Method of manufacturing electrical apparatus

Claim 1

IN METHOD OF FORMING A CATHODE RAY TUBE SCREEN STRUCTURE INVOLVING THE STEPS OF DESPOSITING A FIRST LAYER OF UNEXPOSED PHOTOSENSTIVE MATERIAL ON A SUBSTRATE, EXPOSITING SELECTED REGIONS OF SAID TO ILLUMINATION, DEPOSITION A FIRST PHOSPHOR OVER A PORTION OF SAID LAYER INCULDING SAID EXPOSED REGIONS, REMOVING FROM SAID SUBSTRATE THE UNEXPOSED REGIONS OF SAID LAYER AND PHOSPHOR DEPOSITED THEREON WHILE LEAVING IN PLACE SAID EXPOSED REGIONS AND PHOSPHOR DEPOSITED THEREON, DEPOSITION A SECOND LAYER OF UNEXPOSED PHOTOSENSTIVE MATERIAL OVER SAID EXPOSED REGIONS AND ALSO OVER AREAS OF SAID SUBSTRATE FRON WHICH SAID UNEPOSED REGIONS HAVE BEEN REMOVED, AND DEPOSITING A SECOND PHOSPHOR OVER SAID SECOND LAYER, THE IMPROVEMENT WHCIH CONSISTS IN APPLYING TO SAID EXPOSED REGIONS OF SAID FIRST LAYER PRIOR TO SAID DEPOSITION OF SAID SECOND LAYER A WEAK AQUEOUS SOLUTION OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF POTASSIUM SILICATE AND LITHIUM HYDROXIDE, THEREBY TO PREVENT SAID SECOND PHOSPHOR FROM ADHERING TO SAID EXPOSED REGIONS OF SAID FIRST LAYER.