Patent ID: 7846858

Claim:
A glaze for annealing surfaces, comprising the following components by mass: 30 to 55% SiO 2 , 0 to 7% Al 2 O 3 , 10 to 30% R 2 O, 5 to 10% R′O, 0.5 to 15% B 2 O 3 , 5 to 10% Bi 2 O 3 , 1 to 10% P 2 O 5 , 0 to 5% Sb 2 O 3 , 0 to 5% SnO 2 , 0 to 5% TiO 2 and 5 to 10% ZrO 2 , wherein (R) is one or several alkali metals and (R′) is one or several bivalent metals from the group comprising alkaline earth metals and zinc, and wherein the glaze is obtained by melting or sintering the components.