Metal Lithographic Plates Prepared by Xerography.

At the TAGA meeting in Rochester, New York, in April 1950, the use of xerography for preparing offset-duplicating paper plates was described. Such plates can be made in a few minutes using only a dry powder and simple procedures. This method is receiving widespread commercial acceptance. It now can be reported that, in the laboratory, metal lithographic plates can be prepared by xerography which produce results that are considerably superior to the results obtained from paper plates prepared by xerography. In fact, such plates appear good enough for use in printing military topographic maps. At present, the process is suitably only for reproducing line subjects, and additional work will be required before they can be used for halftone reproduction. In this process, an electrostatic image is created on a selenium-coated plate by exposure to a light image. This electrostatic image is developed with a dry powder, and the powder image is transferred electrostatically and fixed to a grained zinc plate. The entire operation can be completed in about five minutes. Plates as large as 27 by 30 inches have been made and larger sizes should present no insurmountable difficulties.