Self-Portrait (Passport Photographs, one with Altered Nose), 1956.
From autumn 1962 Warhol’s paintings were made almost exclusively by screenprinting photographic images on to backgrounds painted either in a single colour or in flat interlocking areas that corresponded approximately to the contours of the superimposed images. In these works, executed with the help of assistants in the studio that he called The Factory, he succeeded in removing his hand even more decisively from the canvas and in challenging the concept of the unique art work by repeating the same mechanically produced image until it appeared to be drained of all meaning. Among the most successful of these were portraits of glamorous film stars such as the recently deceased Marilyn Monroe, whose masklike face acquires an iconic quality in works such as Marilyn Diptych (for illustration see Pop Art), and gruesome images of car crashes and other daily disasters as seen in photographs reproduced in mass-circulation newspapers, such as Green Disaster Ten Times (1963; Frankfurt am Main, Mus. Mod. Kst). (moma.org)
Printmaking, and in particular screenprint, was the basic medium for Andy Warhol's celebrated work on canvas and paper. While a prize-winning commercial artist in the 1950s, he devised a printing process of blotting outline drawings in ink from one surface to another.