Plainsman Clays | GIBO
Gillespie Borate
Gillespie Borate is a proportioned blend of borate minerals, mainly ulexite with a little colemanite. It supplies boron, which begins to melt well below the other common glaze fluxes, so it is used in low and mid range recipes.
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Gillespie Borate is blended to a set chemistry, and none of it has been fused into glass. Part of the boron is therefore soluble in water, and the dissolved part moves as a glaze dries, giving the broken, mottled surfaces this material is known for. The blend includes a small amount of fine clay like matter, enough to make a slip workable, though a glaze left standing for a long time needs an added clay to stay suspended. Raku and crackle recipes often use it as the main flux, and at mid range it is usually one ingredient among several.
- A proportioned blend of borate minerals, mainly ulexite
- Supplies boron, which melts well below the other common fluxes
- Not a frit, so part of the boron dissolves in water
- Used heavily in raku and crackle recipes
