Method for providing a co- and ni-free vitreous enamelled metal coated steel substrate and a primer composition therefor

A method for producing a metal coated steel substrate provided with a coating of a primer composition, comprising applying a layer of the primer composition on the metal coated steel substrate, wherein the primer composition comprises:

• one or more basic components (B) selected from the group consisting of CuO, K2O, Li2O, Na2O, CeO2 and ZnO;
• one or more components with intermediate acidity (IN) selected from the group consisting of Al2O3, B2O3, Cr2O3, SnO2, Sb2O3 and Fe2O3;
• one or more acidic components (A) selected from the group consisting of MnO2, MoO3, P2O5, SiO2, TiO2, V2O5, WO3 and ZrO2;
• and
• wherein all wt. % are drawn on the total primer composition and the total sum of the amounts excluding impurities and after normalization is 100 wt. %,
• wherein all components are expressed as oxides, wherein the sum of the amounts of CeO2+Cr2O3+CuO+Fe2O3+MnO2+MoO3+SnO2+Sb2O3+V2O5+WO3 is between 16.7 and 48.6 wt. %, and wherein the sum of the amounts of CeO2+CuO+Fe2O3+MoO3+SnO2+WO3 is between 18.9 and 48.6 wt. %, and firing the metal coated substrate with the primer composition.