The Guth Printing Plate.

The Guth printing plate comprises a support which has been coated with a dichromated gelatin. A relief is produced directly when the plate is exposed to light and heat through a halftone or a design. First, a tanned image is formed, and as the coating heats up, one can actually see the relief develop. Without further development, the exposed plate is ready for direct printing, for stereomat preparation, or for use as a mold for a cast metal relief printing plate. An investigation has been made of the limitations of this plate, of its potential field of application, spot news pictures, and of the mechanism by which the relief is formed.