Contents Preface
1
Introduction
2
The History of Molding and Casting The History of Ceramics The History of Gypsum The History of Copper The History of Synthetic Resins
The Mold or Cast Object and Molding Materials The Prototype or Model as an Object of Molding Reference Points Transfer of the Points to the Clay Model From the Clay Model to the Plaster Model From the Live Model Directly to the Plaster Model
Mold or Matrix or Form or Negative
3 4 4 5 9
11 11 13 14 15 17 17
18
Pre-treatments for Molding
18
Mold-Releasing Agents Soapy Water Paraffin Oil and Petroleum Jelly (Vaseline) Polyvinyl alcohol (PVA) Releasing Waxes Wet Paper Tin-Foil Talc Shellac
19 20 22 23 23 24 25 26 26
Partition of the Model
27
Partition Materials - Shims or Fences Sprues and Vents Keys Clamps and the eye hooks
28 33 35 39
Armature and the Reinforcement of Casting Materials
43
Reinforcement of Gypsum with Sisal Fiber Mesh Reinforcement Reinforcement with Fiberglass Fabrics Polypropylene (PP) and Polyethylene (PE) Staple Fibers Reinforcement with Metal Bars Vacuum Pump and Pressure Chamber for Casting Materials
43 44 45 46 47 48
Plaster, Origin - Properties Processing of Plaster Plaster Preparations Plaster Application
Plaster Molds Waste Mold Plaster Waste Mold Making Multiple-Piece Mold Molding Processes with Multiple-Piece Molds Steps of Multiple-Piece Mold Making
Rubbers - Elastomeric Natural and Synthetic Resins Advantages and Disadvantages of Synthetic Elastomers (RTV) Polysulfide Rubber - Thiokol® (Polymer)
49 50 51 52
54 54 55 60 61 62
68 69 70
III
Molding with Rubber Latex
Application of Latex by Immersion Laminated Casting with Latex Thickening Latex for Lamination Casting
71
72 74 76
Molding with Thermoforming Synthetic Rubber
77
Preparation of Thermoforming Vinyl Rubber
78
Laminated Casting of Thermoforming Vinyl Rubber
79
Applying Thermoforming Rubber by Casting
82
Silicone Elastomers or Silicone Rubbers Poly-Addition and Poly-Condensation Silicones Compared
Molding with Silicone Rubbers
84
85
Silicone Rubber Mold with Laminated Casting
85
Shim or Fence for Silicon Rubbers Mold Releasing Agents for Silicone Molds Silicon Laminated Casting Using Thixotropic Agents
86 86 87
Detailed Molding Processes with Laminated Casting
88
Molding by Lamination Casting of Delicate Objects
91
Molding Using Tin-foil
92
Molding with Silicone Rubber Putty
94
Putty Silicone Application on a Full-Body Sculpture
94
Putty Silicone Relief in Application
96
Molding With Silicone Rubber Molding
97
Making the Gap Between the Model and Mother Mold
97
Calculating the Silicone - Catalyst Ratio
98
Extra Steps- Ducts in the Rubber Mold for Inlet of the Casting Material
100
Casting Failures in Silicone Rubber Molds
101
Casting With Silicone Rubber
102
The Simplest Molding Technique With Silicone Rubber
102
Cutting the Rubber Mold
103
Molding Small Full-Face Sculptures With Shims and Fences
105
Silicone Casting in the Gap Between Model and Mother Mold
107
Multiple-Piece Silicone Mold
115
Double-Sided Mold Double-sided Mold of a Flexible Model
119 120
Vulcanized Silicon Molds (HTV)
125
Rubber Molds Without a Vulcanizer
126
HTV Silicone Rubber Molds With a Vulcanizer
129
Molding a Live Model
131
Molding an Arm or Leg With Plaster
132
Face Casting With Plaster Gauze
134
Body Molding With Plaster Gauze
135
Alginate Rubber Mold
IV
83
137
Molding alginate by immersion
137
Alginate Mold by Coating
139
Facial Molding With Alginates
142
Molding a Live Model With Body Silicones
144
Molding a Live Model With Body Silicone Rubber
145
From the Body Cast to the Replication Mold
148
From the simple mold to the main double-sided mold
149
Inner Mold or Core
Molding With Synthetic Resins
153
157
Casting With Elastomeric Polyurethane
157
Molds Made of Rigid Resins (Acrylic, Epoxy, Polyurethane)
159
Resin Casting Using a Vacuum Pump
164
Casting by Suction in a Vacuum Mold
Molds With 3D Printing
From Molding to Replication With Various Casting Materials Opening the Waste Mold by Chipping
172
177
181 182
Opening the Waste Mold by Chipping
186
Casting Plaster of Paris in Multiple-Piece Molds
190
Casting a Large Plaster Relief Using a Multiple-Piece Mold
193
Casting Plaster in a Rubber Mold
195
Additional Work on Plaster Castings – Support
197
Casting With Hard Plaster (Dental)
199
Hard Plaster Casting Processes
200
Mixed Process – Casting and Laminated Casting
202
Laminated Casting With Hard Plaster
203
Retouching Hard Plaster
205
Clay Origin and Properties Casting With Clay The Mold for Slip Casting Clay
207 209
210
Production of Ceramic by Slip Casting
213
Preparing the Clay for Slab Casting
215
Slab Casting
216
Retouching in Clay
220
Slab Casting Clay in a Silicone Mold
221
Summary of Clay Slab Casting Procedures
223
Casting with Cement Mortar
228
Laminated Casting With Cement Mortar
229
Casting With Full-Body Hollow Cement Mortar
231
Casting With Synthetic Resins
234
Admixtures, Fillers and Reinforcement Materials for Resins
236
Aggregates and Fillers for Resins Reinforcement of Resins With Glass Fabrics
237 241
Resin Pigments
243
Mold-Releasing Agents for Resins – Application Procedures
246
Technical Data - Chemical and Physical Properties
248
Usual Technical Processing Instructions from Manufacturers
249
Processing of Resins
252
Acrylic Resin
253
Polyester Resin
254
Crystal Clear Polyester Casting Resin
255
V
Epoxy Resin
256
Transparent Epoxy Resin – Liquid Glass Flexible Epoxy Resin
257 258
Polyurethane Resin
258
Polyurethane Types
259
Casting With Acrylic Resin
263
Mother Mold With Acrylic Resin
265
Acrylic Resin Coating
267
Acrylic Resin as Undercoat Instead of Mortar
268
Casting With Polyester
269
Polyester by Laminated Casting
270
Polyester Hollow Sculpture by Laminated Casting
271
Retouching Polyester
274
Casting With Epoxy and Polyurethane Resins
VI
261
Acrylic Resin Mixed With Metal Powders
275
Processing of Epoxy and Polyurethane Resin
278
Casting Transparent Resin or Liquid Glass
279
Coating Resins for Objects and Images
280
Transparency Recovery With Resin
281
Two-Component Water Primer and Coating Epoxy Resin
281
Model Polishing With Coating Epoxy Resin
282
Model Glossing With a Two-Component Epoxy Primer
283
Model and Mold for Producing a Transparent Object
284
Surface Coloring With Transparent Coating Resin
285
Casting in an Open Mold With Opaque Epoxy Resin
286
Transparent Epoxy Casting in an Open Mold
287
Casting in an Open Mold With Transparent Epoxy Resin
288
Liquid Glass or Crystal-Clear Epoxy Resins
289
Crystal-Clear Polyurethane Transparent Resin
290
Object Encapsulation in Liquid Glass Resins
291
Bubbles in Synthetic Resins
292
Synthetic Resin Surface Polishing
294
Retouching and Finishing Laminated Resins
296
Casting Transparent Polyurethane With Aggregates Fast-Casting Polyurethane in a Vacuum Chamber
297 299
Casting in a Pressure Chamber
301
Gradual Casting of Synthetic Resins
302
Epoxy Resin Laminated Casting
304
Expanding Polyurethane
306
Expanding Polyurethane as a Cast Filler
306
Rigid Expanding Polyurethane in Direct Casting
308
Rigid Semi-expanding Polyurethane
309
Semi-expanding Polyurethane as a Casting Filler
310
Pressure Casting of Expanding Resins
311
Expanding Epoxy Resin
312
Polyurethane Rubber for Casting Replicas
313
Flexible Polyurethane Foam
314
Epoxy Coating Resin by Vacuum Infusion
315
Molding With Body Silicone Rubber
318
Casting a Lifelike Silicone Figure
319
Detailed Silicone Rubber Casting
323
Casting Silicone in a Double-Sided Mold
325
Mask Making by Casting Latex
329
Papier Mâché With Pulped or Mashed Paper
333
Making Objects With Pulped Paper
335
Making Objects by Gluing Shredded Paper
337
Using Wax in Molding, Casting, and Replication Lifelike Wax Figure-Making
Brass and Bronze Casting
339 341
347
Sand Casting
347
Sand Casting Process
349
Sand Casting Equipment
350
Description of Sand Casting Processes
351
Lost-Wax Casting or Investment Casting
355
Wax Model
356
Wax Model by the Massive Casting Method
357
Wax in Microsculpture and Silversmithing
358
Welding and Retouching Wax
359
Working in a Metal Foundry
361
The Spruing System
361
Investment or Ceramic Shell
362
Burnout
363
Casting
364
Casting by the Lost-Wax Method
365
Steps of Metal Casting by Gravity
365
Metal Casting by Gravity in Pictures
366
Casting With the Lost Wax Method in Detail
368
Foundry Centrifuge and Vacuum Casting Equipment
376
Centrifugal Casting
378
Vacuum Casting
382
Defects and Failures in Metal Casting
384
Retouching Metal
386
VII
Lost-Wax Casting or Investment Casting
391
Patina on Plaster Casts
392
Oil Patinas on the Plaster Copy – Imitating Marble
393
Oil Patina on Other Materials
395
Patinas With Acrylic Paints – Imitating Bronze Oxidation
396
Patina on Ceramics With Acrylic Paint Glazes
399
Patinas With Wax Varnishes
405
Inner Patina for Resins
407
Coloring and Imitation With Transparent Resins – Liquid Glass
409
Exterior Transparent Resin Surface Coloring
410
Internal Transparent Resin Surface Coloring
412
Coloring a Silicone Cast
413
Surface Coloring of Resins With Acrylic Paints
415
Gilding and Plating
415
Patina With Chemical Oxidation on Acrylic Resin
416
Patina on Brass and Bronze
417
Cold-Acting Oxidation of Brass and Bronze
417
Brown Cold-Acting Oxidation Process
418
Green Cold-Acting Oxidation Process
420
Oxidation of Brass and Bronze by Heating
421
Detailed Procedures for Applying Patina by Heating the Metal
423
Varnishing Metal
426
427
Tablets
VIII
Safety
427
Temperature Comparison
430
Ounces to Grams formula and Vice Versa
430
Convert from Pounds to Kilograms and Vice Versa
431
Inches to Centimeters Formula and Vice Versa
431
Glossary of Technical Terms
432
Bibliography
437
About the author
440
Preface The process of writing this book began in 2005. At first it consisted of aggregating notes for the students of the Sculpture Studio in the School of Fine Arts at Aristotle’s University of Thessaloniki.
Second, the clients I worked with outside the university were asking me to create everything they imagined that could undergo pouring or casting, but that they could not create themselves.
But then the need for a book that would contain all the know-how I had acquired in my 40 years of involvement with what we could call the "kitchen of sculpture" became apparent.
Fortunately, the imaginations of both students and customers contributed to my acquisition of extensive knowledge of modern materials.
I consider it a necessity to preserve this knowledge by passing it on to those who need it. After all, after several years of teaching, I was left with the difficulty of passing on knowledge without barriers or trade secrets for personal use.
Moreover, I decided to create this book in order to demystify the process and counter the belief that in the era of scanning, computer processing and 3D printing, one can escape molding and casting.
It is useful to bear in mind that scanning is not as easy as we imagine. Computer processing I had to teach lessons in plasterwork when I be- demands qualifications that a sculptor doesn’t gan teaching at the laboratory of sculpture. Their have, and the faults of 3D printing cannot be corrected using a computer. purpose was for students to learn plaster casting from clay patterns and reproduction of a plaster cast which would later be the model for The greatest contribution of such a procedure imprinting either on marble (by carving) or on is its ability to scale (especially when scaling brass (by casting). down). Since that time, these lessons at the school have been based on centuries-old tradition. They offer essential knowledge about the history of casting and its practice on contemporary materials.
Further, I counter the idea that YouTube or similar videos are sufficient to learn about subjects we are searching for knowledge of, where people seeking recognition present knowledge that they may not have truly obtained at all.
Nevertheless, the evolution of molding and casting materials and techniques has eased the pro- YouTube knowledge is mostly presented by amateurs. It is fragmentary information and cedure of casting and spread knowledge of alcannot offer deep knowledge, and it depicts ternatives for reproduction of a work of art. magical results without focusing on the basics Two things contributed to the enrichment of the of casting. This book can lead the reader to distinguish quality teaching on YouTube. course with its accompanying equipment and techniques: The first was the students’ search for new materials when it was time to write their theses.
1
Introduction A mold or negative is constructed from a liquid material which, when solidified, reflects the shape of a solid body, what we call a model. From this process, what we call a matrix, formula, mold, or negative emerges. A copy can also be made by casting a fluid which solidifies in the mold. The reproduction is called a cast, copy, or positive. Thus, while the mold is the negative representation of the original, the cast is its exact copy. Over time, the term cast came to be used for the reproduction of the pattern, while the terms matrix, type or mold remained in use for the impression. The pattern or model can be, for sculptors, any object: a clay model, plaster model, artwork (marble, bronze, ceramic), living model, etc. The mold is necessary for casting and can be made of polyester, epoxy resin, liquid clay, liquid cement, wax, etc.
2
It is also necessary for "pressing" the impression, i.e., with cement or clay for ceramic applications. The cast can range from a simple plaster replica to a complex brass-bronze sculpture. Uses of the cast are wide-ranging, both in constructing molds to faithfully reproduce casts for education and the study of art history and in preserving priceless works of art from damage caused by direct exposure to the outdoors The creation and use of the matrix is inextricably linked first to metallurgy and later to ceramics. This is why this work includes particularly extensive references to the history of copper, the properties of metals, and the processes of reproduction through the casting of brass and bronze sculptures. For the same reasons, I refer to ceramics. On the contrary, I refer to modern materials (silicones, resins, cements, etc.) mainly to demonstrate the even greater necessity of knowledge of casting when using these materials.
The History of Molding and Casting The first examples of the production The motivation for the development of works of art from clay date back to of castings throughout the then the Neolithic period. known world was the cult of the dead. From the 9th millennium BC, and from the regions of Asia Minor and the Near East, with the discovery of pottery firing, the first women's idols, symbols of fertility, appeared. The first useful objects appeared much later (in the 7th millennium) in the Catal Hoyuk region (Asia Minor) and the Sahara. Many consider Catal Hoyuk, in the Anatolia region (present-day southern Turkey), the oldest and largest Neolithic settlement.
In an effort to ensure their dead further survival, they resorted to various tricks until they reached molding. Initially, they applied light coatings to the skulls of the dead and later tried to make a funerary mask. We have very few plaster funerary portraits because of the corrosiveness of plaster. No beeswax funerary portraits exist although the Romans used beeswax widely (in funerary processions or depictions in atriums).
The settlement was discovered in the Apparently, due to the organic nature 1950s and excavations were conof the wax, it was impossible to preducted by archaeologist James Mel- serve over time. laart from 1961 to 1965. The first attempts to apply coatings It is also considered the oldest city were made during the Neolithic peri(from 8000 BC) with a significant od, when the first funerary portraits number of emerging activities such appeared. as systematic agriculture, animal After the skin of the dead person had husbandry, and primitive craft production of ceramics and copper prod- decayed, the skull was coated with a red or brown earth mortar. This symucts. bolic make-up gave the impression of Jericho is considered by others to be a face. the oldest city in the world, with the corresponding activities of Catal Hoyuk.
From Susa we have an important find from the 2nd millennium BC. In a tomb under the floors of the dwellings, a head of unfired clay, painted in a realistic manner, was discovered next to the covered face of the deceased. The earliest molds were made of stone or baked clay. The use of the mold from the Bronze Age to the present day is the most important patent for the production of multiple artifacts. Archaeology, in addition to historical research, has for years made extensive use of the mold for documentation, conservation, restoration, and reproduction purposes. In practice, it does no more than reproduce a technique of the utmost antiquity, of which it is now discovering the results. In a way, it conveys to us objects and organic bodies which, without the assistance of congruence with their form, would have disappeared for good.
Catal Hoyuk
Excavation of Jericho was begun in 1911 by the German-Austrian expedition, continued by J. Garstang from 1930–1936, and completed by Kathleen Mary Kenyon in 1952– 1956. In the middle of the 7th millennium, we have the first evidence of gypsum use in the Ain Ghazal area of Jordan.
Jericho
.
Ain Ghazal
Ain Ghazal (east of the Jordan River, present-day Jordan) is estimated to have been founded around 7250 BC and abandoned around 5000 BC. In 1983, what are thought to be the oldest plaster statues were discovered. Gary O. Rollefson continued excavations in the 1990s.
The first samples of clay art production are from the Neolithic period in the areas of Catal Hoyuk, Ain Ghazal and Jericho.
3
The History of Ceramics The use of ceramic molds in pottery to produce ceramics by slab-casting clay into a ceramic mold first appeared in the Hellenistic period. The use of plaster molds in ceramics to produce ceramic objects with slab or slip clay occurred much later (for the first time in the mid-18th century in England). The mold, in addition to boosting the production process, also assisted the potter by finely incising designs transferred to the pottery and filling them with color. The first imprinting materials used by humanity were clay, plaster, and wax.
The first materials used to model and The development of ceramic technolreproduce copies were again clay, ogy goes hand in hand with the inplaster, and wax. vention of the wheel and the development of pyrotechnology. It is easy to see, therefore, that model-making and modeling are often The development of pyrotechnology, combined or confused without distin- in both ceramics and metallurgy, guishing which came first. helped to control the temperature of the kilns and to achieve reducing or Thus, for example, the relief decora- oxidizing conditions according to the tion of an article of pottery requires a needs of the ancient craftsperson. mold, whereas the incised decoration of a mortar requires a model. In Mesopotamia initially and in Egypt afterward, we see the transition from The art of working clay, from molding open fires to kilns. to firing, is called ceramics. Ceramic products can range from simple utiliBy firing the ceramics, these civilizatarian objects to highly aesthetic tions were able to raise temperatures works of art. to reduce porosity and to color and glaze the ceramic.
The History of Gypsum At the same time as the discovery of fired pottery and in the same region (Asia Minor and the Near East), the first evidence of the use of plaster appears. The use of gypsum, with the maturation of societies and technology, passed from the Eastern Mediterranean to areas with fewer gypsum deposits. In Gaul, despite the abundance of deposits, knowledge of its use arrived with Roman occupation. To discover the properties of fired (baked) gypsum, all that was needed was a hearth that maintained a steady fire in a soil containing mineral gypsum.
Evidence of this use appears on the plastered walls and raised reliefs in the sanctuary of the temple of Catal Hoyuk.
It gave a more realistic rendering of The region of Jericho was called, in the funerary portraits, differentiating the 7th millennium BC, "the people in them from the usual funerary masks. the plaster ground." At Jericho, during an excavation in 1953 by Kathleen Kenyon, a piece of a human skull appeared in the walls of a trench. The face was coated in plaster, with much realism and with the eyes molded in color. The first evidence (around 6500 BC) of the use of plaster is found in the sculptures discovered in the Ain Ghazal area of Jordan.
The fire imparted the required dehydration to the mineral and all that was Subsequent excavations (1983) left was a rain and a tread on it. brought to light a total of seven Quickly the molded material took the specimens which were dated to around 6500 BC. form of a hard and insoluble crust. Plaster, moreover, having the advantage of whiteness over clay, was also used as a decorative coating in relief.
4
The most important achievement of the period was the use of plaster as an imprinting material.
These seven heads should be regarded as the first true funerary portraits.
The most important evidence of the event was also located in the same place. The next find came from Susa and was much younger (2nd millennium BC). It is an independent portrait found in a tomb resting next to the deceased. Hedi Slim, excavation director at El Jem, Tunisia, found the workshop of a 3rd century AD cast craftsman. In it he found a sufficient number of molds—casts of human faces and animals.
One male and one female were found, of particular interest. The male cast had faithfully reproduced every detail of the face of the deceased (up to behind the ears). It is obvious that the face had been smeared with oil to perfectly capture the beard, moustache, hair and closed eyes due to the deceased's condition and to prevent the fluid plaster from sticking. The other is a female cast whose death mask has not been found. The retouching she has received, the open eyes, and the arranged hair leave room to think that she was ready to receive wax and go for casting. In any case, finds of mortuary portraits in plaster are few, and there are none made of wax (because of its perishability). The ancient Egyptians, as early as the 3rd millennium, knew the process of burning gypsum in open furnaces and pulverizing it.
They then mixed it with water and used it as a binding material in the joints of the boulders of their monuments. Theophrastus (372–287 BC) in his On Stones precisely describes the preparation of gypsum as it was done in his time in the region of Syria and Phoenicia. Our knowledge of antiquity is supplemented by written evidence from Theophrastus and Pliny (23 AD–79 BC). They give us a very clear picture of how, with the assistance of a modelmold, we passed from funerary portraits to sculptures with the molding of the dead and the reproduction of the funerary mask. From Pliny we have also learned how, in the 4th century BC, the sculptor Lysistratus of Sicyon (brother of the more famous sculptor Lysippus) used plaster for direct casting from a human face to achieve greater realism.
According to Pliny, Lysistratus was the first to think of pouring wax into the mold (a technique that led to the casting of bronze by the "indirect method of lost wax"). In doing so, he was the first to impose the process of producing brass or bronze sculpture as we know it today: template, mold, wax, bronze. He was also the first to move from idealized sculpture to realistic portrait. It is very likely that the use of plaster casts, despite Pliny's evidence, had begun much earlier than the 4th century BC. In Amarna, Egypt, plaster casts were found dating to about a thousand years earlier.
The History of Copper The use of metals has been integral According to the Roman historian to the development of human civiliza- Pliny the Elder, the origin of the word tion. metal is due to the coexistence of similar minerals in gold or silver deHumanity's first contact with metals posits: The Greek μετ’ άλλων, or met dates back to the Stone Age allon, means "with other." (between the 9th and 7th millennia). These metals are indigenous, i.e., The seven known metals of antiquity often found freely on Earth's surface. are gold (6000 BC), copper (5000BC), silver (4000 BC), lead The real age of metals, however, (3500 BC), tin (1750 BC), iron (1500 began when humans succeeded in BC), and mercury (750 BC). extracting metals from their ores, melting them, and casting them into With the exception of lead and tin, molds. they were found in their native state (they exist in nature in an elemental It is no accident, therefore, that their state as minerals). names are used to describe the epochs that followed the Neolithic The excellent mechanical properties period. of these metals helped in the manufacture of tools, hooves, utensils, jewThe Bronze Age was from 5000 to elry, and works of art. 3000 BC, the Craton Age from 3000 to 1000 BC, and the Iron Age from The ancients also found that copper 1000 BC to the present. could be shaped by forging.
They then heated the copper (annealing) to make it even more malleable while giving it an extra hardness, properties important for the manufacture of early tools and weapons. Copper, a highly plastic metal, could even be cold-forged to a satisfactory hardness. The discovery of copper alloys further improved the properties of the individual elements. For example, the fusion of tin with copper gave an alloy that had superior properties to copper or tin in both forming and casting. By the time they reached the high levels of the classical period, the craftspeople of the time, over the course of 4000 years, had managed to solve a number of problems related to the discovery of mines, mining, ore dressing, and smelting.
5
A prerequisite for the development of metallurgy was the development of pyrotechnology, which was facilitated by knowledge of handling fire for use with ceramics. Already since the Stone Age, humans had been using open and later closed kilns to fire ceramics.
Archaeological research into the mining technology of the ancients has identified and highlighted the way the galleries were opened and the excavation tools that were used (printing presses, axes, etc.).
Arsenic content of about 8% gives the alloy maximum workability, which the ancient craftsperson seems to have known very well. In this proportion, the alloy shows very good ductility and easy shaping by either cold- or hot-forging.
The dimensions of the galleries were very limited, with steps and slots to facilitate the movement of workers From the beginning of the 2nd millenand cavities in the walls for the placenium, the use of tin in the production Since the 7th millennium BC and the of alloys gradually began to prevail. first finds in Asia Minor, knowledge of ment of lamps. metal processing has been constantTo this day, impressions of the chis- The reasons for abandonment of arly evolving and expanding. els can still be seen on the walls. Ob- senic are possibly the transition of viously, the mines contained more mining from arsenic-bearing to nonIt extends from the Babylonians, metals than the ancient miners knew arsenic-bearing ore deposits and the Egyptians, Greeks, Romans, Arabs, or cared about. difficulty of controlling the proportion and European alchemists to the preof arsenic in the alloy due to its volasent day. tility and toxicity. In the middle of the 4th millennium, the use of copper in the form of an From the 4th millennium BC onward, the metallurgical knowledge of alloy began. The metals used to alloy While arsenic-rich copper ores and copper were arsenic, tin, and zinc. native arsenic are quite common gecopper, which began in what is now ologically, cassiterite (tin oxide) is a Iran, spread westward. The reason is to improve the meparticularly rare metal. chanical strength of the metal. The In the 3rd millennium, it reached the first alloys contained arsenic (1%– The world's tin mining areas are few Aegean Sea, Britain in the 2nd mil5%) and were widespread in Syria, and well known: China, Nigeria, lennium BC, and then eastward via northwest Iran, Cyclades, and Crete. Cornwall, Saxony-Bohemia, and esIndia to China in the 2nd millennium pecially Malaysia. BC. Arsenic was used mainly in the 3rd millennium BC and was abandoned The oldest bronze finds date back to Prehistoric copper ore mines and in the 2nd millennium, when the easiaround 3500 BC and come from processing centers in the Near and ly mined arsenic-rich copper deposits Thailand (Bann Chiang) in the East Middle East have been identified at began to run out. and Near East (Tepe Giyan and Kozlu in Asia Minor, and at Cyprus, Navahand of Western Iran). Palestine and Timna in the Sinai Arsenic is commonly found in arsenic Peninsula. -rich copper ores as enargite or tenIn the same period, we have finds in nadite. the wider Aegean region in parts of Zinc is also found in copper ores. present-day Bulgaria (Chernykh). The copper ores of Cyprus and IreAccording to the relevant literature, land contain significant zinc. most scholars accept that an arsenic If, for Thailand or China, the problem concentration of up to 2% is probably of finding tin was solved due to the In the Balkans we have coper in due to the use of arsenic-containing existence of deposits in their region, Aibunar and Burgas in Bulgaria and ores. Above 2% should be considfor the Near Eastern regions, Egypt in Rudna Glava in Yugoslavia. ered intentional contamination. and the Eastern Mediterranean, it remains unknown where they obAn important mine, especially for the In contrast to arsenic, the use of tin tained tin from. Romans, was that of Rio Tinto in to produce alloys was intentional Spain. since no tin-doped copper ore is For the Aegean region, from the Myfound in nature. cenaean period onward, we have the From the point of view of ancient writfirst indications of contacts be- tween ers, there are no reports of copper The presence of tin in copper alloys, Cornwall and Greece. Herodotus remining in Greece, but there are rein a proportion of 8%, like arsenic, fers to the Cassiterides ("Tin Isports, such as those of Herodotus, gives equivalent properties in terms lands"). about the gold and silver mines of of both hardness and coldand hotThassos and Skyros and the silver working. mines of Lavrio.
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Although the production of brass objects dates back to the beginning of the first millennium in the Asia Minor region, in Greece it appears from the Roman period onwards. There are references from the 7th century BC by the Greeks to brass not for its use but as an exotic product not produced in Greece. From the 1st century BC onwards, brass was produced, first for coins and then for every object that had previously been made with bronze. The zinc content of the alloys of the period was 10-30% in zinc. Finally, from the 3rd century AD a new copper alloy containing lead, zinc and tin appeared. An alloy that has been widely used ever since. It is still in use today, called red brass, and its proportions are: 85% copper, 5% tin, 5% zinc and 5% lead. Lead was also used in ancient times as a deliberate addition to castings to improve the cast ability of the alloy. The absence of lead in wrought objects indicates that the ancient craftsman knew that even its minimal presence made forging difficult. Since the Archaic period the development of casting technology has been continuous and uninterrupted. Since the 3rd century BC we have the addition of a larger quantity of Pb lead to the statues; Pb significantly improved the ductility of the alloy.
They then moved on to the lost wax Theodore was also a great architect, technique, first direct (5th-4th century sculptor, bronze maker and seal BC) and later indirect (late 4th-2nd maker. century BC). The sculptors Roikos and Theodoros, This view was based on the evolufrom Samos, made statues of bronze tionary theory of the arts of the peri- that were hollow inside. od. This theory was based on the Together with his grandson Theologic of the continuity of technical dore, they brought about many innoprogress. vations in the arts, such as the disAccording to this theory, sculpture covery of a new method of casting began with the carving of wood becopper, known as the "lost wax" techfore moving on to stone and ending nique. with metal. Correspondingly, metal They were the first to apply bronze casting therefore began with sand casting and the first to use the staand ended with lost wax. tionary gnomon, lathe and screw in Kluge (published 1927-29), in his sculpture and are said to be the first attempt to substantiate his theory, makers of scaling keys. based it on the well-known sculpture of Heneochos at Delphi (6th century From the middle of the 4th century BC) as the most convincing example BC, as can be seen both from finds and from information from ancient of a work made by the method of writers, the indirect method began to casting in sand. spread. Very quickly, research proved that From 410, when Rome was conthe only technique used by the anquered by the Barbarians, Europe cients was that of the lost wax. went through a period of war and As early as 1955 it was proven that uncertainty. the Heneochos of Delphi was cast Mines are abandoned, metallurgical using the lost-wax method. know-how is lost, and trade in metalThe predominant method of the two lurgy ceases. We have the Dark Agof lost wax, as both archaeological es. research and modern technology show, was the direct method until the Metallurgy resurfaces in Europe after Charlemagne is crowned Emperor of Hellenistic period. the Romans in 800. From the 8th century BC there is already evidence of the use of the indirect method for small objects, such as handles, supports and decorations on boilers, tripods, etc.
From the Hellenistic period and espePliny refers to Roikos from Samos cially after the Roman conquest of who was an architect and a bronze the country, the use of brass prevails. maker (7th century BC), his son Tilekles and his grandson Theodore. The copper-zinc alloy (brass) origiAccording to Pausanias, Roikos innated in the region of Lydia (Asia vented the digestion and casting of Minor) shortly before 600 BC. copper in molds. The casting techniques during that period, according to the earliest stud- In this century the artist Glaucus inies of German archaeologists and in vented the welding of iron. particular Kurt Kluge, archaeologist, Roikos was also a pioneer in the art sculptor and foundry man, the anof bronze sculpture in Greece The cient Greeks began casting (6th bronze statue of the Night, which early 5th century BC) by imprinting stood in the temple of Artemis in their models (made of carved wood) Ephesus, was his work. in sand molds.
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To ensure that the empire's coinage needs were met, Charlemagne used Saxon captives to mine silver from the old mines of central Europe (Erzgebirge or Mineral Mountains on the Czech-German border), a source of copper, silver, lead, and zinc. With the discovery in 938 of the Rammelsberg mines in Germany came the first major source of silver, lead, and copper. This discovery caused miners to frantically search for new deposits (similar to later U.S. prospectors) and gave the opportunity to regain knowledge lost during the Dark Ages.
His successors in the new flowering of bronze sculpture in the West and its reconnection with antiquity were Michelozzo di Bartolommeo, or Michelozzo Michelozzi (1396–1472), Florentine architect and sculptor of the early Renaissance (Brunelleschi's contemporary); Lorenzo Ghiberti (1386–1455); and Donatello (1386–1466). The information we have from that period is due to V. Biringuccio and G. Agricola.
He also led a cannon foundry in Venice and later in Florence. He is remembered for his book De la Pirottechnia on the treatment of metals. He is considered the father of metal casting technology.
From the Renaissance onward, the old methods became inadequate, so miners imported techniques from the Chinese and Mauritanians.
Biringuccio was a member of the order Fraternita di Santa Barbara, and the information he gives in his book on metallurgy and military arts was held in complete secrecy.
As far as artistic bronzing is concerned, after the decline of the western Roman Empire, Byzantium continued the tradition of bronze casting until the fall of Constantinople to the Turks. Thus, from the Crusades onward, Byzantine craftsmen began to transfer their knowledge to Italy. With the fall of Constantinople, their flight to the West was completed.
The printing of De la Pirottechnia preceded Agricola Georgius’s publication of De Re Metallica by 14 years. It marks the beginning of the tradition of scientific and technical bibliography.
Agricola Georgius (Georg Bauer, 1494– 1555), his book “De Re Metallica”.
As one of the first technical manuscripts to survive from the Renaissance, it is a valuable source of information on technical practice at the time of writing.
It is structured as 10 books dealing with metals, minerals, alloys, the art of brass casting, and so on. It deThe provision of knowledge mainly scribes in detail how to make molds concerned the artistic aspect of for casting and gives details about bronze casting since the Westerners' methods of mining and the use of expertise in casting bells and canexplosives. nons was more advanced. Agricola Georgius (Georg Bauer, Andrea Pisano (1290–1348) in 1330 1494–1555), a German born in undertook the construction of the Glaushau, Saxony, became known south gate of the Florence Baptistery. as the father of mineralogy with the publication of De Re Metallica. This work was the first to be cast exclusively by Italian craftsmen He studied medical physics and (installed in 1336). Pisano also con- chemistry while working mainly in tributed to the liberation of modern mineralogy and secondarily in mathart from Byzantine influence. ematics, history, and theology.
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He was a prolific writer. His greatest book, De Re Metallica, was published a year after his death (1556) although it had been finished in 1550. It is presumed that the delay was due to his rich iconography (woodcuts took time).
Vanoccio Biringuccio (1480–1539) was an Italian metallurgist born in Siena. In his career, he was in charge of an iron mine near Siena.
By the Renaissance, mining had made little progress since Roman times. Workers were still digging galleries supported by wooden beams and hauling up minerals with hand winches.
Thus they used water mills to grind minerals, pump water from the galleries, move the bellows for the casting, and heat furnaces for the metals being forged.
In 1530, when he was appointed as a historian by the prince of Saxony, he moved to Chemnitz, the center of the mining industry, where he also worked as a doctor.
Vanoccio Biringuccio (1480 - 1539) his book 'de la Pirottechnia' on the working of metals.
The History of Synthetic Resins The history of elastomeric resins begins with the arrival of the Spanish conquistadors in America. The Mayans and Aztecs in South and Central America drilled rubber trees to obtain an emulsion from which they separated the rubber by heatcrystallization. The rubber emulsion (latex) is produced by etching the bark of the tropical tree Hevea brasiliensis. Similarly, from Southeast Asia (Malaysia) and from the sap of the tree of the Palaquium family, we obtain a type of latex, gutta-percha. The molding of gutta-percha, after its introduction in 1840, was done in molds (like thermoplastics in our time).
import samples of Brazilian raincoats also for celluloid. In 1914, after 27 into Portugal was taken to court on years of litigation, his heirs were succharges of witchcraft. cessful in obtaining justice and were compensated by Kodak with The use of rubber was nonexistent in $5,000,000. Europe until 1751, when the French Academy of Sciences' research was In 1872, Adolf von Baeyer observed published. that the condensation of phenol and In 1770, J. Priestey used rubber as a formaldehyde produced a hard resinous material. gum rubber (rubber = eraser). The word rubber was coined as the English term for natural and synthetic This observation was exploited by elastomers. the Belgian-Canadian chemist Leo Baekeland in 1907, producing the Latex has been used to produce first fully synthetic resin, phenolic molds since World War II. Synthetic resin (Bakelite). resins first appeared around 1840 with the conversion of natural prodThe invention of Bakelite marked the ucts into synthetic resins. beginning of the plastics era, and Baekeland is considered the father of An example is the vulcanization of the plastics industry. Bakelite had caoutchouc and its conversion into excellent electrical insulation and rubber (caoutchouc + sulfur = rubthermal resistance. ber).
Gutta-percha as an impression material, in the form of black or brown plates heated in water (50–70 °C), In 1838, Christian Friedrich was used by dentists. Schonbein produced the first semisynthetic material, nitrocellulose, by The collection of latex has been car- applying sulfuric acid to paper ried out since ancient times by the (cellulose). natives of Central and South America. In 1839, Charles Goodyear invented vulcanization. In 1843, Thomas HanPre-Columbian cultures, unaware of cock developed the vulcanization sulfurization (vulcanization), develprocess and produced the first solid oped organic methods with similar wheeled tires. In 1888, Dunlop inresults. vented the pneumatic tire. They mixed raw latex with various vine juices, particularly Ipomoea alba. Rubber balls have been found, especially in areas that were flooded by water. The Aztecs used these as toys. According to Bernal Diaz del Castillo, the Spanish conquerors were surprised by the bouncing of the rubber balls.
Its best-known derivatives were the electrical switches, telephone sets, and radios of the time. In 1912, Fritz Klatte discovered polyvinyl acetate, which as an emulsion was used as an adhesive in wood, paper, textiles, etc.
In 1862 the first artificial plastic was created by Alexander Parkes (parkesine) by treating cellulose with nitric acid and a solvent, nitrocellulose. Then, in 1869, John Wesley Hyatt plasticized nitrocellulose by dissolving camphor in alcohol to produce celluloid (billiard balls, piano keys, etc.).
In 1887, Hannibal Goodwin filed a patent application for celluloid in the Additionally, the Mayas made a kind form of a flexible film. Goodwin, who of rubber shoe by dipping their feet in was not a chemist, as a clergyman a latex mixture. wanted a way to project slides of Bible stories in his Sunday school clasThe indigenous peoples of Brazil were familiar with the use of latex to ses. make waterproof clothing. Kodak founder George Eastman filed a patent application in April 1889, It is said that the first European to
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In 1926, Waldo Semon developed a method for laminating PVC (polyvinyl chloride, now used in sewer pipes, gutters and roofing sheets).
It is used to produce materials such as expanded polystyrene (EPS) and extruded polystyrene (XPS) for insulation, packaging materials and many other applications. (It is known in as From 1928 onward, the technology of Styrofoam®) synthetics developed rapidly, largely to meet the needs of the coming In 1933, Carlton Ellis invented polyWorld War II. ester resins (unsaturated synthetic resins). The first synthetic rubbers were introduced (with a polymerization of acet- Acrylic glass (Plexiglas, methyl ylene-chlorine in 1932 and butadipolymethacrylate) was developed in -styrene shortly afterward) and re1928 in various laboratories by sevplaced natural rubber after 1940, eral chemists, including William when the Japanese occupied the Chalmers, Otto Röhm, and Walter Asian rubber tree plantations. Bauer. In 1931, industrial production of poly- It was first brought to market in 1933 styrene began at the IG-Farben plant by the Rohm and Haas Company in Ludwigshafen am Rhein. under the brand name Plexiglas (as well as under the trade names Lucite Its use as a foam plastic (Styrofoam) and Perspex) as a durable substitute was developed in 1949 by Fritz for glass. Stastny and his boss Rudolf Gäth at BASF (patented in 1950). Polyethylene was accidentally manufactured in 1898 by Hans von PechIn the United States, it was develmann while he was studying diazooped as Styrofoam by Ray McIntire methane. at the Dow Chemical Company (patent 1944). Polypropylene was invented in 1951 when J. P. Hogan and R.L. Banks Polystyrene (polyphenylethene) is an polymerized propylene. aromatic hydrocarbon produced from the styrene monomer. It is solid at In 1954, Giulio Natta discovered the room temperature but melts when isotactic polypropylene, which had heated and becomes solid again great commercial application. when cooled. Teflon was discovered in 1930 by It was accidentally discovered in DuPont and has been on the market 1839 by Eduard Simon, who noticed since 1949. that the resin of the Styrax tree, which he called styrene, polymerized Polylactic acid is a biodegradable after a few days into a gel form which thermoplastic aliphatic polyester he called styroloxyd (styrene oxide). made from renewable sources such as corn starch (in the United States), The Styrax tree (also called Astyrax, tapioca, or starch (in Asia), or sugarAstrakia, or Wild Cypress) grows in cane (rest of the world). It is one of temperate regions (Greece, Asia Mi- the materials used in 3D printing. nor, and Lebanon). In 1937, Otto Bayer and his colIn 1941, researchers at the Dow leagues discovered polyurethanes, Chemical Company produced polywhich were polymerized by polyconstyrene foam using Carl Georg densation and had some advantages Munters's invention. over existing plastics.
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They became commercially prevalent in 1952, and in 1954 the production of polyurethane foam began. In 1939, Dr. Pierre Castan discovered epoxy resins. The basic raw material for producing epoxy resin is oil. In 1942, Harry Wesley Coover discovered cyanoacrylates, the application of which he completed in 1951. The best-known trade names for cyanoacrylate adhesives are Loctite, Eastman and Permabond. F. S. Kipping was a pioneer in the study of organic compounds in silicones. He coined the term silicone in 1901. From 1890 to 1940, he published 51 papers on the subject. In about 1930, J. F. Hyd began to study the chemistry of silicone structure and compounds. In 1943, Dow Corning began researching and manufacturing organosilicone compounds. In 1946, they begin to gain industrial and commercial value. The same year, General Electric began producing silicone polymers, and in 1956 Union Carbide began also. In 1953, within a week of each other, Daniel Fox and Hermann Schnell invented polycarbonates. These substances are known by the trade name Lexan and used to manufacture CDs and DVDs.
The Mold or Cast Terminology Negative (cast): the malleable mass upon which a form can be imprinted.
Mold, cast, form, or matrix: the negative imprint of the form of a solid body, produced mainly for the manufacture of faithful likenesses of it.
Positive (mold): the most common reference to the faithful likeness of a solid body which has been made by injecting soft matter (which then solidifies) into the cavity of another negative likeness.
A structure intended for casting a fluid material which, when set, will take its shape and then be removed.
Pattern or model: that which serves as an example for reproduction, for making copies of any person or object, used as a specimen to create something new (posed as a model to painters.
Synonyms of cast are printing, impression and negative or positive (as a clarification).
Object and Molding Materials Any three dimensional object can be reproduced through molding.
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For artists the cast is the means of producing a work of art, and for conservators it is the means of restoring a work of art, while for decorators it is the means of producing threedimensional decorative elements, and, finally, for technicians and engineers it is used to produce parts, tools, and devices and for many other applications. Marble sculpture molding (fig. 1, 2).
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Extraction from ancient artwork (fig. 3-4) for reproduction of copies.
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Casting with elastomeric silicone and plaster from a plaster model (plaster replica of an ancient one; figs. 5–7).
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Clay molding of a plaster mold for the reproduction of a ceramic replica (figs. 8–11).
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Mold (ceramic shell or investment) for casting brass sculpture (fig. 12). The wax cast (fig. 13a) the ceramic shell (investment), half-opened after casting the metal (fig. 13b ) and the final casting product (fig. 13c).
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15 Free model construction with clay and its molding with plaster. We consider free model-making to be that which is done on the basis of the image in the artist's mind and not on the basis of what they see in a posed model (figs. 14–15).
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The model can be made of any material (plaster, Styrofoam, wax, stone, wood, metal, etc.). Fig. 16 shows a hard-material model.
The Prototype or Model as an Object of Molding The molding processes, media and materials relevant to Let's not forget that even carving in marble, passes indiartists, art conservators, modelers and decorators are rectly through molding, when it is based on a plaster the subject matter of this textbook. model (preform product). The process of molding starts with the model and ends with its reproduction in the same or another material.
The model is made from either something we see or something we imagine.
The sculptor has naturally, the comfort and ability, to start from the construction of the model and through molding, to reach the completion of the work, with whatever material he has predetermined.
In either case the preform will act as the model on which the impression or molding, or casting, will be made. The template is in a sense a molding, a combination of mental and manual work. The sculptor casts the model by eye and impresses it by hand on the model.
Jugular notch The central point around which all other points are mentioned
The measurable sizes of the space are occupied by a geometric shape. In this sense, there is the dimension of length, which is the distance from point to point; of width, which is a perpendicular distance to length (thus giving the concept of a plane); and of height, which is the perpendicular distance to a plane and is identified as the third dimension of solids and space. From this it follows that space has three dimensions: length, width and height. We use these dimensions to move from the model to the template.
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