MANUFACTURE OF A PLANOGRAPHIC PRINTING PLATE

摘要

A method for the preparation of a planographic printing plate wherein a photoexposed and developed photographic material containing a pattern of poorly water-soluble silver salt is treated with an aqueous liquid which contains in dissolved state an organic cationic compound or mixture of organic cationic compounds, iodide ions, and a sufficient amount of hydronium ions (H3O+) for creating an acidic medium, said liquid being capable of making an unexposed and undeveloped photographic silver halide material as defined in the disclosure sufficiently receptive for a lithographic ink.