The glazes serie „Gm“ are white and coloured frit, semi-raw and raw mat zinc glazes with the content of PbO 20-50% of the mass. With regard to considerably high content of lead and low chemical resistance, they are not recommended for the using to make the kitchenware.
In the art quarters, they are greatly popular for theirs noble silky mat surface with high reliability. In contradistinction to calficic mat glazes, they keep the mat in broad temperature interval 940-1100°C. At the temperatures over 1040°C, they flow down hard – above all the glazes Gm 805 91, Gm 852 91 and Gm 867 91.
The mat surface of this glazes is caused by crystallic phase of zinc silicate (willemit), that rises by the cooling of melted glaze.
They are suitable for white and in colour burny body with high thermal expansivity coefficient a > 75.10-7 K-1, On short body mass with a < 65.10-7 K-1 crackle hard as a rule.
They are engrained by colour metallic oxides and by ceramic pigments. The glazes Gm 057 91 and Gm 116 91 are not opaque wholly and they are influenced by the color of the mass.
They are suitable for all glazing techniques.
Recommended firing temperatures: 940 – 1 000 °C (1 100 °C).