Color Stability of Clear and Opaque Titania Enamels Containing Various Color Oxides

Abstract

A study was made of the spectrophotometric characteristics of a clear and an opaque titaniabearing enamel. Three and six per cent additions of green, blue, brown, and red oxides were made to the base enamels. After firing the enameled samples over a range of time and temperature, spectrcphotometric and Xray data were obtained. The results indicate that the lack of stability of the opaque colored enamels is due to the change from a blue-white to a cream-white color on increased firing treatment. The addition of a cream component tends to shift the hue of the fired enamel toward the red end of the visible spectrum. The green and the blue colors were much less stable than the red. X-ray data show that the total anatase present decreases, which is evidence that a cream-white color developed. X-ray data did not indicate any change in crystal structure of the anatase, rutile, or color oxide. Titania present in the glass of the clear enamel did not cause color instability.

Development of TiO2 white glazes for ceramic tiles☆

“…Mill additions can directly influence porcelain glaze viscosity and oxidation/reduction conditions in the coating. Both these effects alter the fired coating [19,20]. The furnace atmosphere also alters the oxidation/reduction conditions and can alter glass viscosity through moisture variations.…”