F3110
Sodium borosilicate frit — high in soda, low in alumina · Fuses around 760°C · High thermal expansion — the crackle frit · Somewhat soluble in a standing glaze
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Frit 3110 is a sodium borosilicate frit, high in soda — a glass, melted and ground back to powder, which is how a flux that would dissolve in the glaze water is made to stay put. It raises thermal expansion a long way.
Frit 3110 is high in soda and low in alumina, and it raises thermal expansion a long way. As the main flux in a functional glaze it will craze, which is what makes it the crackle frit and what to add where a glaze is shivering. The low alumina also suits zinc crystalline glazes, and the high alkali suits copper turquoises. It fuses around 760°C — low enough that a glaze can seal over and trap bubbles before the body beneath has finished gassing. It is somewhat soluble, so a bucket left standing for months can precipitate.
