Lead free Cu-Containing Frit for Modern Metallic Glaze

A lead-free frit containing high amount of copper and its glazeconceived for fine porcelain stoneware tiles were investigated.The glazes obtained under industrial firing were studied using Xrayphotoelectron spectroscopy, X-ray diffraction, optical andscanning electron microscopy with energy dispersion spectroscopy.The mechanism of the red color formation on the surfacewas explained. The results indicated that the glaze presents ametallic gloss and iridescent colors on the surface, mainly associatedto the formation of CuO crystallites and Cu metallicparticles. Moreover, the Cu glaze showed a good chemical durability;this is particularly interesting because commercial Cufrits usually present poor chemical properties.