Lithography is a method for printing using a stone (lithographic limestone) or a metal plate with a completely smooth surface. Lithography originally used oil or fat. However, in modern times, the image is now made of polymer applied to anodized aluminium plates. The smooth surface is divided into (1) hydrophilic regions that accept a film or water and while damp these areas reject ink, and (2) hydrophobic (water repelling) regions which accept ink because the surface tension is higher on the greasier image area which remains dry because the water will part and run off the greasy image. This process is quite different to gravure or intaglio printing where a plate is engraved, etched or stippled to make cavities to contain the printing ink, and in woodblock printing and letterpress ink (non waterproof) is applied to the raised surfaces of letters or images.
Invented in 1796 by Bavarian author Alois Senefelder as a low-cost method of reproducing artwork, lithography 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.
Lithography: a modus utilized in offset printing. Offset printing principally covers the idea that the printing plate, printing and non printing surfaces exist. Contact between ink, water and the printing plate is the norm. Initially, use of oil and fat was common.