Method of producing indicia-bearing surfaces

Claim 1

A PROCESS OF PREPARING AN INDICIA-BEARING METAL SURFACE SELECTED FROM THE GROUP CONSISITING OF MAGNESIUM, MAGNESIUM ALLOYS, ALUMINUM, ALUMINUM ALLOYS AND STAINLESS STEEL, WHICH COMPRISES COATING A CLEAN METAL SURFACE WITH A LAYER OF A CONTRASTING COLORED PIGMENTED LACQUER SUBJECT TO DISINTEGRATION AND REMOVAL BY A HOT CHROMIC ACID BATH, DRYING THE LACQUER LAYER, CLEANING THE LACQUER LAYER WITH A VOLATILE ORGANIC LIQUID WHICH DOES NOT ATTACK THE LACQUER SURFACE, COATING THE LACQUER LAYER WITH A PHOTOSENSITIVE LAYER, EXPOSING PORITIONS OF THE PHOTOSENSITIVE LAYER, DEVELOPING THE PHOTOSENSITIVE LAYER TO REMOVE THE UNEXPOSED PORTIONS THEREOF TO PROVIDE BOTH RESISTANT AND UNPROTECTED AREAS OVERLYING THE LACQUER LAYER, BAKING TO HARDEN THE RESIST LAYER; SUBJECTING THE LACQUER AND RESIST TO A HOT AQUEOUS SOLUTION OF CHROMIC ACID UNTIL THE PIGMENTED LACQUER LAYER NOT COVERED BY THE REIST IS DISINTEGRATED AND REMOVED, RINSING IN WATER, BRIGHTENING THE UNPROTECTED METAL AREAS BY TREATMENT WITH DILUTE WATER SOLUTION OF NITRIC OR HYDROCHLORC ACID, RINSING IN WATER, REMOVING THE EXPOSED, HARDENED AREA OF RESIST BY MEANS OF A SOLVENT FOR THE RESIT, WASHING THE METAL AND COATING THE DRIED LACQUER SURFACE WITH A COAT OF A CLEAR PROTECTIVE LACQUER.