AUF GLAS- ODER GLASKERAMIKSUBSTRATE AUFGEBRACHTE DEKORSCHICHTEN AUS KERAMISCHEN FARBEN

2.1 Hitherto, differences between the coefficients of thermal expansion of glass-ceramic substrates and decorative layers made from, in particular, lead-free base enamel meant that only very thin, relatively rough colour layers with restricted service properties could be baked on the substrate. The object is to provide a process for the production of substrates coated, in particular, with lead-free ceramic colours are made from preshaped borosilicate glass or glass-ceramic elements, allowing an intensely coloured, firmly adherent decorative layer having the thickness necessary for continuous coating to be obtained. 2.2 Before the baking together with the pigments, heat-resistant, optically inactive, elastic, inorganic substances in finely divided form which are chemically inert towards the base enamel and the pigments are admixed with the base enamel in an amount of 1-20% by weight. The load limit of the resultant decorative layer is thus not achieved until a larger layer thickness. 2.3 In this way, decorative layers of, in particular, lead-free base enamel can be applied in a firmly adherent manner to substrates having a low coefficient of thermal expansion.