Abstract: A method for producing a glass-like protective layer on an optionally pre-coated metal or glass substrate. The method comprises: (a) mixing one or more defined silicon compounds with NaOH and KOH, (b) adding water to the mixture obtained in (a) to hydrolyze the silicon compound(s), (c) adding at least one defined compound of formula MYm, where M is Pb, Ti, Zr, Al or B, to the hydrolyzed mixture obtained in (b), wherein the molar ratio M/Si is from 0.01/1 to 0.04/1, to obtain a coating sol, (d) applying the coating sol obtained in (c) to the substrate, and (e) thermal densification of the coating sol applied in d) at a temperature of from 300° C. to 500° C. to form the glass-like protective layer.

Abstract: Metallic substrates with a vitreous or glass-ceramic pigmented protective layer are obtainable by applying an alkali metal silicate-containing coating sol to the substrate or a surface thereof and thermally densifying the layer thus obtained, said alkali metal silicate-containing coating sol comprising an oxidic pigment of at least one element selected from the third and fourth main or subgroups of the Periodic Table of the chemical elements and the transition metals Fe, Co, Ni, Cu, Zn, Nb and Ta.

Abstract: Metallic substrates with a vitreous or glass-ceramic pigmented protective layer are obtainable by applying an alkali metal silicate-containing coating sol to the substrate or a surface thereof and thermally densifying the layer thus obtained, said alkali metal silicate-containing coating sol comprising an oxidic pigment of at least one element selected from the third and fourth main or subgroups of the Periodic Table of the chemical elements and the transition metals Fe, Co, Ni, Cu, Zn, Nb and Ta.