Opaque and Coloured Glasses and Ceramic Glazes of the same Nature

JSGT 1923 V07 T291-T295

When seeking an explanation of the phenomena occurring during the opalisation of glasses, one is led to suppose that at a certain stage an insoluble body is produced, which remains in suspension in the vitreous liquid. On pushing the reaction further, one may finally obtain a glass which is completely opaque. Among the opacifying agents, the fluorides, fluorspar, and cryolite play an important part. With a certain charge, predetermined for a given glass, one may obtain an opaque glass on first pouring, but with a smaller quantity the same opacification is only obtained on reheating the glass.

Albert Granger