A New Chromium Long-life Lithographic Plate.

An application of the deep etch process to the preparation of a chromium Iithographic plate is discussed. Descriptions are given of the type of plate used and of the chemicals utilized in the various steps of plate preparation. The plate is made by electrodepositing a relatively thick layer of chromium on a suitably grained zinc plate. With the exception of the etch which dissolves the chromium, all the chemicals required are those normally employed in preparing deep etch plates on zinc by the gum process. The chromium etch, though of essentially usual composition, contains a metal catalyst which readily activates chromium to permit controlled rates of reaction relatively unaffected by temperature changes.