Abstract: Processing of lithographic printing plates, particularly a method of preventing bending of the plates during processing.Conventionally, the chemical processing of lithographic printing plates includes advancing the plates between pairs of rotating brushes. The trailing edge of such plates is bent upwardly or downwardly after passing through the pairs of brushes. The present method places the pairs of brushes at an oblique angle with respect to the axis of advancing such that the leading and trailing edges of the lithographic plate laterally incrementally contact the brushes. As a result, bending is eliminated.

Abstract: A metal base lithographic printing plate cleaned and treated by RF plasma to render the non-exposed area hydrophilic, then coated with either a negative working or positive working photosensitive coating. The method is characterized by its elimination of the conventional alkaline etch with attendant hazard, pollution and toxicity problems.

Abstract: This invention provides for improved printing inks which cure upon exposure to ultraviolet radiation and furthermore demonstrate greatly extended shelf lives and stability as compared to prior art inks. The photosensitive component of the ink comprises a mixture of Michler's ketone and an o-halogen substituted hexa-aryl biimidizolyl compound.

Abstract: A method for electrolytically graining the surface of aluminum sheets useful in the production in lithographic printing plates which comprises subjecting said aluminum sheets to the action of an electric current in an aqueous electrolytic solution containing, in combination, small but effective amounts of both hydrochloric and tartaric acids.

Abstract: A method of producing an aluminum base sheet for printing plates is shown. The improvement comprises three steps in sequence including electrolytically graining the surface of the aluminum sheet by exposing it to a chemical etching bath comprising a chloride containing electrolytic solution and impressing a current on the sheet; thereafter cathodically cleaning the grained sheet by exposing it to a concentrated solution of sulfuric acid and again impressing a current on the sheet; and finally anodizing the cathodically cleaned sheet by exposing it to a second concentrated solution of sulfuric acid and imposing a current on the sheet. In the preferred embodiment, the electrolytic graining is carried out in the presence of hydrochloric acid and in an alternating current; and the cathodic cleaning and anodizing steps are carried out in sulfuric acid and in a direct current. In the preferred embodiment of the invention a web of aluminum is continuously moved through three treating baths in series.