Coloring effects of synthetic inorganic cobalt pigments in fast-fired porcelainized tiles

This paper reports a laboratory and industrial study on the rationalization of using synthetic cobalt oxide, aluminate, and silicate pigments (0.5-4.0 wt%) for coloring porcelainized stoneware tiles. Adding about 1-2 wt% of pigments to the base body does not appreciably modify the microstructure, nature, and amount of phases of the fired tiles, while higher amounts, by promoting liquid phase formation, favor the sintering and can cause swelling of compact samples.