Plainsman Clays | FLOU
Fluorspar
Fluorspar is calcium fluoride, the mineral fluorite, ground to a powder. It is used as a source of calcium and as a strong flux where a more fusible melt is wanted, and above about 1000°C the fluorine in it leaves as gas.
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Fluorspar is used in a glaze as a source of calcium and as a strong flux. It melts at around 1418°C, well beyond any pottery kiln, so it never melts on its own. It works by dissolving into the glaze around it, where the fluoride breaks up the silicate network and brings the melting point down sharply. It replaces whiting in a glaze where a more fusible melt is wanted, and it is also used in frits and low fire enamels. Above about 1000°C the fluorine leaves as gas, which can cause blisters and pinholes in a glaze.
- Calcium fluoride, the mineral fluorite, ground to a powder
- A source of calcium and a strong flux where a more fusible glaze is wanted
- Used in frits and low fire enamels as well as glazes
- The fluorine leaves as gas above about 1000°C, which can blister a glaze
