imoluble, except those cYf amm6nium, barium, potassium, and sodium; calerum hydroxide is slightly soluble. (f) All sulphates are soluble, except those of barium, calci'llm (slightly soluble), and lead. Mercurous and silver .sulphates are but slightly soluble.

292

APPENDIX

D-TABLE FOR REDUCING AND ENLARGING All fi gores in table are in inches Focus of LensUaed

3 3~

4 4~'

5 5~

7 8

10 11

Same Rize

Size

REDUCTIONS t ' 1 !

Size

stze

Size

ENLARGEMENTS

Size

7 8 Times - 9 - 12""---w 1 8 21 -2.-- 2'1 3i 3J 6 4 4i 3! 31 .Bt 2 1 ~ -~ 3ii 7 liij 1 4 4n 4 7 4i 41 4! au 5t 8 1 2 1 6 ""20 2 4 2 8 3 2 3 6 4i 6 5 4f 8 4l 5! 4! - 9 - 13I- ----ys 2'1 ----ail ---s6 401 221 5t 6 9 5l 5n 6t 5I 5i 10 ~ 20 25"" 3 i l ----as 4 i t ~ 6 5J 10 51 71 6i 51 6l 11 l6f" ~ 27f 3 3 3"8i 44 49l 11 8t 71 61 ~ 6-ft 6J 6& 12 1 8 2 4 3il 36 4 2 ~ ~ 9 8 7 12 6J 71 7! 6! ---~,- 2 1 ~ ----as- ~ 4 9 5 6 6 3 8 14 101 91 8! 71 8l 8i 16 2 4 -32- ----.o- ~ -56- -64- 7 2 16 12 9 91 10i 10 9t 91 18 2'1 3 6 45- -54- 6 3 7 2 8 1 18 . 131 12 llt 10! 10i lOJ 101 20 -00 4 0 5 0 -----oo -70 so 9020 15 _1!l__ ~ 12 ___!!l_ _J._!L __l!t__ 33 55 22 44 66 77 88 99 22 161 14i 13! 131 121 12f 121 6o24 3 6 ~ 7 2 -----sr 96 108 18 15 24 16 14! 14 13J t3L Sam.. Size

-,-

3 1

Times Times Times Times

Times Times

----m-

KnOWing the degree of (linear) enlargement or reduction and the focal length of the lens, look up thel figures for enlargement or reduction in the horizontal row near the top. Follow down the vertical column until opposite the focal length of the lens in the left hand column. When enlarging, illhe heavy figures wlhere the two lines join give the distance from the nodal point CYf the lens to the sensitive paper, the light ones showing the distance from the lens to the negative, or picture /being enlarged direct in the camera. When reducing, the distances are viceversa. The cap end of the lens should face paper in enlarging, and in reducing should f81Ce object being copied.

APPENl>lX

298

E-BIBLIOGRAPHY. The following list of books includes not only those to which reference is made in the text, but also a number of others which bear more or less directly on printing and finishing, or which serve as a background for an adequate understanding of the photographic processes involved. These may be obtained in most cases from regular photographic publishing houses. Air Brush. Air Brush and the Photographer, The. (PhotoMiniature No. 181.) 40 cents. Air Brush in Photography, The, by G. F. Stine. 144 pages. $3.50. Treatise on the Air Brush, by F. W. Frazer. 68 pages. $1.50. Art and Composition. Essays on Art, by John Burnet. 100 pages. $2.00. Exhibition Print, The. (Photo-Miniature No. 188.) 40 cents. Pictorial Composition and the Critical Judgment of Pictures, by H. R. Poore. $4.00. Pictorial Landscape Photography, by the Pietorialists of Buffalo. 236 pages. $3.50. Pictorial Photography, by Paul L. Anderson. 301 pages. $3.00. Backgrounds. Putting Backgrounds into Portrait N egativea. (Photo-Miniature No. 126.) 4J> cents. Color Photography. By-Paths of Color Photography, by 0. Reg. $1.50. Color Photography, by C. E. K. Mees. (Photo-Miniature No. 183.) 40 cents. How to Make Prints in Colors, edited by F. R. Fraprie. 62 pages. Cloth $1.00; paper 50 cents.

394

APPENDIX

Color Photography (continued). Photography in Colors, by G. L. Johnson. $4.00. Practical Color Photography, by E. J. Wall. 248 pages. $3.00. Enlargiag. How to Make Enlargements, edited by F. R. Fraprie. 67 pages. Cloth, $1.00; paper, 50 cents. Photographic Enlarging, by R. C. Bayley. $1.75.

Finishing. Practical Frame Making, W. L. Noverre. 90 cents. Sketch Portraiture, by J. S. Adamson. 26 pages. 50 cents. General. Chemistry for Photographers, by W. R. Flint. 205 pages. $2.50. Chemistry for Photogra;phers, by C. F. Townsend. 129 pages. 75 cents. Elementary Photographic Chemistry. (Eastman Kodak Co.) 78 pages. Free. Fu.ndamentals of Photogra;phy, by C. E. K. Mees. $1.00. Modern Phtltographic Developers. (Photo-Miniature No. 167.) 40 cents. Optics for Photographers, by Hans Harting. 224 pages. $2.50. Photographic Chemistry, by P. N. Hasluck. 160 pages. 75 cents. Photographic Emulsions. (Photo-Miniature No. 179.) 40 cents. Photography for Students of Physics and Chemistry, by Louis Den-. $2.25. Photography: Its Principles and Applications, by Alfred Watkins. 349 pages. $4.00. Science and Practice of Photography, The, by J. R. Roebuck. 298 pages. $2.50.

APPENDIX

285

Lantern Slides.. How to Make Lantern Slides, edited by F. R. Fraprie. 74 pages. Cloth, $1.00; paper, 50 cents. How to Make Lantern Slides. (Photo-Miniature No. 130.) 40 cents. Lantern Slides, by F. A. Hoschke. $1.00. Lantern Slides-How to Make and Color Them. (Eastman Kodak Co.) 32 pages. Free. Practical Slide Making, by G. T. Harris. 90 cents. Miscellaneous.

American Annual of Photogratphy, The. $1.50 (Published annually.) Chemistry of Development, by J. W. Wishka. 99 pages. $1.25. Commercial Photographer, by L. G. Rose. 147 pages. $4.00. Photo-Engravers' Hand Book on Etching and Finishing,' by P. C. Raymer. 101 pages. $1.50. Photographic Researches of Hurter and Driffield, The, edited by W. B. Ferguson. 374 pages. $9.00. Silver Bromide Grain of Photographic Emulsions, The, by A. P. H. Trivelli and S. F. Sheppard. 143 pages. $2.50. Papers and Processes. Blue Printing and Modern Plan Copying, by B. J. Hall. 130 pages. $2.00. Bromide Printing, by F. C. Lambert. 90 cents. Bromoil and Oil Prints, by J. A. Sinclair. $1.00. Bromoil Prints and Bromoil Transfers. (PhotoMiniature No. 186.) 40 cents. Carbon Printing, A. B. C. Guide to. (Autotype Co.) 75 cents. Carbon Printing, A New Treatise on the Modern Methods of, by A. M. Martin. 260 pages. $2.50,

Papers and Processes (continued). Carbon Printng. (Photo-Miniature No. 86.) 40 cents. Carbon Printing. by E. J. Wall. 104 pages. 90 cents. Kallitype and Allied Processes. (Photo-Miniature No. 185.) 40 cents. Platinum Printing. (Photo-Miniature No. 115.) 40 cents. P. 0. P., by A. H. Hinton. 134 pages. 90 cents. Practical Printing Process, edited by F. R. Fraprie. Cloth, $1.00; paper, 50 cents. Printing Papers. (Photo-Miniature No. 78.) 40 cents. 路 Toning Bromide and Gaslight Papers. (PhotoMinia:ture No. 103.) 40 cents.

Reference. British Journal Photographic Almanac, The. (Published annually.) Dictionary of Photography, by E. J. Wall. 700 pages. $5.00. Figures, Facts and Formulae of Photography. (Photo-Miniature No. 173.) 40 cents.

iNDEX A Abrasion marks, 172, 231 Accelerators, 112 Acetic acid, 133 Acids, 47 acetic, 133 caution, 59 dilution of, 59 used in photography, 46 Air brush, Easter egg design, 196 finishing, 195 improving negatives, 80 outfit, 37 YJgnetting, 94, 101 Albcrt'ne stone, 27 Albumen papers, 65 Alkalis, effect on developers, 112 i,ypes of, 117 ~·"e in photography, 46 Alum, 133 Amidol, 115 developer. 131 A.pprenticeShip, 18 Atomic weight, 42 table, 289 Atoms, 41 Avoirdupois weights, 51 Autoehromes, 267 B Backgrounds, 81 Backing, commercial prints, 235 doretypes, 250 Baryta coating, 63 Bases, 47 Blisters, 172-175 Blocking, 224 Blotters for drying, 147 Blue prints, 241, 288 Blue· tones, 167 Bolting eloth, 216

Bottles, 30, 31 Bromide papers, compared with chloride, 64, 220 composition, 65 exposure and development 287 Bromoil prints, 263

Carbon printing, 257-260 three-color, 271 Carbro process, 260 Cheese cloth racks, 147 Chemical changes, 41 (;hemieals, developer, 114-117 fixing bath, 132-134 impurities, 53 preservation of, 36 solution of, 55 Chemistry, 40-50 of 'blue printing, 242 of development, 111 of fixation, 135 of hypo alum toning, 1:i5 of light action, 90 of platinum printing, 25~ of short stop, 135 Chloride papers, manufacture 62 Cleaning, prints, 193, 199 solution, 117 Collodi~chloride ,papers, 65 Color, 266 choice of, 151 complementary, 269 photography, 26& printing, 269 suitability, 68 unsatisfactory, 175 Coloring, commercial prints, 239 after treatment of, 241 lantern slides, 24 7 oil, 197 •

298

INDEX

Coloring-Continued pastel, 198 water, 198, 247 Color-printing, 265-274 additiv~ methods, 269 autochromes, 267 negatives for, 268 Paget plates, 268 selective a:bsorption, 269 subtractive methods, 270-274 theory CJI!, 270 Combination printing, copying method, 105 masking method, 106-110 Commercial prints, 223-242 backing, 235 coloring, 239 development, 230-232 dye--proofing, 240 exposure, 229 ferrotyping, 233 hinges, 235 mounting, 236 papers, 228 preparation, 224 standards, 228 Compounds, 41 Contrast, choice of, 73-78 excessive, 175 lack of, 177 scale in lighting, 69 scale in negative, 70 scale in paper, 71 Conversion table, 52 Copying, 105, 177, 181 Crayon sauce, for finishing, 202 for improving negatives, 80 for vignetting, 95 Cyanide-iodide reducer, for abrasion marks, 23~ for commercial work, 237 for vignetting, 102, 23a Cyanotype process, 241

D Dampness, effect on health, 24 effect on papers, 124, 288 Defects in prints, 170-183 Deliquescence, 46 Deposits, 176 Desensitizer, 268 Developing papers, 62-65 Development, affecting sepia tones, 284 chemistry of, 111 commercial prints, 232 correct, 126 defects, 129 enlargements, 219, 287 lack of, 130, 283 lantern slides, 245 local, 127 preparation, 123 process, 125 to secure soitness, 129

uneven,188 Developers, amidol, 131 commercial, 230 exhaustion of, 131 function, 111 impurities, 130, 287 lantern slides, 245 metol-hydrochinon, 118-131 potassium iodide in, 283 temperature, 124, 282 variations, 127, 281, 282, 283 weak and strong, 220 Diffusion methods, contact, 87 enlarging, 215, 286 Distillation of watct路, :i4, '.:78 Dodging, commercial printing, 229 contact printing, 86 enlarging, 218 Doretypes, 250 Drawings, 2lf6, 238

INDEX Drying, 146-148 machines, 147 methods, 147, 233 ra'Pid, 146 rate of, 146 Dry mounting tissue, 236 Dye-proofing, 240 E Efforescence, 46 Elements, 41 Embossing, 191 Emulsions, 63 Enlarging, (see Projection printing) Equations, 44, 45 Equipment, commercial, 224, 229, 23:3 enlarging, 205-212 finishing, 37-38, 189 printing, 30-35, 81 Experimentation, 19, 276 Experiments, 276 Exposure, bromide and chloride papers 84 commercial prints, 229 correct, 82, 83 enlargements, 216, 286, 287 factors affecting, 86 lantern slides, 245 length of, 84-86 test rack, 84 test strips, 85 F Fading of prints, 177 F'errotyping, 233 Finishing, 184-203 air brush, 195 commercial prints, 233 enlargements, 221 steps in, 184 Finishing room, 27-29 Fixation, 132-141 chemistry of, 135

299

Fixing bath, 135-141 capacity, 140 defective, 172 exhaustion, 141, 283 formula, 137, 240 hardener, 137 action of, 139 lantern slides, 246 milky, 138, 139 preparation, 137, 279 use of, 140, 232 Flattening, 149 Floors, 26 Fluid measure, 51 Fog, cause of, 130 chemical, 178 developer, 178 light, 178 prevention of, 179 Folders, classification of, 38 types of, 187 Formulae, amidol developer, 131 blue print, 242 blue toning, 168 chemical, defined, 43 cleaning solution, 117 commercial developer, 231 cyanide-iodide reducer, 237 desensitizer, 269 fixing bath, 137, 240 flattening solution, 1 H green toning, 169 hardener for fixing bath, lS7 hardener for sepia baih, 157 hypo alum bath, 15!, 1;)'3 hypo tests, 145 lantern slide, 245, 246 liver of sulphur, 165 metol-hydrochinon developer, 119 non-abrasion developer, 231 platinum developer, 256

soo Formula~ontinued

P. 0. P., 253 re-bleaching sepias, 165 redevelopment, 161 red toning, 167 short stop, 134 soft-contrast developer, 121 stain removal, 182 stripping solution, 227 three-solution developer, 123 waxing solution, 234 Framing, equipment, 37, 201 mats, 199 moulding, 200 G Gelatino-chloride papers, 65 Glass, cleaning, 94 Gradation in sepias, 152, 153 Graduates, 31 Green tones, 168 Gum printing, 261, 262 three-color, 272 H

Hardener, for carbon prints, 260 for fixing bath, 137 for sepia bath, 157 Hinges, 235 Humidity, 124 Hydroehinon, 114 Hydrometer test, 57 Hypo, 132 eliminators, 146 in developer, 287 non-removal of, 146 tests for, 144, 285 use of, 133 Hypo alum sepia bath, 153-160 chemistry of, 155 exhaustion, 157 formula, 154, 158 gold batli, 158 method of use, 156

modifications, 158-160 preparation, 154, 279 temperature, 156, 279 I Intensification, of negatives, 79 of prints, 163 Iodine test for hypo, 145, 285 Ion, 47, 48 Ionization hypothesis, 42, 92 K Knowledge, scientific:, 17, 18 L Lantern slides, 243, 249 coloring, 24 7 development, 245 exposure, 245 fixation, 246 mounting, 248 size, 243 titles, 248 use, 243 Latent image theories, 91, 92 Law of Conversation of Energy, 43 Lenses, enlarging, 211 Light action, chemistry of, 9092 Lighting, scale of contrast, 69 Lights, are, 210 enlarging, 210 for commercial printing, 228 for printing, 32, 82 mereury vapor, 210 Liver of sulphur bath, 164 M

Masks, combination printing, 106 lantern slide, 248 Mats, far framing, 199 Matter, properties of, 43 Mercuric chloride, 36, 163 Metol, 114 oxidation of, 278

INDEX Metol-hydroehinon developer, mixing, 119, 278 modification, 120 normal, 119 soft-eontrast, 121 three-solution, 123 Metric system, 52 Molecular strain hypothesis, 91 Molecular weight, 42 Molecule, 40 Mordanting, 247, 274 Moulding, 199 Mounting, commercial, 236 dry,236 lantern slides, 248 portraits, 192 transparencies, 249 Mounts, color, 185 function, 184 kinds, 186 selection, 184 shape, 188 size, 186 N Negatives, color-separation, 268 commercial, 224, 226 etching, 226 fogged, 178 for sepias, 152 for vignetting, 94 ideal, 78 improvement of, 79-81, 224 lantern slide, 244 long scale, 73, 280 normal exposure, 70 scale of contrast, 70, 78 short scale, 76, 280 test screen, 72, 280 Neutralization, 48, 277 Non-abrasion developer, 231, 283 0 Oil printing, 262-264

301

transfers, 263 Opals, 249 Opaque, for blocking, 224 for improving negatives, 80 for vignetting negatives, 94 Overdevelopment, 130, 176 Overexposure, 83, 176 Oxgall, for cleaning, 94 Oxidation, 49 prevention of, 49, 122, 123 study of, 277 Oxidizing agents, 49 Oxy-chloride hypothesis, 92 p Paget plates, 268 Permanganate test, 145, 285 Phenosafranin, 268 Photo-engraving, 273 Physical changes, 40 Pinatype process, 273 Plastocine, 80 Plate-sinking, 189 . Platinum printing, 255-257 Poisoning, metol, 21, 131 Poisons, mercuric chloride, 36, 163 potassium cyanide, 36, 237 Post-office paper, for combination printing, 107 for vignetting, 98 Potassium bromide, 117 use of, 117, 123, 281 Potassium cyanide, 36, 237 Potassium ferricyanide, 161 Potassium iodide, in non-a:brasion developer, 172, 283 to secure softness, 129 Potassium permanganate, 145, 285 Potassium sulphide, 164 Preservatives, 112 Press, flattening, 38

INDEX Printing, commercial (see) importance of, 17 in colors, 265-274 quick, 230 . Printing frame for vignetting, 96 Printing machine, amateur finishing, 229 home-made, 32 lights, 82 profes路sional, 81, 82 qualifications of, 31 timer, 82 types of, 31, 228, 229 路ventilation, 31, 32 wiring of, 32, 33 Printing-out papers, 65-66, 252264 pictorial, 254-264 self-toning, 254 silver, 252 Printing room, arrangement, 24 cleaning of, 24 combination, 20 entrance, 25 1h>ors, 26 heating, 27 location, 20 plans, 22, 23, 24 sanitation, 21 separate, 21 sinks, 27 walls and ceiling, 26 Printing papers, albumen, 65 blue print, 241, 288 !bromide, 64, 220 bromoil, 263 carbon, 257 chloride, 62 choice of, 87-78 collodio-chloride, 65, 252 commercial, 228

composition, 62 contrast, 78 developin-g, 62 effect of humidity on, 124, 288 enlarging, 212 gelatino-chloride, 65, 252 gum, 261 hard, 78 long scale, 73, 77, 280 normal, 78 plain silver, 65 platinum, 255 printing-out, 64, 252-264 range of tones in, 77 scale of contrast, 71 short scale, 76, 280 so:(t, 78 sto<;k and surface, 87 toning, 152, 154 Prints, cleaning, 193, 199 dark, 176 flat, 177 mottled, 179 muddy, 179 weak, 183 Projection printers, 205-210 Projection prints, 204-222 advantages, 204 development, 219, 287 diffusion, 215, 286 disadvantages, 205 drying, 221 equipment for making, 205212 exposure, 216, 286, 287 finishing, 221 fixing, 221 focusing, 213 life size, 222 table for enlarging, 292 toning, 221 vignetting, 219 washing, 221

INDEX Pumice powder, 202 R

Raydex thTee-eolor process, 272 Reactions, 43 Reagents, developing, 111, 113 Red tones, 167 Redevelopment, 160-164 chemistry of, 162 enlargements, 221 fonmula, 161 variations, 162 Reducing agents, 49 Reduction, 49 of negatives, 79 Relief processes, 273 Restrainers, 112

Safelights, indirect, 34 kinds of, 33 standards, 33 路testing, 280 Wratten, 33 Salts, photographic, 48, 49 ~and for vignetting, 101 Sanitation, 21, 24 Seales, kinds of, 34 Schools, photographic, 18 Sensitiveness cf paper, 64 Sepia bath, (see Hypo alum sepia bath) Se,pias, effect of bromide on, 281 factors affecting, 166, 284 gradation of, 152 hy路po alum, 153-160 liver of sulphur, 164 ,:ermaneney of, 152 purple, 156 re-bleaching, 165 redevelopment, 160-164 toning methods, 153-166, 284 Short stop bath, advantages, 134 chemical action, 135

formula, 134 Silver chloride. .63, 277 in sepia bath, 155 Silver nitrate, in sepia bath, 154 test for hypo, 145, 285 Silver pa'l'tiele .hypothesis, 92 Sinks, 24, 25, 27 Sketching, 197 Sodium carbonate, 116 Sodium chloride, 154 Sodium sulphide, 161 effects of fumes, 25, 161, 288 Sodium sulphite, 49, 115 action of, 277 use of developer, 115 use in fixing bath, 133 Sodium sulphate, 49, 116, 278 Solubilities, table of, 290 Solutions, 45 cleaning, 117 dilution of, 59 filtration of, 60 methods of mixing, 56 percentage, 57, 58 preparation of, 51-61 saturated, 45 stock, 60, 61 storage device for, 122 strippin~, 227 Solvents, 45 Spots on prints, 179 Spotting, 193 Stains, oxidation, 181 removal of, 182, 183 silver, 180 Stripping solution, 227 Sub-haloid hypothesis, 91 Sunk centers, 189, 191 Su,pplies, chemical, 36 finishing, 38 printing, 35 . Surface of printing papers, 67

304

INDEX

T Temperature, developer, 124, 282 effect af change in, 174 for waS'hing prints, 142 路 regulating, 125 sepia bath, 156, 279 Test seTeen negative, 72, 280 Test strips, 85 Timer, 82 Tinted borders, 88 how to print, 90 Tinting, lantern slides, 247 prints, 202 Tinting masks, 89 Titles, on lantern slides, 248 on prints, 227 Tonal values, 69-78 range of, 83, 152 Toning, 151-169 -blue, 167 chalk red, 167 combination, 169 defined, 153 enlargements, 221 green, 168 lantern slides, 24 7 P. 0. P., 253 sepia, 153-166, 284 Transparencies, 249 Trays, developing, 123 for sepia bath, 156 kinds, 34 sizes, 34 Trimming, 188 Trimming boards, 37

Underdevelopment, 129

Underexposur~

Valence, 43 Ventilation, 21, 26 Vigne'ttes, 93 combination, 102 negatives for, 94 suitability of, 93 tone of, 151 Vignetting, commercial prints, 230 enlargements, 219 mechanical devices for, 95 methods, air brush, 101 cyanide-iodide, 102 post-office paper, 98 路 printing frame, 96 sand, 100

Walls of printing room, 26 Washing prints, 142-146, 232 methods, 143, 285 necessity for, 142 temperature of water, 142 time of, 144, 285 Water, 53 impurities, 53, 54 purification, 54, 278 tests for purity, 54 Water of crystallization, 45 Waxing solution, for 路brilliancy, 202 for ferrotype plates, 234 Weights and measures, conversion table, 52 metric, 52 U. S. standard, 51 Windows, 26 Workroom plans, 20-29