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NEHRU ARTS ANS SCIENCE COLLEGEDEPARTMENT OF VISUAL COMMUNICATION
PRINTING TECHNOLOGY
INTAGLIO
It is a family of printmaking techniques in which the image is incised into a surface, known as the matrix or plate. Normally, copper or zinc plates are used as a surface, and the incisions are created by etching, engraving, drypoint, aquatint or mezzotint. Collographs may also be printed as intaglio plates. To print an intaglio plate, ink is applied to the surface and then rubbed with tarlatan cloth to remove most of the excess. The final smooth wipe is often done with newspaper or old public phone book pages, leaving ink only in the incisions. A damp piece of paper is placed on top and the plate and paper are run through a printing press that, through pressure, transfers the ink from the recesses of the plate to the paper.
Intaglio techniques are often combined on a plate. For example Rembrandt's prints are referred to as "etchings" for convenience, but very often they have engraving and drypoint work as well, and sometimes no actual etching at all.
Apart from intaglio, the other traditional families, or groups of printmaking techniques are:
Relief prints, including woodcut, where the matrix is cut away to leave the image-making part on the original surface. The matrix is then just inked and printed; not wiped as described above.
Planographic, including lithography, where the image rests on the surface of the matrix, which can therefore often be re-used.
Other families have developed, especially in the twentieth century - see printmaking.
Intaglio and relief, as well as pantographic printing processes, print a reversed image (a mirror-image of the matrix), which must be allowed for in the composition, especially if it includes text.
Printing pressFor the invention and technology of movable type, see Movable type.
Printing press from 1811, photographed in Munich, Germany.
A printing press is a mechanical device for applying pressure to an inked surface resting upon a medium (such as paper or cloth), thereby transferring an image. The mechanical systems involved were probably first assembled in Germany by the goldsmith Johann Gutenberg around 1439,[1] based on existing screw-presses used to press cloth, grapes etc., and possibly to print woodcuts, which were printed in Europe before Gutenberg. Although both woodblock printing and movable type printing press technologies were already developed first in China, Korea in East Asia several hundred years earlier, Gutenberg was the first in Western Europe to develop a printing press.
Printing methods based on Gutenberg's printing press spread rapidly throughout first Europe and then the rest of the world. It eventually replaced most versions of block printing, making it the most used format of modern movable type, until being superseded by the advent of offset printing
Lithography
(from Greek λίθος - lithos, "stone" + γράφω - graphο, "to write") is a method for printing using a plate or stone with a completely smooth surface. By contrast, in intaglio printing plate is engraved, etched or stippled to make cavities to contain the printing ink, and in woodblock printing and letterpress ink is applied to the raised surfaces of letters or images. Lithography uses oil or fat and gum arabic to divide the smooth surface into hydrophobic regions which accept the ink, and hydrophilic regions which reject it and thus become the background. Invented by Bavarian author Alois Senefelder in 1796,[1][2] it can be used to print text or artwork onto paper or another suitable material. Most books, indeed all types of high-volume text, are now printed using offset lithography, the most common form of printing production. The word "lithography" also refers to photolithography, a microfabrication technique used to make integrated circuits and microelectromechanical systems, although those techniques have more in common with etching than with lithography.
The principle of lithography
Lithography stone and mirror-image print of a map of Munich.
Lithography uses chemical processes to create an image. For instance, the positive part of an image would be a hydrophobic chemical, while the negative image would be hydrophilic. Thus, when the plate is introduced to a compatible printing ink and water mixture, the ink will adhere to the positive image and the water will clean the negative image. This allows a flat print plate to be used, enabling much longer and more detailed print runs than the older physical methods of printing (e.g., intaglio printing, Letterpress printing).
Lithogrphy printing
ROTARY PRINTING PRESS
is a printing press in which the images to be printed are curved around a cylinder. Printing can be done on large number of substrates paper, cardboard, plastic. Substrates can be sheet feed or unwound on a continuous roll through the press to be printed and further modified if required (die cut, overprint varnish, embossing). Printing presses that use continuous rolls are sometimes referred to as "web presses". Rotary drum printing was invented by Richard March Hoe, and then slightly improved by William Bullock
Specific wallpaper printing machines, using mostly wooden printing cylinders
Today, there are three main types of rotary presses; offset commonly known as web offset, rotogravure, and flexo (short for flexography). While the three types use cylinders to print, they vary in their method.
Offset lithography uses a chemical process which an image is chemically applied to a plate (generally through exposure of photosensitive layers on the plate material). Lithography is based on the fact that water and oil do not mix, which enables the planographic process to work. In the context of a printing plate, a wettable surface (the non-image area) may also be termed hydrophilic and (the image area) a non-wettable surface hydrophobic.
Gravure is a process in which small cells or holes are etched into a copper cylinder which is filled with ink.
Flexography is a relief system in which a raised image is created on a typically polymer based plate.
In stamp collecting, rotary-press-printed stamps are sometimes a different size than stamps printed with a flat plate. This happens because the stamp images are further apart on a rotary press, which makes the individual stamps larger (typically 1/2 mm to 1 mm).
FLEXO GRAPHY
Flexography (often abbreviated to flexo) is a form of relief printing and is the method of printing most commonly used for packaging (labels, tape, bags, boxes, banners, etc.).
A flexographic print is made by creating a positive mirrored master of the required image as a 3D relief in a rubber or polymer material. A measured amount of ink is deposited upon the surface of the printing plate (or printing cylinder) using an engraved anilox roll whose texture holds a specific amount of ink. The anilox roller is covered with small wells that enable it to transfer ink to the printing plate evenly and quickly. The print surface rotates, contacting the print material which transfers the ink. [1]
One method of plate development uses light-sensitive polymer. A film negative is placed over the plate, which is exposed to ultra-violet light. The polymer hardens where light passes through the film. The remaining polymer has the consistency of chewed gum. It is washed away in a tank of either water or solvent. Brushes scrub the plate to facilitate the "washout" process. This method is considered "old-fashioned," but is still widely used in smaller operations, and is still taught in most high school and college flexo programs.
Originally flexographic printing was basic in quality. Labels requiring high quality have generally been printed using the offset process until recently. In the last few years great advances have been made to the quality of flexographic printing presses.
The greatest advances in flexographic printing have been in the area of photopolymer printing plates, including improvements to the plate material and the method of plate creation, usually photographic exposure followed by chemical etching, though also by direct laser engraving.
Digital direct to plate systems have dominated the industry recently with their better resolution and the ability to print four color process (or more) as well as offset. Companies like Dupont, MacDermid, Kodak and Esko have pioneered the latest technologies with advances in FAST washout and the latest screening technology, even companies who make plates in house are going to trade shops to get these high quality plates.
Laser-etched anilox rolls also play a part in the improvement of print quality. Full color picture printing is now possible, and some of the finer presses available today, in combination with a skilled operator, allow quality that rivals the lithographic process. One ongoing improvement has been the increasing ability to reproduce highlight tonal values, thereby providing a workaround for the very high dot gain associated with flexographic printing.
Flexo has an advantage over lithography in that it can use a wider range of inks, water based rather than oil based inks, and is good at printing on a variety of different materials. Flexographic inks, like those used in gravure and unlike those used in lithography, generally have a low viscosity. This enables faster drying and, as a result, faster production, which results in lower costs.
Printing press speeds of up to 600 meters per minute (2000 feet per minute) are achieveable now with modern technology high-end printers, like Flexotecnica [1], which introduced the world's first 12-color central impression (CI) drum press at Drupa 2008. Other press formats, such as in-line and stack presses, are available from Tresu and other suppliers.
Process Overview
The major unit operations in a flexographic printing operation are:
* Image preparation:images are captured by the camera, transferred to a scanner or computer.A simple proof or brown print is prepared to check position and accuracy. * Platemaking:The photomechanical plate making method begins with making an engraving, which occurs when the metal plate is exposed through a negative and processing the plate in an acid bath. The engraved plate is used to make a master which is molded * Printing: * Finishing:This is accomplished by exposing a metal plate through a negative and processing the exposed plate in an acid bath. The metal engraved plate is used to make a master which is molded out of bakelite board. The engraving is placed in a mold press. The mold is produced by applying heat & pressure to the mold material (bakelite board), which can be either plastic or glass, against the engraving under controlled temperature and pressure. The bakelite board fills the engraving on the metal plate. When its cooled you end up with a master mold for the plastic or rubber compound that will be pressed into the mold under pressure and elevated temperature to produce the flexible printing plate with raised areas that will transfer the ink.
The second method of flexo plate making is relief plates. This utilizes a solid or liquid photopolymer. The sheet of photopolymer is exposed to light through a negative. The unexposed areas are then washed away with solvent or water wash. This is fast becoming the most common method of making plates.
Flexographic Printing Process Flow Diagram
Linotype machine
From Wikipedia, the free encyclopedia
The Linotype machine (pronounced "Line-O-Type" ['laɪnəˌtaɪp]) is a "line casting" machine used in printing. The machine revolutionized printing and especially newspaper publishing, making it possible for a relatively small number of operators to set type for many pages on a daily basis. Prior to its invention in 1884, no newspaper in the world had more than eight pages.
The Linotype machine operator enters text on a 90-character keyboard. The machine assembles "matrices", which are molds for the letter forms, into a line. The assembled line is then cast as a single piece, called a "slug", of type metal. The matrices are then returned to the type magazine from which they came. The name of the machine comes from the fact that it produces an entire line of metal type at once - hence a "line o' type". This allows much faster typesetting and composition than original hand composition in which operators place down one pre-cast metal letter, punctuation mark or space at a time.
HOT TYPE COMPOSITION
mono type
Lino type
Offset printing is a commonly used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.
Ira Washington Rubel invented the first offset printing press in 1903.[1]
Offset printing advantages
Advantages of offset printing compared to other printing methods include:
Consistent high image quality. Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface.
Quick and easy production of printing plates. Longer printing plate life than on direct litho presses because there is no direct
contact between the plate and the printing surface. Properly developed plates running in conjunction with optimized inks and fountain solution may exceed run lengths of a million impressions.
The more you print, the less you pay per page, because most of the price goes into the preparation undergone before the first sheet of paper is printed and ready for distribution. Any additional paper print will only cost the client paper price (and ink), which is very minimal.
Offset printing disadvantages
Disadvantages of offset printing compared to other printing methods include:
Slightly inferior image quality compared to rotogravure or photogravure printing. Propensity for anodized aluminum printing plates to become sensitive (due to
chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly.
SCREEN-PRINTING
Screen printing 1. A printing technique that uses a woven mesh to support an ink blocking stencil. The attached stencil forms open areas of mesh that transfer ink as a sharp-edged image onto a substrate. A roller or squeegee is moved across the screen stencil forcing or pumping ink past the threads of the woven mesh in the open areas. 2. A stencil method of print making in which a design is imposed on a screen of silk or other fine mesh, with blank areas coated with an impermeable substance, and ink is forced through the mesh onto the printing surface. Also known as Silk Screening or Serigraphy.
Printing technique
A screen is made of a piece of porous, finely woven fabric called mesh stretched over a frame of aluminum or wood. Originally human hair then silk was woven into screen mesh, currently most mesh is made of man made materials such as steel, nylon, and polyester. Areas of the screen are blocked off with a non-permeable material to form a stencil, which is a negative of the image to be printed; that is, the open spaces are where the ink will appear.
The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a fill bar (also known as a floodbar) is used to fill the mesh openings with ink. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen. This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. The operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is pumped or squeezed by capillary action to the substrate in a controlled and prescribed amount, i.e. the wet ink deposit is equal to the thickness of the mesh and or
stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate (called snap-off) leaving the ink upon the substrate surface.
There are three types of screenprinting presses. The 'flat-bed' (probably the most widely used), 'cylinder', and 'rotary'.[8]
Textile items are printed in multi-color designs using a wet on wet technique, while graphic items are allowed to dry between colors that are then printed with another screen and often in a different color.
The screen can be re-used after cleaning. However if the design is no longer needed, then the screen can be "reclaimed", that is cleared of all emulsion and used again. The reclaiming process involves removing the ink from the screen then spraying on stencil remover to remove all emulsion. Stencil removers come in the form of liquids, gels, or powders. The powdered types have to be mixed with water before use, and so can be considered to belong to the liquid category. After applying the stencil remover the emulsion must be washed out using a pressure washer.
Most screens are ready for recoating at this stage, but sometimes screens will have to undergo a further step in the reclaiming process called dehazing. This additional step removes haze or "ghost images" left behind in the screen once the emulsion has been removed. Ghost images tend to faintly outline the open areas of previous stencils, hence the name. They are the result of ink residue trapped in the mesh, often in the knuckles of the mesh, those points where threads overlap. [13]
While the public thinks of garments in conjunction with screenprinting, the technique is used on tens of thousands of items, decals, clock and watch faces, and many more products. The technique has even been adapted for more advanced uses, such as laying down conductors and resistors in multi-layer circuits using thin ceramic layers as the substrate.
Stenciling techniques
A macro photo of a screenprint with a photographically produced stencil. The ink will be printed where the stencil does not cover the substrate.
There are several ways to create a stencil for screenprinting. An early method was to create it by hand in the desired shape, either by cutting the design from a non-porous material and attaching it to the bottom of the screen, or by painting a negative image directly on the screen with a filler material which became impermeable when it dried. For a more painterly technique, the artist would choose to paint the image with drawing fluid, wait for the image to dry, and then coat the entire screen with screen filler. After the filler had dried, water was used to spray out the screen, and only the areas that were painted by the drawing fluid would wash away, leaving a stencil around it. This process enabled the artist to incorporate their hand into the process, to stay true to their drawing.
A method that has increased in popularity over the past 70 years and is tremendously popular is the photo emulsion technique:
1. The original image is created on a transparent overlay such as acetate or tracing paper. The image may be drawn or painted directly on the overlay, photocopied, or printed with a laser printer, as long as the areas to be inked are opaque. A black-and-white negative may also be used (projected on to the screen). However, unlike traditional platemaking, these screens are normally exposed by using film positives.
2. The overlay is placed over the emulsion-coated screen, and then exposed with an ultraviolet light source in the 350-420 Nanometer spectrum. Other light sources do not work well. The UV light passes through the clear areas and create a polymerization (hardening) of the emulsion.
3. The screen is washed off thoroughly. The areas of emulsion that were not exposed to light dissolve and wash away, leaving a negative stencil of the image on the mesh.
Photographic screens can reproduce images with a high level of detail, and can be reused for tens of thousands of copies[citation needed]. The ease of producing transparent overlays from any black-and-white image makes this the most convenient method for artists who are not familiar with other printmaking techniques. Artists can obtain screens, frames, emulsion, and lights separately; there are also preassembled kits, which are especially popular for printing small items such as greeting cards.
Another advantage of screenprinting is that large quantities can be produced rapidly with new automatic presses (up to 1200 shirts in 1 hour).[citation needed] (The record is over 2000 shirts an hour.)
Textile screen printing machinery
screen printing
GRAVURE PRESS
Gravure may also refer to Gravure idol.
Rotogravure (roto or gravure for short) is a type of intaglio printing process, in that it involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a copper cylinder because, like offset and flexography, it uses a rotary printing press. The vast majority of gravure presses print on reels of paper, rather than sheets of paper. (Sheetfed gravure is a small, specialty market.) Rotary gravure presses are the fastest and widest presses in operation, printing everything from narrow labels to 12-feet-wide rolls of vinyl flooring. Additional operations may be in-line with a gravure press, such as saddle stitching facilities for magazine/brochure work.
In the 1930s–1960s, newspapers published relatively few photographs and instead many newspapers published separate rotogravure sections in their Sunday editions. These sections were devoted to photographs and identifying captions, not news stories. Irving Berlin's song Easter Parade specifically refers to these sections in the lines "the photographers will snap us, And you'll find that you're in the rotogravure."
In 1932 a George Gallup "Survey of Reader Interest in Various Sections of Sunday Newspapers to Determine the Relative Value of Rotogravure as an Advertising Medium" found that these special rotogravures were the most widely read sections of the paper and that advertisements there were three times more likely to be seen by readers than in any other section.
The rotogravure process is still used for commercial printing of magazines, postcards, and corrugated (cardboard) product packaging.In the latter quarter of the 19th century, the method of image photo transfer onto carbon tissue covered with light-sensitive gelatin was discovered and was the beginning of rotogravure.
GRAVURE PRESS
Gravure cylinders nowadays are typically engraved digitally by a diamond tipped or laser etching machine. On the gravure cylinder, the engraved image is composed of small recessed cells (or 'dots') that act as tiny wells. Their depth and size control the amount of ink that gets transferred to the substrate (paper or other material, such as plastic or foil) via a process of pressure, osmosis, and electrostatic pull. (A patented process called "Electrostatic Assist" is sometimes used to enhance ink transfer.)
A rotogravure printing press has one printing unit for each color, typically CMYK or cyan, magenta, yellow and key (printing terminology for black). The number of units
vary depending on what colors are required to produce the final image. There are five basic components in each color unit: an engraved cylinder (whose circumference can change according to the layout of the job), an ink fountain, a doctor blade, an impression roller, and a dryer. While the press is in operation, the engraved cylinder is partially immersed in the ink fountain, filling the recessed cells. As the cylinder rotates, it draws ink out of the fountain with it. Acting as a squeegee, the doctor blade scrapes the cylinder before it makes contact with the paper, removing ink from the non-printing (non-recessed) areas. Next, the paper gets sandwiched between the impression roller and the gravure cylinder. This is where the ink gets transferred from the recessed cells to the paper. The purpose of the impression roller is to apply force, pressing the paper onto the gravure cylinder, ensuring even and maximum coverage of the ink. Then the paper goes through a dryer because it must be completely dry before going through the next color unit and absorbing another coat of ink.
Because gravure is capable of transferring more ink to the paper than other printing processes, gravure is noted for its remarkable density range (light to shadow) and hence is a process of choice for fine art and photography reproduction, though not typically as clean an image as that of sheet fed litho or web offset litho. Gravure is widely used for long-run magazine printing in excess of 1 million copies. Gravure's major quality shortcoming is that all images, including type and "solids," are actually printed as dots, and the screen pattern of these dots is readily visible to the naked eye. Examples of gravure work in the United States are typically long-run magazines, mail order catalogs, consumer packaging, and Sunday newspaper ad inserts.
Other application area of gravure printing is in the flexible packaging sector. A wide range of substrates such as Polyethylene, Polypropylene, Polyester, BOPP etc.. can be printed in the gravure press.
Rotary press
Even as the iron press was introduced, Koenigwas working on the rotary press. The principle isto use a cylinder to roll over the printing surface,rather than pressing two flat surfaces together.The Times of London started using hispresses in 1814, and the engineering advantage ofthe process assured its ascendancy over platens,other than for small sheet work, by the end of thecentury. The key point is that the area of contactat any one time is limited to a small strip thelength of the cylinder. This much smaller area(than the full sheet being printed), means thatthe forces required are far smaller than for theplaten presses before, and while the iron platenpress seldom prints much beyond an A2 sheet(twice this one), cylinder presses were printingsheet sizes limited more by the difficulties of handlingthem, than by the presses.The most popular design of cylinder pressThe Rotary Presseventually was the “Two-rev”: the cylinder made tworevolutions for each sheet printed, one to print, andone to release the sheet while the forme was runningunder the inking rollers. In some machines the cylindermoved, in others the printing surface.Cylinder presses became established as powerwas being applied to industrial machinery, and theywere power-operated from the start. However, usingconventional type in a flat forme limited the speed ofoperation: the forme or cylinder, or both, had to reciprocate,mechanically inefficient compared to continuousrotation. Stereotyping allowed the printing surfaceto be made as a cylinder, and thus permitted therotary press, with the paper running between twocylinders, one the printing image, the other takingthe pressure. This led (with advances in papermaking)to feeding the paper through as a continuousstrip (a “web”), and today’s mass-production pressesare all of this design, web-fed rotary. An added advantagewas that the web could be fed directly toanother similar press, printing a second colour.Here the letterpress machine merges with otherprinting processes, for a lithographic, photogravure,or flexographic machine uses the same
principles, though different printing surfacesand inking methods.By early in the twentieth century, the webfedletterpress machine, sometimes the size of asmall house, made possible the rise of mass circulationnewspapers & magazines, and the paperbackbook. Where the wooden press spreadliteracy and ideas; the iron press gave the middleclasses affordable books, the poor cheap pamphlets,and fuelled the nineteenth century scientific,technical & educational revolutions inEurope; the web presses provided mass literacy,mass entertainment, mass marketing, & the riseof consumerism
Gravure printing
Cylinder preparation But let’s start with the cylinder preparation.In former times gravure cylinderswere produced with photographic filmsand etching. This was a complex processwhich needed time, raw materials andenergy and led to some chemical waste.These production steps are completely replacedby digital data handling. The finalstep of producing the cells in the surfaceof publication gravure printing cylindersis done either electromechanically by aHelio-Klischograph or else with a laser installation,etching is no longer necessary.The surface is then plated with a hardchromium layer to improve its wearingproperties. Nowadays most gravure printersbuy the necessary chromium compoundin dissolved from, which meansthat the Health and Safety aspect is substantiallyoptimized because the occurrenceof dust is no longer possible. As a5
Gravure News 166/07sideline, the surface has a higher qualitybecause continuous flow of the solutionholds the concentration of the chromiumions during the galvanisation constant.
Printing inkThe European publication rotogravureindustry uses 180 000 tonnes of ink annually(2006). This consists of 30 kt pigments,50 kt resins and 100 kt toluene.The toluene is to more than 95 % reused:this is possible because gravure uses amono-solvent system. The formation ofazeotropes (constant-boiling mixtures,which hinder purification) is not possible,so it is not necessary to distil therecovered solvent. This saves time, costand energy. The recovered pure toluenecan be reused on site or delivered backto the ink maker.The toluene amounts which escape inthe exhaust gas from the printing plantare very small. An EU Directive asks fora value below 82 mg per cubic metre ofwaste gas, which is more than compliedwith by all European rotogravure printers.Natural free radical chain processesin the atmosphere then break down thistoluene: its atmospheric half-life is,according to the World Health Organisation(WHO), 12,8 hours.Some toluene is lost as traces in theprinted products. This amount has beensignificantly lowered in recent years.This was mainly achieved though modificationof the ink composition. Thesurface of the printed ink takes slightlymore time to solidify. In this short time period, around ten milliseconds, additionaltoluene evaporates in the printingunit and is caught by the recovery system.When the printed matter leaves thecompany the toluene traces are in anycase below 0,04 %.In consequence the airborne tolueneconcentration in private homes is farbelow 260 μg per cubic metre of air:this was confirmed by a study made inFebruary 2007 by the Flemish researchinstitute VITO. The figure of 260 μg/m³is the maximum limit accepted by theWHO for private homes. At the workplace,and already including a highsafety margin, the maximum allowedconcentration is 190 mg/m³ as averageover an eight-hour working day (EUDirective), which means that the WHOlimit for private homes is 730 times morediluted. The pigments in the gravureprinting inks are synthetic, mostly basedon petrochemicals. The European PrintingInk Makers Association establishedyears ago an “Exclusion List for PrintingInk and Related Products” which excludestoxic and other very harmful materialsas ingredients. The resins of thegravure inks based approximately 80 %on natural materials, for example rosin,gum rosin, tall oil resin. The last is a byproductof chemical pulp production inthe paper industry.
PaperThe paper industry has made extraordinaryimprovements during the lastdecades to reduce the environmentalimpact of the paper production. Yearsago it seemed impossible that high qualitypublication gravure products couldbe printed on paper which contains
recycledfibres. The European publicationgravure paper manufacturers, which incidentallyare all members of ERA, managedto develop such papers. Publicationgravure papers which contain de-inkedpulp (DIP), which means recycled fibres,are available on the market and used atcustomers’ request.At the same time it was possible to reducethe paper basis weight (grammage)without losing the optical properties.Paper production was advanced, forexample in Europe elemental chlorine bleaching was replaced by other moreenvironmentally friendly oxidation methods. Water and energy consumption was reduced. The carbon dioxide balance improved through using renewableenergy sources. The recycling rate for printed matter in Europe is 55 %(2005): if the European recovered paper which is recycled outside Europe is included,the rate reaches 63 % (2005).Gravure printing
The productivity of gravure printing isvery high. Advanced presses can printon a 4,32 m wide paper web at speedsof up to 16 m/s. But even with smallerunits, the energy used per square metreof printed product is less than in alternativeprinting methods. However thisadvantage increases the longer the printrun. The saving of energy reduces thecarbon dioxide emission which is one ofthe top themes today and in the future.The main environmental advantages ofpublication gravure printing are:– the use of easily recyclableraw materials,– the usage of renewable rawmaterials,– and last but not least, theproduction of a very easilyrecyclable product. ■ JBCO2 emission in the production chain of a daily newspaperPaper manufacturePrintingNewspaper distribution( transport and warehousing)Ink productionTransport(raw materials to mill,paper to printer)Disposal(transport of waste,returns and collections)
LithographyMain article: Lithography
Artists using this technique include
George Bellows, Pierre Bonnard, Honoré Daumier, Salvador Dalí, M. C. Escher, Dulah Marie Evans, Ellsworth Kelly, Willem de Kooning, Joan Miró, Edvard Munch, Emil Nolde, Pablo Picasso, Odilon Redon, Henri de Toulouse-Lautrec, Toyen and Stow Wengenroth
La Goulue, Lithograph poster by Toulouse-Lautrec.
Lithography is a technique invented in 1798 by Alois Senefelder and based on the chemical repulsion of oil and water. A porous surface, normally limestone, is used; the image is drawn on the limestone with a greasy medium. Acid is applied, transferring the grease to the limestone, leaving the image 'burned' into the surface. Gum arabic, a water soluble substance, is then applied, sealing the surface of the stone not covered with the drawing medium. The stone is wetted, with water staying only on the surface not covered in grease-based residue of the drawing; the stone is then 'rolled up', meaning oil ink is applied with a roller covering the entire surface; since water repels the oil in the ink, the ink adheres only to the greasy parts, perfectly inking the image. A sheet of dry paper is placed on the surface, and the image is transferred to the paper by the pressure of the printing press. Lithography is known for its ability to capture fine gradations in shading and very small detail.
A variant is photo-lithography, in which the image is captured by photographic processes on metal plates; printing is carried out in the same way.
Screen-printingMain article: Screen-printing
Artists using this technique include
Josef Albers, Chuck Close, Ralston Crawford, Robert Indiana, Roy Lichtenstein, Julian Opie, Robert Rauschenberg, Bridget Riley, Edward Ruscha, and Andy Warhol.
Screen-printing (also known as "screenprinting", "silk-screening", or "serigraphy") creates bold color using a stencil technique. Stencil printing is arguably the oldest form of graphic arts.
The first time man placed his hand against a cave wall and blew ash and dried blood against it was the first time a stencil was used. Around 500 BC in Japan, artists were gluing human hair between pieces of paper to create floral stencils which were used with brushes to tamp color. The hair was later replaced with a silk mesh (hence the name “silk screen”). Stencils were even used to print the bold red crosses on the shields and cuirasses of the crusading knights, but it wasn’t until the turn of the century that silk screen printing became industrialized and was used in the printing of fabrics and textiles throughout the western world. After that, it was only a matter of time before artists such as Roy Lichtenstein, Robert Rauschenberg, and Andy Warhol began experimenting with the technique for artistic purposes.
In screen printing, the artist draws or paints an image on a piece of paper or plastic (film can also be used). The image is cut out creating a stencil (keep in mind that the pieces which are cut away are the areas that will let ink through). A screen is made of a piece of fabric (originally silk) stretched over a wood or aluminium frame. The stencil is fixed to the screen.
Modern technology uses direct and indirect photo emulsions which are UV sensitive. This means that the artist’s renderings on transparent film can be exactly reproduced on the nylon screen coated with light sensitive (UV) emulsion. The light sensitive emulsion fills in the entire screen, the transparent film upon which the artist has drawn is laid upon the screen and both are placed in the exposure unit. Where the light passes through the transparent film, the emulsion is exposed and hardens. Where the artist's markings on the film stop the light, the emulsion is NOT exposed and releases upon washing, creating a stencil on the screen that exactly reproduces the artist’s markings to the finest detail.
The screen is then placed on top of almost any substrate, paper, glass, fabric, golf balls, etc. Ink is then placed across the top length of the screen. A squeegee (rubber blade) is used to spread the ink across the screen, over the stencil, and through the open mesh onto the paper/fabric below. The screen is lifted once the image has been transferred onto the paper/fabric, which is replaced with the next, unprinted, substrate. Colors are added layer by layer and each color requires a separate stencil on a separate screen. The screen can be re-used after cleaning.
Digital printsArtists using this technique include
Istvan Horkay, Zazie (surrealist)
Digital prints refers to editions of images created with a computer using drawings, other prints, photographs, light pen and tablet, and so on. These images can be printed to a variety of substrates including paper and cloth or plastic canvas. Accurate color reproduction is key to distinguishing high quality from low quality digital prints. Metallics (silvers, golds) are particularly difficult to reproduce accurately because they reflect light back to digital scanners. High quality digital prints typically are reproduced with very high-resolution data files with very high-precision printers. The substrate used
has an effect on the final colors and cannot be ignored when selecting a color palette. The term Giclée is sometimes used to describe the process of making fine art prints from a digital source using ink-jet printing.
Digital images can be printed on standard desktop-printer paper and then transferred to traditional art papers (Velin Arch or Stonehenge 200gsm, for example). One way to transfer an image is to place the printout face down upon the art paper and rub Wintergreen oil upon the back of the print, and pass it through a press.
Digital prints that are stored and sold electronically are problematic when it comes to authorship of the print and the protection of pecuniary interests. Adobe Systems tried to overcome the digital edition problem with their Adobe Reader application.
Electronic images are truly multiple originals as they rely upon code to produce the image and every copy is actually the writing of code upon a disk or reproduction of code. Prints produced via any other medium are copies and not truly original unless a process of manual editing of the final result or plate is applied.
Sociologist Jean Baudrillard has had a large influence upon digital printmaking with theories expounded on in Simulacra and Simulation.
Foil imagingMain article: Foil imaging
In art, foil imaging is a printmaking technique made using the Iowa Foil Printer, developed by Virginia A. Myers from the commercial foil stamping process. This uses gold leaf and acrylic foil in the printmaking process.
Color
Printmakers apply color to their prints in many different ways. Often color in printmaking that involves etching, screenprinting, woodcut, or linocut is applied by either using separate plates, blocks or screens or by using a reductionist approach. In multiple plate color techniques, a number of plates, screens or blocks are produced, each providing a different color. Each separate plate, screen, or block will be inked up in a different color and applied in a particular sequence to produce the entire picture. On average about 3 to 4 plates are produced, but there are occasions where a printmaker may use up to seven plates. Every application of another plate of color will interact with the color already applied to the paper, and this must be kept in mind when producing the separation of colors. The lightest colors are often applied first, and then darker colors successively until the darkest.
The reductionist approach to producing color is to start with a lino or wood block that is either blank or with a simple etching. Upon each printing of color the printmaker will then further cut into the lino or woodblock removing more material and then apply
another color and reprint. Each successive removal of lino or wood from the block will expose the already printed color to the viewer of the print.
With some printing techniques like chine-collé or monotyping the printmaker may sometimes just paint into the colors they want like a painter would and then print.
The subtractive color concept is also used in offset or digital print and is present in bitmap or vectorial software in CMYK or other color spaces.
Protective printmaking equipment
Protective clothing is very important for printmakers who engage in etching and lithography (closed toed shoes and long pants). In the past, many printmakers did not live far past 35 to 40 years of age because of their exposure to various acids, solvents, particles, and vapors inherent in the printmaking process.
Whereas in the past printmakers put their plates in and out of acid baths with their bare hands, today printmakers use rubber gloves. They also wear industrial respirators for protection from caustic vapors. Most acid baths are built with ventilation hoods above them.
Often, an emergency cold shower or eye wash station is nearby in case of acid spillages, as well as soda ash- which neutralizes most acids. Some printmakers wear goggles when dealing with acid.
Protective respirators and masks should have particle filters, particularly for aquatinting. As a part of the aquatinting process, a printmaker is often exposed to rosin powder. Rosin is a serious health hazard, especially to printmakers who, in the past, simply used to hold their breath using an aquatinting booth.
Barrier cream is often used upon a printmaker's hands both when putting them inside the protective gloves and if using their hands to wipe plates (wipe ink into the grooves of the plate and remove excess).
Sterile plasters and bandages should always be available to treat cuts and scrapes. For example, zinc plates can be extremely sharp when their edges are not beveled.