Friday, June 19, 2009

18) HISTORY OF PRINTING

The history of printing began as an attempt to make easier and reduce the cost of reproducing multiple copies of documents, fabrics, wall papers and so on. Printing streamlined the process of communication, and contributed to the development of commerce, law, religion and culture.



1- WOODBLOCK PRINTING
Woodblock printing is a technique for printing text, images or patterns used widely throughout East Asia and originating in China in antiquity as a method of printing on textiles and later paper. As a method of printing on cloth, the earliest surviving examples from China date to before 220, and from Egypt to the 4th century. Ukiyo-e is the best known type of Japanese woodblock art print. Most European uses of the technique on paper are covered by the art term woodcut, except for the block-books produced mainly in the fifteenth century.


Yuan Dynasty woodblock edition of a Chinese play



The use of round "cylinder seals" for rolling an impress onto clay tablets goes back to early Mesopotamian civilization before 3,000 BCE, where they are the most common works of art to survive, and feature complex and beautiful images. In both China and Egypt, the use of small stamps for seals preceded the use of larger blocks. In Egypt, Europe and India, the printing of cloth certainly preceded the printing of paper or papyrus; this was probably also the case in China. The process is essentially the same - in Europe special presentation impressions of prints were often printed on silk until at least the seventeenth century.


1.1- In China
The earliest woodblock printed fragments to survive are from China and are of silk printed with flowers in three colours from the Han dynasty (before 220 CE). The earliest Egyptian printed cloth dates from the 4th century.

It is clear that the Chinese were the first by several centuries to use the process to print solid text, and equally that, much later, in Europe the printing of images on cloth developed into the printing of images on paper (woodcuts). It is also now established that the use in Europe of the same process to print substantial amounts of text together with images in block-books only came after the development of movable type in the 1450s.


1.2- In the Islamic world
Block printing, called tarsh in Arabic was developed in Arabic Egypt during the 9th-10th centuries, mostly for prayers and amulets. It is unclear whether the print blocks were made from metal or wood or other materials. This technique, however, appears to have had very little influence outside of the Muslim world. Though Europe adopted woodblock printing from the Muslim world, initially for fabric, the technique of metal block printing was also unknown in Europe. Block printing later went out of use in Islamic Central Asia after movable type printing was introduced from China.


1.3- In Europe
Block printing first came to Christian Europe as a method for printing on cloth, where it was common by 1300. Images printed on cloth for religious purposes could be quite large and elaborate, and when paper became relatively easily available, around 1400, the medium transferred very quickly to small woodcut religious images and playing cards printed on paper. These prints were produced in very large numbers from about 1425 onwards.

Around the mid-century, block-books, woodcut books with both text and images, usually carved in the same block, emerged as a cheaper alternative to manuscripts and books printed with movable type. These were all short heavily illustrated works, the bestsellers of the day, repeated in many different block-book versions: the Ars moriendi and the Biblia pauperum were the most common. There is still some controversy among scholars as to whether their introduction preceded or, the majority view, followed the introduction of movable type, with the range of estimated dates being between about 1440–1460.

The volume of Joseph Needham's Science and Civilization in China dealing with Paper and printing has a chapter that suggests that "European block printers must not only have seen Chinese samples, but perhaps had been taught by missionaries or others who had learned these un-European methods from Chinese printers during their residence in China.", but he also admitted that the "only evidence of European printing transmitted from China is a lack of counterevidence". However, paper itself was needed for the printing process and this came to Europe via trade with the Arabs from China. Historians acknowledge that paper indeed came from China without which printing would have been impossible, however, there is less direct evidence of the influence of printing technology from Asia and its influence on European printing technology.


2- STENCIL
Stencils may have been used to color cloth for a very long time; the technique probably reached its peak of sophistication in Katazome and other techniques used on silks for clothes during the Edo period in Japan. In Europe, from about 1450 they were very commonly used to colour old master prints printed in black and white, usually woodcuts. This was especially the case with playing-cards, which continued to be coloured by stencil long after most other subjects for prints were left in black and white. Stenciling back in the 2600 BC's was different. They used color from plants and flowers such as indigo (which extracts blue). Stencils were used for mass publications, as the type didn't have to be hand-written.


3- MOVABLE TYPE
Movable type is the system of printing and typography using movable pieces of metal type, made by casting from matrices struck by letterpunches.

Around 1040, the first known movable type system was created in China by Bi Sheng out of porcelain. Metal movable type was first invented in Korea during the Goryeo Dynasty (around 1230). Neither movable type system was widely used, one reason being the enormous Chinese character set.


A case of cast metal type pieces and typeset matter in a composing stick


It is traditionally summarized that Johannes Gutenberg, of the German city of Mainz, developed European movable type printing technology around 1439 and in just over a decade, the European age of printing began. However, the details show a more complex evolutionary process spread over multiple locations. Also, Johann Fust and Peter Schöffer experimented with Gutenberg in Mainz.

Compared to woodblock printing, movable type page-setting was quicker and more durable. The metal type pieces were more durable and the lettering was more uniform, leading to typography and fonts. The high quality and relatively low price of the Gutenberg Bible (1455) established the superiority of movable type, and printing presses rapidly spread across Europe, leading up to the Renaissance, and later all around the world. Today, practically all movable type printing ultimately derives from Gutenberg's movable type printing, which is often regarded as the most important invention of the second millennium.

Gutenberg is also credited with the introduction of an oil-based ink which was more durable than previously used water-based inks. Having worked as a professional goldsmith, Gutenberg made skillful use of the knowledge of metals he had learned as a craftsman. Gutenberg was also the first to make his type from an alloy of lead, tin, and antimony, known as type metal, printer's lead, or printer's metal, which was critical for producing durable type that produced high-quality printed books, and proved to be more suitable for printing than the clay, wooden or bronze types used in East Asia. To create these lead types, Gutenberg used what some considered his most ingenious invention, a special matrix wherewith the moulding of new movable types with an unprecedented precision at short notice became feasible. Within a year of printing the Gutenberg Bible, Gutenberg also published the first coloured prints.

The invention of the printing press revolutionized communication and book production leading to the spread of knowledge. Rapidly, printing spread from Germany by emigrating German printers, but also by foreign apprentices returning home. A printing press was built in Venice in 1469, and by 1500 the city had 417 printers. In 1470 Johann Heynlin set up a printing press in Paris. In 1473 Kasper Straube published the Almanach cracoviense ad annum 1474 in Kraków. Dirk Martens set up a printing press in Aalst (Flanders) in 1473. He printed a book about the two lovers of Enea Piccolomini who became pope Pius II.In 1476 a printing press was set up in England by William Caxton. Belarusian Francysk Skaryna printed the first book in Slavic language on August 6, 1517. The Italian Juan Pablos set up an imported press in Mexico City in 1539. The first printing press in Southeast Asia was set up in the Philippines by the Spanish in 1593. Stephen Day was the first to build a printing press in North America at Massachusetts Bay in 1638, and helped establish the Cambridge Press.

The Gutenberg press was much more efficient than manual copying and still was largely unchanged in the eras of John Baskerville and Giambattista Bodoni, over 300 years later. By 1800, Lord Stanhope had constructed a press completely from cast iron, reducing the force required by 90% while doubling the size of the printed area. While Stanhope's "mechanical theory" had improved the efficiency of the press, it still was only capable of 250 sheets per hour. German printer Friedrich Koenig would be the first to design a non-manpowered machine—using steam. Having moved to London in 1804, Koenig soon met Thomas Bensley and secured financial support for his project in 1807. Patented in 1810, Koenig had designed a steam press "much like a hand press connected to a steam engine." The first production trial of this model occurred in April 1811.



3.1- Flat-bed printing press
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 systems involved were first assembled in Germany by the goldsmith Johann Gutenberg in the mid-15th century. Printing methods based on Gutenberg's printing press spread rapidly throughout first Europe and then the rest of the world, replacing most block printing and making it the sole progenitor of modern movable type printing. As a method of creating reproductions for mass consumption, The printing press has been superseded by the advent of offset printing.

Printing press from 1811, photographed in Munich, Germany



Johannes Gutenberg's work in the printing press began in approximately 1436 when he partnered with Andreas Dritzehen—a man he had previously instructed in gem-cutting—and Andreas Heilmann, owner of a paper mill. It was not until a 1439 lawsuit against Gutenberg that official record exists; witnesses testimony discussed type, an inventory of metals (including lead) and his type mold.

Others in Europe were developing movable type at this time, including goldsmith Procopius Waldfoghel of France and Laurens Janszoon Coster of the Netherlands. They are not known to have contributed specific advances to the printing press. While the Encyclopædia Britannica Eleventh Edition had attributed the invention of the printing press to Coster, the company now states that is incorrect.



4- PRINTING HOUSES
Early printing houses (near the time of Gutenberg) were run by "master printers." These printers owned shops, selected and edited manuscripts, determined the sizes of print runs, sold the works they produced, raised capital and organized distribution. Some master printing houses, like that of Aldus Manutius, became the cultural centre for literati such as Erasmus.

Print shop apprentices: Apprentices, usually between the ages of 15 and 20, worked for master printers. Apprentices were not required to be literate, and literacy rates at the time were very low, in comparison to today. Apprentices prepared ink, dampened sheets of paper, and assisted at the press. An apprentice who wished to learn to become a compositor had to learn Latin and spend time under the supervision of a journeyman.
Journeyman printers: After completing their apprenticeships, journeyman (so called from the French "journée" for day) printers were free to move employers. This facilitated the spread of printing to areas that were less print-centred.

Compositors: Those who set the type for printing.

Pressmen: the person who worked the press. This was physically labour intensive.

The earliest-known image of a European, Gutenberg-style print shop is the Dance of Death by Matthias Huss, at Lyon, 1499. This image depicts a compositor standing at a compositor's case being grabbed by a skeleton. The case is raised to facilitate his work. The image also shows a pressman being grabbed by a skeleton. At the right of the printing house a bookshop is shown.



4.1- Financial aspects
Court records from the city of Mainz document that Johannes Fust was, for some time, Gutenberg's financial backer.

By the sixteenth century jobs associated with printing were becoming increasingly specialized. Structures supporting publishers were more and more complex, leading to this division of labour. In Europe between 1500 and 1700 the role of the Master Printer was dying out and giving way to the bookseller—publisher. Printing during this period had a stronger commercial imperative than previously. Risks associated with the industry however were substantial, although dependent on the nature of the publication.

Bookseller publishers negotiated at trade fairs and at print shops. Jobbing work appeared in which printers did menial tasks in the beginning of their careers to support themselves.

1500–1700: Publishers developed several new methods of funding projects.

1.Cooperative associations/publication syndicates—a number of individuals shared the risks associated with printing and shared in the profit. This was pioneered by the French.


2.Subscription publishing—pioneered by the English in the early 17th century. A prospectus for a publication was drawn up by a publisher to raise funding. The prospectus was given to potential buyers who signed up for a copy. If there were not enough subscriptions the publication did not go ahead. Lists of subscribers were included in the books as endorsements. If enough people subscribed a reprint might occur. Some authors used subscription publication to bypass the publisher entirely.


3.Installment publishing—books were issued in parts until a complete book had been issued. This was not necessarily done with a fixed time period. It was an effective method of spreading cost over a period of time. It also allowed earlier returns on investment to help cover production costs of subsequent installments.
The Mechanick Exercises, by Joseph Moxon, in London, 1683, was said to be the first publication done in installments.

Publishing trade organizations allowed publishers to organize business concerns collectively. Systems of self-regulation occurred in these arrangements. For example, if one publisher did something to irritate other publishers he would be controlled by peer pressure. Such systems are known as cartels, and are in most countries now considered to be in restraint of trade. These arrangements helped deal with labour unrest among journeymen, who faced difficult working conditions. Brotherhoods predated unions, without the formal regulations now associated with unions.



5- ROTARY PRINTING PRESS
A rotary printing press is a printing press in which the impressions are curved around a cylinder so that the printing can be done on long continuous rolls of paper, cardboard, plastic, or a large number of other substrates. Rotary drum printing was invented by Richard March Hoe in 1847, and then significantly improved by William Bullock in 1863.


6- INTAGLIO

Intaglio (pronounced in-TAL-yo) 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 the surface is covered in thick ink and then rubbed with tarlatan cloth to remove most of the excess. The final smooth wipe is usually done by hand, sometimes with the aid of 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.


7- LITHOGRAPHY ( 1796)



Invented by Bavarian author Aloys Senefelder in 1796, lithography is a method for printing on a smooth surface. Lithography is a printing process that 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 water. Thus, when the plate is introduced to a compatible ink and water mixture, the ink will adhere to the positive image and the water will clean the negative image. This allows for a relatively flat print plate which allows for much longer runs than the older physical methods of imaging (e.g., embossing or engraving).


An example of a 19th century lithograph depicting royal Afghan soldiers of the Durrani Empire in Afghanistan



8- CHROMOLITHOGRAPHY


Chromolithography was the first method for making true multi-color prints. Earlier attempts at polychromed printing relied on hand-coloring. The type of color printing stemmed from the process of lithography, and it includes all types of lithography that are printed in color. It replaced coloring prints by hand, and eventually served as a replica of a real painting. Lithographers sought to find a way to print on flat surfaces with the use of chemicals instead of relief or intaglio printing. Depending on the amount of colors present, a chromolithograph could take months to produce. To make what was once referred to as a “’chromo’”, a lithographer, with a finished painting in front of him, gradually built and corrected the print to look as much as possible like the painting in front of him, sometimes using dozens of layers. The process can be very time consuming and cumbersome contingent upon the skill of the lithographer.


1872 chromolithograph of roadside inn, published in Maryland



The technique for using color in printing was invented in 1796 in Germany. Considering the fact that it stemmed from lithography, there have been debates over whether chromolithography was created by Alois Senefelder, the same person who came up with printing by way of lithography. Senefelder introduced colored lithography in his 1818 Vollstaendiges Lehrbuch der Steindruckerey (A Complete Course of Lithography), and in the work, Senefelder told of his plans to print using color and he also explained the colors he wished to be able to print someday. Although Senefelder recorded ideas on chromolithography, it turns out that other countries besides Germany, such as France and England, were also heavily involved in trying to find a new way to print in color. Godefroy Engelmann of Mulhouse proved to be one of the few searching for ways to produce colored printed images when he was awarded his patent on chromolithography in July 1837. Even after Engelmann received his award, disputes over whether chromolithography was already being used continued to rise. Some sources point to the idea that chromolithography was already being used in areas of printing such as the production of playing cards.


9- OFFSET PRESS ( 1870s)

Offset printing is a widely 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 film of water, keeping the non-printing areas ink-free.


10- SCREEN PRINTING (1907)

Screenprinting has its origins in simple stencilling, most notably of the Japanese form (katazome), used who cut banana leaves and inserted ink through the design holes on textiles, mostly for clothing. This was taken up in France. The modern screenprinting process originated from patents taken out by Samuel Simon in 1907 in England. This idea was then adopted in San Francisco, California, by John Pilsworth in 1914 who used screenprinting to form multicolor prints in a subtractive mode, differing from screenprinting as it is done today.


11- FLEXOGRAPHY

Flexography (also called surface printing), often abbreviated to flexo, is a method of printing most commonly used for packaging (Labels, Tape, Bags, Boxes, Banners, Etc).



A flexo print is achieved by creating a 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 anilox roll. The print surface then rotates, contacting the print material which transfers the ink.

Originally flexo printing was basic in quality. Labels requiring high quality have generally been printed Offset until recently. In the last few years great advances have been made to the quality of flexo printing presses.

The greatest advances though 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 etch, though also by direct laser engraving.


12- PHOTOCOPIER ( 1960s)



Xerographic office photocopying was introduced by Xerox in the 1960s, and over the following 20 years it gradually replaced copies made by Verifax, Photostat, carbon paper, mimeograph machines, and other duplicating machines. The prevalence of its use is one of the factors that prevented the development of the paperless office heralded early in the digital revolution.



13- THERMAL PRINTER


A thermal printer (or direct thermal printer) produces a printed image by selectively heating coated thermochromic paper, or thermal paper as it is commonly known, when the paper passes over the thermal print head. The coating turns black in the areas where it is heated, producing an image.


14- LASER PRINTER ( 1969)


The laser printer, based on a modified xerographic copier, was invented at Xerox in 1969 by researcher Gary Starkweather, who had a fully functional networked printer system working by 1971. Laser printing eventually became a multibillion-dollar business for Xerox.

The first commercial implementation of a laser printer was the IBM model 3800 in 1976, used for high-volume printing of documents such as invoices and mailing labels. It is often cited as "taking up a whole room," implying that it was a primitive version of the later familiar device used with a personal computer. While large, it was designed for an entirely different purpose. Many 3800s are still in use.

The first laser printer designed for use with an individual computer was released with the Xerox Star 8010 in 1981. Although it was innovative, the Star was an expensive ($17,000) system that was only purchased by a small number of laboratories and institutions. After personal computers became more widespread, the first laser printer intended for a mass market was the HP LaserJet 8ppm, released in 1984, using a Canon engine controlled by HP software. The HP LaserJet printer was quickly followed by other laser printers from Brother Industries, IBM, and others.

Most noteworthy was the role the laser printer played in popularizing desktop publishing with the introduction of the Apple LaserWriter for the Apple Macintosh, along with Aldus PageMaker software, in 1985. With these products, users could create documents that would previously have required professional typesetting.



15- DOT MATRIX PRINTER ( 1970)

A dot matrix printer or impact matrix printer refers to a type of computer printer with a print head that runs back and forth on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copies and carbonless copies.

Each dot is produced by a tiny metal rod, also called a "wire" or "pin", which is driven forward by the power of a tiny electromagnet or solenoid, either directly or through small levers (pawls). Facing the ribbon and the paper is a small guide plate (often made of an artificial jewel such as sapphire or ruby) pierced with holes to serve as guides for the pins. The moving portion of the printer is called the print head, and when running the printer as a generic text device generally prints one line of text at a time. Most dot matrix printers have a single vertical line of dot-making equipment on their print heads; others have a few interleaved rows in order to improve dot density.



16- INKJET PRINTERS


Inkjet printers are a type of computer printer that operates by propelling tiny droplets of liquid ink onto paper.


17- DYE-SUBLIMATION PRINTER

A dye-sublimation printer (or dye-sub printer) is a computer printer which employs a printing process that uses heat to transfer dye to a medium such as a plastic card, printer paper or poster paper. The process is usually to lay one color at a time using a ribbon that has color panels. Most dye-sublimation printers use CMYO colors which differs from the more recognised CMYK colors in that the black dye is eliminated in favour of a clear overcoating. This overcoating (which has numerous names depending on the manufacturer) is effectively a thin laminate which protects the print from discoloration from UV light and the air while also rendering the print water-resistant. Many consumer and professional dye-sublimation printers are designed and used for producing photographic prints.


18- DIGITAL PRESS ( 1993)


Digital printing is the reproduction of digital images on a physical surface, such as common or photographic paper or paperboard-cover stock, film, cloth, plastic, vinyl, magnets, labels etc.

It can be differentiated from litho, flexography, gravure or letterpress printing in many ways, some of which are;

Every impression made onto the paper can be different, as opposed to making several hundred or thousand impressions of the same image from one set of printing plates, as in traditional methods.


The Ink or Toner does not absorb into the substrate, as does conventional ink, but forms a layer on the surface and may be fused to the substrate by using an inline fuser fluid with heat process(toner) or UV curing process(ink).


It generally requires less waste in terms of chemicals used and paper wasted in set up or makeready(bringing the image "up to color" and checking position).


It is excellent for rapid prototyping, or small print runs which means that it is more accessible to a wider range of designers and more cost effective in short runs.


19- 3D PRINTING


Three-dimensional printing is a method of converting a virtual 3D model into a physical object. 3D printing is a category of rapid prototyping technology. 3D printers typically work by 'printing' successive layers on top of the previous to build up a three dimensional object. 3D printers are generally faster, more affordable and easier to use than other additive fabrication technologies.


20- TECHNOLOGICAL DEVELOPMENTS


20.1 Woodcut
Woodcut is a relief printing artistic technique in printmaking in which an image is carved into the surface of a block of wood, with the printing parts remaining level with the surface while the non-printing parts are removed, typically with gouges. The areas to show 'white' are cut away with a knife or chisel, leaving the characters or image to show in 'black' at the original surface level. The block is cut along the grain of the wood (unlike wood engraving where the block is cut in the end-grain). In Europe beechwood was most commonly used; in Japan, a special type of cherry wood was popular.

Woodcut first appeared in ancient China. From 6th century onward, woodcut icons became popular and especially flourished in Buddhist texts. Since the 10th century, woodcut pictures appeared in inbetweenings of Chinese literature, and some banknotes, such as Jiaozi (currency). Woodcut New Year picture are also very popular with the Chinese.

In China and Tibet printed images mostly remained tied as illustrations to accompanying text until the modern period. The earliest woodblock printed book, the Diamond Sutra contains a large image as frontispiece, and many Buddhist texts contain some images. Later some notable Chinese artists designed woodcuts for books, the individual print develop in China in the form of New Year picture as an art-form in the way it did in Europe and Japan.

In Europe, Woodcut is the oldest technique used for old master prints, developing about 1400, by using on paper existing techniques for printing on cloth. The explosion of sales of cheap woodcuts in the middle of the century led to a fall in standards, and many popular prints were very crude. The development of hatching followed on rather later than in engraving. Michael Wolgemut was significant in making German woodcut more sophisticated from about 1475, and Erhard Reuwich was the first to use cross-hatching (far harder to do than in engraving or etching). Both of these produced mainly book-illustrations, as did various Italian artists who were also raising standards there at the same period. At the end of the century Albrecht Dürer brought the Western woodcut to a level that has never been surpassed, and greatly increased the status of the single-leaf (ie an image sold separately) woodcut.

20.2- Engraving


Engraving is the practice of incising a design onto a hard, flat surface, by cutting grooves into it. The result may be a decorated object in itself, as when silver, gold or steel are engraved, or may provide an intaglio printing plate, of copper or another metal, for printing images on paper, which are called engravings. Engraving was a historically important method of producing images on paper, both in artistic printmaking, and also for commercial reproductions and illustrations for books and magazines. It has long been replaced by photography in its commercial applications and, partly because of the difficulty of learning the technique, is much less common in printmaking, where it has been largely replaced by etching and other techniques. Other terms often used for engravings are copper-plate engraving and Line engraving. These should all mean exactly the same, but especially in the past were often used very loosely to cover several printmaking techniques, so that many so-called engravings were in fact produced by totally different techniques, such as etching.

In antiquity, the only engraving that could be carried out is evident in the shallow grooves found in some jewellery after the beginning of the 1st Millennium B.C. The majority of so-called engraved designs on ancient gold rings or other items were produced by chasing or sometimes a combination of lost-wax casting and chasing.

In the European Middle Ages goldsmiths used engraving to decorate and inscribe metalwork. It is thought that they began to print impressions of their designs to record them. From this grew the engraving of copper printing plates to produce artistic images on paper, known as old master prints in Germany in the 1430s. Italy soon followed. Many early engravers came from a goldsmithing background. The first and greatest period of the engraving was from about 1470 to 1530, with such masters as Martin Schongauer , Albrecht Dürer , and Lucas van Leiden.


20.3- Etching


Etching is the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal (the original process—in modern manufacturing other chemicals may be used on other types of material). As an intaglio method of printmaking it is, along with engraving, the most important technique for old master prints, and remains widely used today.


20.4- Halftoning


Halftone is the reprographic technique that simulates continuous tone imagery through the use of equally spaced dots of varying size. 'Halftone' can also be used to refer specifically to the image that is produced by this process.

The idea of halftone printing originates from William Fox Talbot. In the early 1850s he suggested using "photographic screens or veils" in connection with a photographic intaglio process.

Several different kinds of screens were proposed during the following decades, but the first half-tone photo-engraving process was invented by Canadians George-Édouard Desbarats and William Leggo Jr. On October 30, 1869, Desbarats published the Canadian Illustrated News which became the world’s first periodical to successfully employ this photo-mechanical technique; featuring a full page half-tone image of His Royal Highness Prince Arthur, from a photograph by Notman. Ambitious to exploit a much larger circulation, Debarats and Leggo went to New York and launched the New York Daily Graphic in March 1873, which became the world’s first illustrated daily.

The first truly successful commercial method was patented by Frederic Ives of Philadelphia in 1881. But although he found a way of breaking up the image into dots of varying sizes he did not make use of a ===screen===. In 1882 the German George Meisenbach patented a halftone process in England. His invention was based on the previous ideas of Berchtold and Swan. He used single lined screens which were turned during exposure to produce cross-lined effects. He was the first to achieve any commercial success with relief halftones.


20.5- Xerography


Xerography (or electrophotography) is a photocopying technique developed by Chester Carlson in 1938 and patented on October 6, 1942.

In 1937 Bulgarian physicist Georgi Nadjakov found that when placed into electric field and exposed to light, some dielectrics acquire permanent electric polarization in the exposed areas. That polarization persists in the dark and is destroyed in light. Chester Carlson, the inventor of photocopying, was originally a patent attorney and part-time researcher and inventor. His job at the patent office in New York required him to make a large number of copies of important papers. Carlson, who was arthritic, found this a painful and tedious process. This prompted him to conduct experiments with photoconductivity. Carlson experimented with "electrophotography" in his kitchen and in 1938, applied for a patent for the process. He made the first "photocopy" using a zinc plate covered with sulfur. The words "10-22-38 Astoria" were written on a microscope slide, which was placed on top of more sulfur and under a bright light. After the slide was removed, a mirror image of the words remained. Carlson tried to sell his invention to some companies, but because the process was still underdeveloped he failed. At the time multiple copies were made using carbon paper or duplicating machines and people did not feel the need for an electronic machine. Between 1939 and 1944, Carlson was turned down by over 20 companies, including IBM and GE, neither of which believed there was a significant market for copiers.

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