Screenless lithography

Screenless lithography is a reprographic technique for halftoning dating to 1855, when the French chemist and civil engineer Alphonse Poitevin discovered the light–sensitive properties of bichromated gelatin and invented both the photolithography and collotype processes. After the invention of the halftone screen in the 1880s, screenless lithography was abandoned. Until the end of World War II, two kinds of photomechanically made plates were used in lithography: albumin plates and deep-etch plates. Presensitized plates appeared in the 1950s, and wipe–on plates appeared in the 1960s.