Effective factors on synthesis of the hematite–silica red inclusion pigment

The work focuses on the synthesis of a red ceramic pigment by inclusion of hematite in a fumed silica matrix with different specific surface areas. Iron(II) sulfate was used as hematite precursor. Mixtures of iron(II) sulfate and fumed silica with different mole ratios were heated at different temperatures from 1000 to 1300 °C for 4 h. Continuous changes in color were measured by comparing L*–a*–b* values of the heated samples. The fired pigments were enameled with a fritted glaze adding a 10 wt% of color in the glaze. The best red shades in the used glaze were obtained from samples heated at 1100–1200 °C for 4 h. Due to its chemical and thermal stability, the hematite/silica pigment may be considered as a suitable red pigment for ceramic manufacturing by fast firing cycles.