Thermodynamic works of adhesion between a porcelain enamel and gold, platinum, palladium, graphite, and a gold‐base metal alloy were determined from surface‐tension and contact‐angle measurements. Theoretical shear strengths in the order of 80,000 psi were calculated from these data. Mechanical strength tests indicated values, however, of only 3000 to 10,000 psi for these interfaces. Wetting forces were therefore strong enough to account for the observed interface strengths. The strengthening effect of metal oxides on the bond strength is discussed in terms of the polarization and dislocation the