Borosilicate

A silicate is an SiO₂-centric solid (crystalline or glass). A borosilicate simply is a silicate with boron. In ceramics, the term 'borosilicate' is synonymous with medium and low fire glazes. Boron is seldom employed at high temperatures because other much more convenient and less expensive fluxes like CaO, KNaO, MgO bond well with silica to form crystalline or glass solids. The term 'borosilicate' almost always refers to a frit in ceramics. Such frits may have 5% B₂O₃ or 50%, but they always have plenty of SiO₂ (plus other oxides). Since boron is the melter that makes the glaze or glass possible, terminology referring to the chemistry normally mentions it.

Borosilicate glass, not ceramic, is typically 70–80% SiO₂, 7–13% B₂O₃, 4–6.5% Na₂O or K₂O, and 2–6% Al₂O₃.

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Glossary	High Temperature Glaze
Glossary	Medium Temperature These are stoneware glazes that fire in the range of 1200C (2200F). They often contain boron to assist with melting.
Glossary	Borate Borate glazes, those fluxed with the oxide B2O3, are the most common type used in ceramic industry and hobby for low and medium temperatures.
Glossary	Frit Frits are used in ceramic glazes for a wide range of reasons. They are man-made glass powders of controlled chemistry with many advantages over raw materials.
URLs	http://en.wikipedia.org/wiki/Silicate Silicate at Wikipedia

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