GOUGE RESISTANCE OF PORCELAIN ENAMELS*

An exploratory study was made to determine possibilities of the Porcelain Enamel Institute rolling-ball gouge test as well as to discover some of the factors influencing the gouge resistance of enamels as shown by the test. The test results compare favorably with deep-scratch and gouge defects encountered in actual enamel practice. The accuracy of test results, moreover, compares favorably with other such physical tests designed for use with porcelain enamel. The gouge resistance is shown to be a function of enamel thickness and of bubble structure. Factors which increase or decrease bubble structure, such as mill additions, frit compositions, and firing treatment, are shown to affect gouge resistance.