The ceramic glaze and frit industry's boron mineral of choice. 1.8 g/L solubility. Does not pre-dissolve. Ever.

Ground colemanite (Ca₂B₆O₁₁·5H₂O) does not dissolve in glaze suspension water. That single physical property — water solubility of only 1.8 g/L at 20°C — makes it the standard boron source for ceramic frit and glaze production worldwide. Where boric acid would dissolve into the water phase and migrate non-uniformly during drying, colemanite remains as a mineral particle and releases its B₂O₃ only at frit furnace or kiln temperatures above 800°C. The result is a homogeneous, reproducible fired glaze — every batch, every tile, every firing cycle.