PUBLIC MARKS with tags printing & Xerox

On October 22, 1938, when American inventor Chester Carlson together with German immigrant Otto Kornei first transferred an image from a glass microscope slide to a sheet of wax paper using method later called electrophotography. Kornei wrote the words “10.-22.-38 ASTORIA.” in ink on a glass microscope slide. Then the experimentalists prepared a zinc plate with a sulphur coating, darkened the room, rubbed the sulphur surface with a handkerchief to apply an electrostatic charge. After that they laid the slide on the zinc plate, exposing it to a bright, incandescent light.

This new method is side product of Xerox’s larger studies to put more security into digitally printed documents by making any element on the page - such as lines, text, and images - unique to the recipient.