Lithography is a type of surface printing. It is used both as an art and commercial printing process. In commercial printing, it is synonymous with offset printing. Lithography is based on chemical action between oil and water. Lithograph, on the other hand, implies a print on stone. However, in commercial printing, grained metal or plastic plates are used instead of stones.
The discovery of lithography was made possible by Aloys Senefelder, a playwright, when he used Bavarian limestone for and art piece. It was in 1880’s when lithography was widely used for magazine printing. However, it become popular in the 19th century when renowned artists like Bonnard, Degas, Delacroix, Daumier, Gavarni, Goya, Manet, Toulouse-Lautrec and Whistler used it for their posters and other works of art.
In the early days of colored lithographs, only one or two colors were used to tint the entire stone or plate. Moreover, the process has improved in the beginning of the 20th century to accommodate more colors and to make possible photolithography. In photolithography, a photo negative is exposed to light over a gelatin-covered paper. Those parts of the gelatin that were struck by light rendered them insoluble. Those which are not struck remained soluble. When the soluble parts are washed away, the pattern is formed. This pattern is inked and transferred to the stone or plate. If more colors are to be printed, more stones or plates are required. Thus, the number of stones or plates needed depends on the numbers of colors to be used. In todays wholesale printing services, photolithography plays a crucial role in reproducing modern artworks.
Transfer lithograph was consequently discovered. With this process, the drawing is made on paper and transferred by pressure to a heated stone. Transfer lithograph does not require the drawing to be placed upside down. This is why it is considered easier than the conventional lithography. After that, the surface of the stone that was not affected by oil is desensitized to the drawing. Then, the portions drawn upon are fixed against spreading. A gum arabic and nitric acid solution is used afterwards. The oil has now penetrated the stone. To see the image accurately, use turpentine and water to remove unwanted chemicals. Now, the stone is ready to be inked and printed but be sure to keep the stone moist. Printing will make use of a special lithographic press with a sliding bed passing under a scraper.
Among the printing processes available, lithography is one of the least limited. It can produce colors from solid black to gray and full range of colors. This is the primary reason why it is famous for magazine and brochure printing. It certainly captures the photographic quality and fine gradations of pictures at a wholesale price.