Method for making stained glass photomasks from photographic emulsion

A method of making a stained glass photomask comprising:

• providing a flat glass substrate with a layer of photographic emulsion containing silver halide on a first surface of the glass substrate;
• placing a master mask over the photographic emulsion layer and exposing patterned areas of the photographic emulsion to actinic radiation through the master mask;
• contacting the exposed photographic emulsion with photographic developing solutions, thereby producing on the first surface of the flat glass substrate a pattern of electroconductive silver-containing emulsion areas and silver-free areas;
• applying a first electrode layer onto the developed photographic emulsion on the first side of the glass substrate and applying a second electrode layer onto the glass surface on the opposite side of the glass substrate from said first surface;
• connecting said first electrode layer to the anode side of a source of electrical potential, connecting said second electrode layer to the cathode side of the source of electrical potential, and simultaneously heating the glass and the layers carried thereon to a temperature between about 100.degree. C. to 350.degree. C. while applying a direct current electric field between the electrode layers so that electric charge passes through the silver-containing emulsion areas and the thickness of the glass substrate and induces migration of silver ions from the silver-containing emulsion areas into portions of the glass underlying the silver-containing emulsion areas while portions of the glass substrate underlying the silver-free areas remain essentially free from migrated silver ions;
• maintaining the glass at an elevated temperature in the presence of a reducing agent for a sufficient time to reduce and agglomerate the migrated silver ions within the glass, thereby producing a stained pattern within the surface of the glass.