Lithography

Lithography can be used to print text or images onto paper or other suitable material. Traditionally, the image to be printed was drawn with a greasy substance, such as oil, fat, or wax onto the surface of a smooth and flat limestone plate. The stone was then treated with a mixture of weak acid and gum arabic ("etch") that made the parts of the stone's surface that were not protected by the grease more hydrophilic (water attracting). For printing, the stone was first moistened. The water adhered only to the etched, hydrophilic areas, making them even more oil-repellant. An oil-based ink was then applied, and would stick only to the original drawing. The ink would finally be transferred to a blank sheet of paper, producing a printed page. This traditional technique is still used for fine art printmaking. In modern commercial lithography, the image is transferred or created as a patterned polymer coating applied to a flexible plastic or metal plate. The printing plates, made of stone or metal, can be created by a photographic process, a method that may be referred to as "photolithography" (although the term usually refers to a vaguely similar microelectronics manufacturing process). Offset printing or "offset lithography" is an elaboration of lithography in which the ink is transferred from the plate to the paper indirectly by means of a rubber plate or cylinder, rather than by direct contact. This technique keeps the paper dry and allows fully automated high-speed operation. It has mostly replaced traditional lithography for medium- and high-volume printing: since the 1960s, most books and magazines, especially when illustrated in colour, are printed with offset lithography from photographically created metal plates.

Lithography uses simple chemical processes to create an image. For instance, the positive part of an image is a water-repelling ("hydrophobic") substance, while the negative image would be water-retaining ("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). Lithography was invented by Alois Senefelder in the Electorate of Bavaria in 1796. In the early days of lithography, a smooth piece of limestone was used (hence the name lithography: lithos (λιθος) is the Ancient Greek word for 'stone'). After the oil-based image was put on the surface, a solution of gum arabic in water was applied, the gum sticking only to the non-oily surface. During printing, water adhered to the gum arabic surfaces and was repelled by the oily parts, while the oily ink used for printing did the opposite.

• Illustration — Lithography stone and mirror image print of a map of Munich Lithography works because of the mutual repulsion of oil and water. The image is drawn on the surface of the print plate with a fat or oil-based medium (hydrophobic) such as a wax crayon, which may be pigmented to make the drawing visible. A wide range of oil-based media is available, but the durability of the image on the stone depends on the lipid content of the material being used, and its ability to withstand water and acid. After the drawing of the image, an aqueous solution of gum arabic, weakly acidified with nitric acid is applied to the stone. The function of this solution is to create a hydrophilic layer of calcium nitrate salt, and gum arabic on all non-image surfaces. The gum solution penetrates into the pores of the stone, completely surrounding the original image with a hydrophilic layer that will not accept the printing ink. Using lithographic turpentine, the printer then removes any excess of the greasy drawing material, but a hydrophobic molecular film of it remains tightly bonded to the surface of the stone, rejecting the gum arabic and water, but ready to accept the oily ink. When printing, the stone is kept wet with water. The water is naturally attracted to the layer of gum and salt created by the acid wash. Printing ink based on drying oils such as linseed oil and varnish loaded with pigment is then rolled over the surface. The water repels the greasy ink but the hydrophobic areas left by the original drawing material accept it. When the hydrophobic image is loaded with ink, the stone and paper are run through a press that applies even pressure over the surface, transferring the ink to the paper and off the stone. • Illustration — This very early colour lithograph from 1835 uses large washes of orange and cyan with black ink providing the details. Senefelder had experimented during the early 19th century with multicolor lithography; in his 1819 book, he predicted that the process would eventually be perfected and used to reproduce paintings. Multi-color printing was introduced by a new process developed by Godefroy Engelmann (France) in 1837 known as chromolithography. A separate stone was used for each color, and a print went through the press separately for each stone. The main challenge was to keep the images aligned (in register). This method lent itself to images consisting of large areas of flat color, and resulted in the characteristic poster designs of this period. • Illustration — A lithographer at work, 1880. "Lithography, or printing from soft stone, largely took the place of engraving in the production of English commercial maps after about 1852. It was a quick, cheap process and had been used to print British army maps during the Peninsular War. Most of the commercial maps of the second half of the 19th century were lithographed and unattractive, though accurate enough."

• Illustration — Lithographic image of Bothwell Castle near Glasgow, from 1833 During the early years of the 19th century, lithography had only a limited effect on printmaking, mainly because technical difficulties remained to be overcome. Germany was the main center of production in this period. Godefroy Engelmann, who moved his press from Mulhouse to Paris in 1816, largely succeeded in resolving the technical problems, and during the 1820s lithography was adopted by artists such as Delacroix and Géricault. After early experiments such as Specimens of Polyautography (1803), which had experimental works by a number of British artists including Benjamin West, Henry Fuseli, James Barry, Thomas Barker of Bath, Thomas Stothard, Henry Richard Greville, Richard Cooper, Henry Singleton, and William Henry Pyne, London also became a center, and some of Géricault's prints were in fact produced there. Goya in Bordeaux produced his last series of prints by lithography—The Bulls of Bordeaux of 1828. By the mid-century the initial enthusiasm had somewhat diminished in both countries, although the use of lithography was increasingly favored for commercial applications, which included the prints of Daumier, published in newspapers. Rodolphe Bresdin and Jean-François Millet also continued to practice the medium in France, and Adolph Menzel in Germany. In 1862 the publisher Cadart tried to initiate a portfolio of lithographs by various artists, which was not successful but included several prints by Manet. The revival began during the 1870s, especially in France with artists such as Odilon Redon, Henri Fantin-Latour and Degas producing much of their work in this manner. The need for strictly limited editions to maintain the price had now been realized, and the medium became more accepted. In the 1890s, color lithography gained success in part by the emergence of Jules Chéret, known as the father of the modern poster, whose work went on to inspire a new generation of poster designers and painters, most notably Toulouse-Lautrec, and former student of Chéret, Georges de Feure. By 1900 the medium in both color and monotone was an accepted part of printmaking. During the 20th century, a group of artists, including Braque, Calder, Chagall, Dufy, Léger, Matisse, Miró, and Picasso, rediscovered the largely undeveloped artform of lithography thanks to the Mourlot Studios, also known as Atelier Mourlot, a Parisian printshop founded in 1852 by the Mourlot family. The Atelier Mourlot originally specialized in the printing of wallpaper; but it was transformed when the founder's grandson, Fernand Mourlot, invited a number of 20th-century artists to explore the complexities of fine art printing. Mourlot encouraged the painters to work directly on lithographic stones in order to create original artworks that could then be executed under the direction of master printers in small editions. The combination of modern artist and master printer resulted in lithographs that were used as posters to promote the artists' work. Grant Wood, George Bellows, Alphonse Mucha, Max Kahn, Pablo Picasso, Eleanor Coen, Jasper Johns, David Hockney, Susan Dorothea White, and Robert Rauschenberg are a few of the artists who have produced most of their prints in the medium. M. C. Escher is considered a master of lithography, and many of his prints were created using this process. More than other printmaking techniques, printmakers in lithography still largely depend on access to good printers, and the development of the medium has been greatly influenced by when and where these have been established. An American scene for lithography was founded by Robert Blackburn in New York City. As a special form of lithography, the serilith or seriolithograph process is sometimes used. Seriliths are mixed-media original prints created in a process in which an artist uses the lithograph and serigraph (screen printing). Fine art prints of this type are published by artists and publishers worldwide, and are widely accepted and collected. The separations for both processes are hand-drawn by the artist. The serilith technique is used primarily to create fine art limited print editions.