A lithographic printing plate structure and method of manufacture, in which a support sheet of steel, normally subject to corrosion in a lithographic environment, such as a mild steel, is coated, preferably on both sides, with aluminum, zinc or an aluminum-zinc alloy to a thickness of about 1 to 3 mils, a polyvinyl phosphonic acid is disposed on the metal coating and a negative working diazo photo- sensitive layer is applied over the polyvinyl phosphonic acid coating.
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