Stability of (Cr)CaO.SnO 2 .SiO 2 pink pigment in ceramic frits

Incorporation of the (Cr) CaO.SnO₂.SiO₂ pigment in ceramic glazes yields colours with a red component the hue of which depends on the nature of the frits used to produce the glazes. Several samples were prepared by adding this pigment to different frits commonly used in the manufacture of glazed ceramic tiles, each sample subsequently being fired at the appropriate maturing temperature. A study of the resulting glazes shows that variations in colour arise as a result of the three possible phenomena which may develop in firing depending on the frit composition used. These three phenomena are pigment dissolution in the glassy phase, devitrification of crystalline phases whose nature differs from that of the pigment, and immiscible glassy phase separation.