Processes + Stock
Contents
Lithography Gravure Screen Print Flexography Digital Print Pad Printing + Six Colour Foil Blocking Embossing/Debossing + Spot/ UV Varnish Weight + Finish Laid paper + Wove paper
Contents
Contents
1-2 3-4 5-6 7-8 9-10 11-12 13-14 15-16 17-18 19-20
Lithographic (offset) printing utilizes the principle that water and grease do not mix. The image area of the plate is treated with a greasy medium. Then the plate is dampened with by rollers then inked. The ink adheres to the greasy image but not the dampened areas. The paper is moved into position over the plate and then the plate and paper are run through the press. Lithographic has a planographic (flat). The whole surface has both ink and water with the addition of alcohol to aid dispersion.
Lithography
Lithography
Lithography first used smooth stone slabs to get a printing surface and this method is still used today for limited editions of fine art prints. The next development in printing came with metal plates which could be curved around metal cylinders to allow the use of rotary press. Finally the “offset� principle was developed. Where Lithography is used, it is nearly always as Offset. Meaning the inked image on the metal plate is offset (printed) onto a rubber blanket wrapped around a rotating metal cylinder. The image is then transferred from that blanket onto the paper. The reason for the rubber plate is because it is less abrasive to the plate then paper.
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Advantages 1. Good reproduction of detail and photographs 2. Cheap printing surface 3. Fast make-ready 4. Rubber blanket enables the use of a wide range of papers
PLATE CYLINDER
Lithography
Lithography
DAMPENING ROLLERS
INKING ROLLERS
OFFSET CYLINDER
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IMPRESSION CYLINDER
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Disadvantages 1. Colour variation due to problems with ink/water 2. Dampening can cause paper stretch or warping after binding 3. Dense ink coverage difficult to achieve 4. Fixed cut-off of weboffset restricts available
The ink is very thin and being spirit based dries through evaporation in a heated tunnel immediately after being printed. Most Gravure is done with web-feed machines. Running speeds of up to 50,000 impressions per hour. Typical jobs generally include magazines or catalogs very large runs. Printing is from a cylinder rather then a plate which allows speed. Gravure is also used for some kinds of packaging, printing on cellophane, decorative laminates and wallpaper.
“50,000 impressio per hour� Gravure
Gravure
Gravure is a modern day version of the intaglio process. This means that the printing image is recessed (indentation) into the cylinder with tiny hollows on a copperplated plate cylinder. The indentation vary in depth so they will leave a required amount of ink on the various parts of the printed image. The non-image area is wiped free of ink with a doctor blade. Ink is then deposited on the paper from the indentations.
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PRINTING CYLINDER Impression roller
ons FORM CYLINDER BLADE
Gravure
Gravure
INK TRAY
Advantages 1. Simple printing method and press mechanism 2. Can maintain consistent colour 3. High speed 4. Straightforward drying by evaporation 5. Good results obtainable on cheaper paper
Disadvantages 1. High cost of cylinders 2. Viable only for long runs 150,000+ 3. Longer lead times than offset 4. High costs of proofs, if press proofs needed 5. High cost of corrections for reprints, as cylinder
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A synthetic fibre which used to be silk hence the name ‘silk screen’ is stretched across a wooded or metal frame. The fibre is covered with a UV sensitive paint/ink which is left to dried in a dark room or somewhere out of the way of UV light. A stencil/artwork can then be placed onto the screen on top on the UV sensitive fibre. The screen along with the artwork placed in a UV light box and ‘exposed’. Exposing the frame allows the UV sensitive ink to
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Advantages 1. Can print a heavy film of ink 2. Economical for short runs (Even below 100 copies) 3. Can print on virtually any materials
Disadvantages 1. Difficult to achieve fine detail 2. Very low screen halftone 3. Low output qualities 4. Drying requirements
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become delicate where is has been exposed to UV light. When rinsed with a hose or jet wash crumbles off the frame leaving the UV paint which was hidden by the artwork/stencil. Ink is then placed onto the frame and pushed through the fibre onto paper using a squeegee. The paper is laid onto a flat vacuum table. The vacuum holds the paper still. The frame can be placed directly onto the paper or it can be fixed into a set position using a holding which is fitted to the ‘bed’
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Flexography
Flexography
on cellophane, plastics and metallic foils. It is generally used to produce some of the cheaper magazines and newspapers. A good proportion of newspapers are printed using this method as the inks doesn’t suffer the balance of water and ink. The ink dries instantly and doesn’t come off on the hands of the newspaper reader. This method of printing is ideal for short runs of prints, colour and black and white work. Unlike most other printing techniques it doesn’t require film or a plate to be made which makes the start up process cheaper. Although the start up cost is cheaper the cost per print is higher then offset litho.
“Engraved etchings that hold the ink”
DOCTOR BLADE
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Flexography
PRINTINEGR CYLIND
ANILOX ROLLER
FOUNTARIN ROLLE
INK
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Flexography
N IMPRESDSEIOR CYLIN PLATE CYLINDER
Flexography is the process that is a derivative of letterpress, using flexible photo polymer plates and thin, fluid inks (often now water-based rather than spirit-based) that dry by evaporation (sometimes assisted by heat) The image is raised as in the conventional form of letterpress printing. Most flexographic printing presses are webfed because of the nature of the products they are usually employed to print. Ink is applied to a plate by a metal roller; "anilox" roller, this roller has engraved etchings that hold the ink and transfer it onto the flexible plate for printing. Many machines are multi colour presses, for four-colour work. Mainly used for packaging printing
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This method of printing is ideal for short runs of prints, colour and black and white work. Unlike most other printing techniques it doesn't require film or a plate to be made which makes the start up process cheaper. Although the start up cost is cheaper the cost per print is higher then offset litho.
Digital Print
Digital Print
Digital printing uses files such as PSD, JPEG etc transferring the image digitally to the printer, this technique of printing has allowed both ultra-short run reprinting and "print on demand"- Example would be offset litho needs a minimum run of around 500 in order to be economical.
With digital printing the publishers can produce order of one print which can be printed quickly. Digital print quality is general inferior to offet-litho especially when the job has large areas of flat tints or solid colours. However this is rapidly changing as technology is constantly moving forward fast and the price of digital print is reducing.
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Digital Print
Digital Print
Advantages 1. Economical for short runs (500 or less) 2. Enables personalization of data 3.No film or plate cost 4. Shorter lead time 5. Large formats possible with ink-jet printing
Disadvantages 1. Quality of some digital printers is inferior to offset. 2. Consumerables (toner/paper)
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SOLVENTS EVAPORATE FROM THE INK
Pad Printing
PAD DEPOSITS TACKY INK ONTO SUBSTRATE
Pad printing is used for printing on otherwise impossible products in many industries including medical, automotive, promotional, apparel, and electronic objects, as well as appliances, sports equipment and toys. It can also be used to deposit functional materials such as conductive inks, adhesives, dyes and lubricants.
Pad printing is a printing process that can transfer a 2-D image onto a 3-D object. This is accomplished using an indirect offset (gravure) printing process that involves an image being transferred from the solid plate via a silicone pad onto a substrate (stock/ material).
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Pad Printing
PAD PICKS UP TACKY SURFACE OF INK
SOLVENTS EVAPORATE FROM THE INK AS THE PAD MOVES TO THE PRINTPOSITION
Six Colour
Six Colour
Hexachrome is an ultra-high fidelity sixcolor process printing system developed by Pantone, Inc. Hexachrome adds orange and green to the traditional CMYK inks for a larger and more vibrant gamut, or color range. However, such alternate colour systems still rely on color separation, half toning and lithography to produce printed images. Accurately reproducing a wide range of both vibrant and subtle colors that can be defined and displayed on computer monitors which previously could not be duplicated in print.
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Foil Blocking
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Foil Blocking
Foil bloc king oil s tam , ping stam , hot ping prin , f oil i ting m & le af im prin ting .
The stamping process is a mechanical one- a heated die imposes the foil onto the printing surface. Registration can be a bit off from hit to hit. Type sizes should stay above 8 point and lines should be no thinner than 2 points. Foils tend to fill in tight areas, such as tightly kerned type or lines that are closely spaced; generally a good idea to use in more open areas. Smooth, coated stocks work best for foil stamping. Uncoated or textured surfaces present an irregular surface that may disrupt and break up the foil. Large areas of stamping can bubble on highly coated stock if the chemistry between the two layers is not carefully considered. Also foil blocking on top of coatings or inks with high wax levels will also cause the foil to adhere improperly. Aqueous and other wax-free coatings are the best for using underneath foils; ask an experienced foil stamp supplier for guidance on getting the most effective results. Some foils can scratch easily, especially in large flat areas, so make sure the clients are aware the stamped surface could become marred with use.
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Foil Blocking
Foil Blocking
Foil blocking also called foil stamping, hot stamping, foil imprinting and leaf imprinting - uses a heated die strike to apply a colored, clear, metallic, matte, pearlescent, holographic, or otherwise tinted foil to another surface. Foils can be opaque or semitransparent. The process can be combined with embossing for a dimensional effect; applied on top of flat printed graphics for a bit of shine or extra emphasis; or used alone to create its own effect.
Embossing/Debossing Embossing/debossing and de-bossing takes printing into a third dimension. Paper is pressed between two molds called a die, that sculpt its fibers by as much as 1/8 of an inch. Images higher than the rest of the paper are embossed; images lower are de-bossed. Both are produced under heat to assure fine detail.
Embossing/Debossing
Heat also makes the images smooth and shiny. Embossed impressions made without having to register over a previously printed image are said to be blind embossed. Blind impressions cost less then impressions over ink because press operators don't have to register dies precisely.
Dies are made from either magnesium or brass.
You should not try to use lines that are so fine that paper doesn’t press into them. Deep dies need beveled edges to avoid cutting the paper. And beveled edges optically reduce the size of the images, so prepare the original artwork slightly over sized.
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The varnish is applied to highlight discrete areas of a printed design, both visually and by imparting a different texture. The effect of spot UV can be maximised when applied over Matt-lamintated printing.
Spot/UV varnish is a clear liquid that is applied like ink and cured instantly with ultraviolet light. It can provide either a gloss or matt coating. Increasingly, UV varnish is used as a pot covering to highlight a particular image because it provides more shine than varnish.
Spot/UV Varnish
Spot/UV Varhish
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Paper is mostly defined by its weight using gsm (grams per square meter) or g/m2; This is called grammage. Photocopier papers are usually around 80 gsm; letterheads and pamphlets, around 110 gsm and posters, around 170 gsm; lightweight covers.
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Weight
Weight
Weight (gsm)
finish: gloss/silk/matt, coated or uncoated Commercial printers commonly distinguish between coated and uncoated paper.
“Uncoated paper is not necessarily cheaper than coated.� The surface of the paper can be calendered to obtain a higher sheen. A coated paper can be matte or glossy. Uncoated paper can be calendered. A glossy paper gives a good reproduction of image and colour, while text readability is poor because of distracting reflections. Matte and/or uncoated paper is generally more suitible for readability, the texture is smooth but non-reflective, which means that the paper is treated with this coating will produce prints with a combination of high image quality and readability.
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Finish
Finish
Coated paper can be further devided into additional categories depending on the amount of coating it has: lightly coated, medium coated, highly coated or art paper. Coated paper has a smoother surface which gives it a higher printing quality. Examples include brochures and high culture magazine covers. Examples of uncoated papers include stationary, photocopying and pages of paper back books.
There are basically two types of paper - wove and laid. A wove paper is produced on a closely woven mold or screen and shows no impression from the mesh of the screen.
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Laid Paper
Laid Paper
This page is printed on Laid paper!
This page is printed on Wove paper!
Wove Paper
Wove Paper
20 A laid paper is produced on a coarser screen or mold supported by wires which unlike wove paper is textured.