Method for making aluminum alloy lithographic plates or Al/Ca lithographic alloy
AssigneeThe British Aluminum Company Limited
InventorAlan Gray
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Abstract
A method of making a lithographic plate by etching in an alkaline bath a sheet of an alloy of aluminium and 0.1% to 4.5% calcium. The alloy preferably contains up to 2.0% magnesium.
Claims10
A method of making a lithographic plate from an aluminium base alloy containing 0.1% to 4.5% Ca together with normal impurities comprising subjecting at least one side of the plate to an alkaline etching process in a solution selected from sodium hydroxide and a solution produced by dissolving in water the hydroxides of alkaline metals or ammonia until a dense substantially uniform distribution of pits having an average depth ranging between 0.2 .mu.m and 3.0 .mu.m is formed on said one side.
Dependencies are inferred from the claim text.