Recrystallization of Cerium Oxide in Porcelain Enamels

The effect of cerium oxide incorporated as the principal opacifying agent in the frit batch on the properties of white cover-coat porcelain enamels was studied. The effect of several variables on the opacity of the enamel was investigated as a function of firing temperature. Variables studied included (a) the amount of cerium oxide added, (b) the manner in which cerium oxide was incorporated into the enamel, i.e., mill addition, frit addition, or combination of both, (c) composition of the base glass, (d) weight of application, and (e) type of mill addition. Porcelain enamels were produced which had good acid resistance, high gloss, and a reflectance of 80% or more. Mill-added cerium oxide seemed to be less effective than that which was incorporated in the porcelain enamel as a component of the frit. The spectrophotometric analysis indicated good color stability of cerium oxide enamels.