Production of printing blocks, resists, transparencies, prints and the like by electro-deposition

Claim 1

IN AN ETCHING METHOD WHEREIN A SUBSTRATE ADAPTED FOR BEING ATTACKED BY A PREDETERMINED ETCHANT IS COATED WITH A PHOTOCONDUCTIVE INSULATING LAYER WHICH IS SEQUENTIALLY ELECTROSTICALLY CHARGED AND EXPOSED TO A LIGHT IMAGE AND WHEREIN A DEVELOPER SUBSTANCE IN A LIQUID CARRIER OF HIGH ELLECTRICAL RRESISTIVITY IS APPLIED TO THE RESULTING ELECTROSTATIC IMAGE TO DEVELOP THE IMAGE WHEREIN SAID ETCHANT IS EMPLOYED TO ETCH THE THUSLY PROCESSED SUBSTRATE TO REMOVE PORTIONS OFF THE SUBSTRATE AND PHOTOCONDUCTIVE INSULATING LAYER WHICH ARE FREE OF DEVELOPER SUBSTANCE; THE IMPROVEMENT WHICH COMPRISES: PREPARING SAID PHOTOCONDUCTIVE INSULATING LAYER FROM A PHOTOCONDUCTOR AND BONDING RESIST AGENT, PREPARING SAID DEVELOPER SUBSTANCE FROM A PIGMENT AND BONDING RESIST AGENT, THE BONDING RESIST AGENTS BEING OF THE SAME MATERIAL, THE RATIO OF PHOTOCONDUCTOR TO BONDING RESIST AGENT BEING GREATER THAN THE RATIO OF SAID PIGMENT TO BONDING RESIST AGENT, THE AMOUNT OF BONDING RESIST AGENT IN THE DEVELOPER SUBSTANCE BEING SUFFICIENT TO WITTHSTAND ATTACK BY SAID ETCHANT, THE AMOUNT OF BONDING RESIST AGENT IN THE PHOTOCONDUCTIVE INSULATING LAYER BEING LESS THAN THE AMOUNT NECESSARY TO WITHSTAND ATTACK BY SAID ETCHANT.