Method of stain-decorating glass-ceramics

Claim 1

A method for producing uniformly colored, neutral gray stain decorations in glass-ceramic articles which include inhomogeneities which affect stain coloration, comprising the steps of: forming a glassy article from a crystallizable glass composition comprising SiO 2 , Al 2 O 3 , Li 2 O, ZnO, and as a crystal growth nucleating agent, either TiO 2 or a mixture of TiO 2 and ZrO 2 ; heating said glassy article to a temperature at which a major portion of the article crystallizes within a glassy matrix, thereby forming a glass-ceramic; heating a quantity of palladium-containing stain-decorating composition separately from the glass-ceramic article to a temperature at which the stain-decorating composition is converted to a palladium-containing residue characterized by an ability to produce neutral gray stains when applied to previously crystallized glass-ceramic articles; mixing said palladium-containing residue with a liquid vehicle and applying the mixture to the surface of the glass-ceramic article; and heating the crystallized glass-ceramic article with the decorating mixture thereon to a temperature sufficient to migrate palladium ions from the mixture into surface portions of the article, thereby producing a uniformly colored, neutral gray stained pattern on the article.

Claim 2

A method for producing uniformly colored, neutral gray stain decorations in glass-ceramic articles which include inhomogeneities which affect stain coloration, comprising the steps of: forming a glassy article from a crystallizable glass composition comprising SiO 2 , Al 2 O 3 , Li 2 O, ZnO, and as a crystal growth nucleating agent, either TiO 2 or a mixture of TiO 2 and ZrO 2 ; heating said glassy article to a temperature at which a major portion of the article crystallizes within a glassy matrix, thereby forming a glass-ceramic; heating a quantity of palladium-containing stain-decorating composition separately from the glass-ceramic article to a temperature at which the stain-decorating composition is converted to a palladium-containing residue characterized by an ability to produce neutral gray stains when applied to previously crystallized glass-ceramic articles; mixing said palladium-containing residue with a liquid vehicle and applying the mixture to the surface of the glass-ceramic article; and heating the crystallized glass-ceramic article with the decorating mixture thereon to a temperature sufficient to migrate palladium ions from the mixture into surface portions of the article, thereby producing a uniformly colored, neutral gray stained pattern on the article.