Preparing planographic plates and solution therefor

Claim 1

A PROCESS FOR PREPARING A PLANOGRAPHIC PRINTING PLATE FROM A XEROGRAPHIC PLATE, SAID XEROGRAPHIC PLATE COMPRISING A RELATIVELY ELECTRICALLY CONDUCTIVE BACKING SHEET COATED ON AT LEAST ONE SIDE WITH A PHOTOCONDUCTIVE INSULATING MATERIAL COMPRISING AN ELECTRICALLY INSULATING RESIN BINDER HAVING SUSPENDED THEREIN A FINELY DIVIDED PHOTOCONDUCTIVE PIGMENT SELECTED FROM THE GROUP CONSISTING OF PHOTOCONDUCTIVE INSULATING METAL OXIDES AND METAL SULFIDES, SAID PROCESS COMPRISING PRODUCING AN ELECTROSTATIC LATENT IMAGE ON SAID PHOTOCONDUCTIVE MATERIAL, DEVELOPING SAID ELECTROSTACTIC IMAGE WITH A HYDROPHOBIC DEVELOPER POWDER, FIXING SAID POWDER IMAGE TO SAID MATERIAL, AND THEN TREATING THE POWDER IMAGE TO SAID MATERIAL, WITH AN AQUEOUS SOLUTION OF AN ACID THAT REACTS WITH SAID PIGMENT TO FORM CATIONS OF THE METAL THEREOF AND SAID SOLUTION ALOS CONTAINING ANIONS FORMING A HYDROPHILIC COMPOUND WITH THE METAL CATIONS RELEASED FROM THE PIGMENT BY THE ACID, SAID HYDROPHILIC COMPOUND BEING INSOLUBLE IN SAID AQUEOUS SOLUTION.