Composite developer-etch composition for chromium-plated lithographic printing plates
AssigneePrinting Developments, Inc.
InventorsVincent A. Pagliaro, Richard G. Walters
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Abstract
A composite developer-etch composition for chromium-plated lithographic printing plates comprises an aqueous solution of aluminum chloride, a water-soluble chloride other than aluminum chloride, phosphoric acid, and an acid-stable water-soluble reducing agent; the composition having a particular specific gravity range.
Claims6
A single step process for both developing and etching a chromium-plated lithographic printing plate having a light exposed photosensitive resist gum coating thereon which comprises treating said plate with a composite developer-etch composition comprising an aqueous solution of from about 16% to about 22% by weight of aluminum chloride, from about 20% to about 26% by weight of a water-soluble chloride other than aluminum chloride, from about 2.2% to about 4.0% by weight of 85% strength phosphoric acid, from about 0.6% to about 1.4% by weight of an acid-stable water-soluble alkali metal or alkali earth metal hypophosphite reducing agent and the balance water;
- said composition having a specific gravity at 70.degree. F. of from about 1.4 to about 1.5.
Dependencies are inferred from the claim text.