Abstract: The invention relates to lead- and cadmium-free glass for glazing, enamelling and decorating glasses or glass-ceramics which have a low coefficient of thermal expansion of less than 2×10−6/K, having the composition (in % by weight) 0-6 Li2O, 0-5 Na2O, 0 to less than 2 K2O, where the sum Li2O+K2+Na2O is between 2 and 12, 0-4 MgO, 0-4 CaO, 0-4 SrO, 0-1 BaO, 0-4 ZnO, 3 to less than 10 Al2O3, 13-23 B2O3, 50-65 SiO2, 0-4 TiO2, 0-4 ZrO2 and 0-4 F, as replacement for oxygen and containing up to 30% by weight of a pigment which is resistant at the firing temperature, where the glass is suitable for glazing, enamelling and decoration in both primary and secondary firing, and both the full-area and sparse glaze, enamel or decoration layers have low abrasion susceptibility after firing, and it relates to processes for the production of a glass-ceramic coated therewith.

Abstract: A method of making a porous refractory article and a dispersion of particles in a liquid carrier, the method involving forming a dispersion of particles in a liquid carrier, introducing gas into the dispersion, removing the liquid carrier to provide a solid article having pores derived from the bubbles and wherein the dispersion has a critical viscosity below the level at which the introduction of gas cannot take place and above the level which entrapped gas bubbles will tend to escape and with the dispersion having the same critical viscosity.