Stained glass photomasks and method of making by electrodealkalization

A method for making a stained glass photomask comprising the steps of:

• applying a nonconductive masking film onto a surface of a glass substrate containing alkali metal ions;
• photographically producing a pattern of apertures through the masking film;
• imposing a direct current electric field across the glass substrate and the apertured masking film in a direction substantially normal to said surface of the glass substrate, with the masking film side as anode, and simultaneously heating the glass substrate to at least 100.degree. C., thereby migrating alkali metal ions out of surface portions of the glass directly underlying the apertures in the masking film toward the interior of the glass so as to yield a pattern of metal ion depleted areas at said surface of the glass substrate, while the masking film maintains the alkali metal ion content essentially unchanged in the remaining surface portions of the glass substrate lying directly thereunder;
• removing the masking film from said surface of the glass substrate;
• spreading onto said surface of the glass substrate a fluid staining composition including a source of stain-producing cations;
• subjecting the glass substrate carrying the staining composition to ion migrating conditions, thereby migrating stain-producing cations from the staining composition into said remaining surface portions of the glass substrate, and insubstantial migration of the stain-producing ions occurs in said alkali metal ion depleted surface portions;
• and
• heating the glass substrate in the presence of a reducing agent to reduce and agglomerate the migrated stain-producing cations within the glass, thereby rendering the stain-producing cation migrated surface portions of the glass substantially opaque to radiation of a given wave length while said alkali metal ion depleted surface portions remain substantially transparent to said radiation.