Stable color dispersions, their preparation and use in ceramic glazes

摘要

A colored ceramic glaze is prepared from a raw glaze containing glass frit, clay and one or more ceramic pigments added as an aqueous dispersion. The raw glaze is ball-milled after which it is blended with the aqueous dispersion. The dispersion contains up to 70% of a ceramic pigment, such as zirconium-vanadium yellow, preferably with 1% to 3% of a suspending agent, up to about 1.5% of a thickener, an effective amount, but no more than 1% of a dispersant, and a biocide as needed. The suspending agent preferably is attapulgite clay or a water- swellable smectite clay. The thickener is preferably a xanthan gum and the dispersant is typically an ammonium salt of a medium molecular weight polymethacrylic acid. A stronger, more intense color is achieved by adding the ceramic pigment as a dispersion as opposed to ball-milling it with the glass frit as has been the traditional approach.