Cerdec Aktiengesellschaft Keramische Farben

Jenny Wilfert

Hans-Peter Letschert

Purple pigments according to the invention based on a stovable support material, in particular a glass frit, having a coat applied by coprecipitation of an oxide hydrate of one or more elements from the range comprising Al, Si, Sn, Pb, Ti, Nb, Ta, Sc, Y, La, Ce and Zn and a water-insoluble gold compound or colloidal gold are distinguished from prior art pigments of a similar composition by improved color stability in high temperature firing. The pigments are obtainable in the aqueous phase by coprecipitation of an oxide hydrate and a gold compound or colloidal gold in the presence of a support material and in the absence of a reducing agent. Pigments containing gold compounds assume a purple color on heat treatment or by chemical reduction. Preferred pigments containing gold compounds, which may directly be used as decorative colorants, conveniently develop their color during firing of the decoration.

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Hanau, Germany

Jenny Wilfert