Polychrome Corporation

Donald J Riley

Jen-chi Huang

Jen-Chi Huang

Gregory Von Gruenberg

A method for producing aluminum sheets for lithographic plates by electrolytically etching the surface in an aqueous mineral acid electrolyte solution utilizing direct current with superimposed alternating current. The surface of aluminum plate sheets may be mechanically grained prior to the step of electrolytic etching.

Method of electrolytically graining aluminum metal sheets suitable for

A method is provided for electrolytically graining an aluminum lithographic plate to produce a grained surface with a honeycomb topography, non-directional grain structure, and a substantially reduced production of smut. The reduction of smut is achieved by utilizing an alternating current of higher frequencies, generally in the range of approximately 140 to 400 Hz.

Method of electrolytically graining a lithographic plate

The invention features an electrolytic process for producing lithographic plates. The plates are immersed in a bath and fed a shaped alternating wave having a multiplicity of zero voltage intermissions. The grain topography of the plate can be varied by changing the frequency and duration of the intermissions in the wave.

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Tenafly, NJ, United States of America

Donald J Riley