Process for making a stencil screen coating and composition therefor

Claim 1

IN THE METHOD OF FORMING A PRESELECTED PATTERN OF VOIDS ON A STENCIL SCREEN COMPRISING THE STEPS OF FILLING THE VOIDS OF SAID STENCIL SCREEN WITH A COATING OF AN AQUEOUS MIXTURE OF GELATIN AND A LIGHT SENSITIZING AGENT, DRYING SAID COATING ON SAID SCREEN, PLACING AN IMAGE CONTAINING MEMBER HAVING TRANSPARENT AND NON-TRANSPARENT PORTIONS BEFORE SAID SCREEN, EXPOSING SAID SCREEN TO A LIGHT PASSING THROUGH SAID TRANSPARENT PORTION OF SAID IMAGE CONTAINING MEMBER, THAT PORTION OF THE GELATIN COATING IN SAID VOIDS OF SAID SCREEN CONTACTED BY SAID LIGHT BEING RENDERED WATER INSOLUBLE, THE REMAINDER OF SAID GELATIN COATING ON SAID SCREEN REMAINING WATER SOLUBLE, AND WASHING SAID SCREEN TO REMOVE SAID WATER SOLUBLE PORTION OF SAID GELATING COATING, SAID VOIDS CONTAINING SAID WATER INSOLUBLE COATING THUS DEFINING A PATTERN OF THE CONFIGURATION OF THE TRANSPARENT PORTION OF SAID IMAGE CONTAINING MEMBER, THE IMPROVEMENT WHEREBY SAID AQUEOUS MIXTURE OF GELATIN AND A LIGHT SENSITIZING AGENT CONTAINS A MEMBER SELECTED FROM THE GROUP CONSISTING OF ALKYL ESTERS OF MALONIC, SUCCINIC, GLUTARIC, ADIPIC, PIMELIC, SUBERIC, AZELAIC, SEBACIC, OLEIC, LINOLEIC, LINOLENIC, AND ELEOSTEARIC ACIDS, SAID ALKYL CONTAINING FROM 2 TO 10 CARBON ATOMS, AND THE AMOUNT OF GELATIN BEING FROM 33 TO 80 PARTS BY WEIGHT BASED ON THE COMBINED WEIGHT OF GELATIN AND ALKYL ESTER.