Lithium Carbonate

Lithium carbonate begins to flux at around 800°C and is active at every temperature above that. It is strong enough that a glaze usually contains only a few parts in a hundred, with reactive glazes using more. It brightens colour the way the alkalis do, and of the alkalis it is the one that adds least to a glaze's thermal expansion. About three fifths of its weight leaves as carbon dioxide during the firing, which is a lot of gas to pass through a melt. It also dissolves in water a little, which is unusual for a raw glaze material, so some of it travels with the water as a glaze dries and can concentrate at the surface.