Method of coloring glass sheet by diffusion and reduction of silver ions

Abstract

A method of coloring a glass sheet which must contain reducing ions such as tin ions diffused into a surface layer thereof. The reducing ions may originate in a molten metal bath used in producing the glass sheet by the float process. A coloring agent comprising a powder mixture of 1 part by weight of a substance expressed by Ag.sub.x W.sub.y O.sub.z, wherein x:y:z is 1-2:1:2-4, and 5 to 20 parts by weight of a transition metal oxide, e.g. Cr.sub.2 O.sub.3, is applied to the glass sheet surface, and the glass sheet is heated so as to cause silver ions to diffuse into the surface layer of the glass sheet and undergo reduction by the action of the precedingly diffused ions to produce color. Conveniently, use is made of a paste prepared by dispersing the powder mixture in an organic liquid vehicle. Owing to the stability of the silver-containing oxide Ag.sub.x W.sub.y O.sub.z, uniform coloring is achieved without encountering difficulty and without degrading the quality of the glass sheet.

Dependencies are inferred from the claim text.