About Calcium Borate

Calcium borate is a boron bearing mineral supplied principally as colemanite (Ca₂B₆O₁₁·5H₂O), a hydrated calcium borate. It occurs as white to grey crystalline material, is mined and milled from sedimentary borate deposits in Turkey and the western United States, and has low solubility in water compared with refined borates such as borax and boric acid. That low solubility is an advantage where boron needs to be delivered slowly or held in a solid matrix. Calcium borate is supplied in a range of particle sizes and B₂O₃ contents, from coarse granular through to finely milled powder.

Calcium Borate Uses

Fibreglass and Insulation

Colemanite is the main boron source in textile fibreglass and glass wool insulation. It lowers the melting temperature of the batch, reduces viscosity for consistent fibre drawing, and improves the chemical durability and strength of the finished fibre.

Glass and Ceramics

The mineral acts as a flux in borosilicate glass, frits, enamels and ceramic glazes, cutting energy use by lowering firing temperature. It improves thermal shock resistance, surface gloss and the bond between glaze and body, while supplying calcium alongside boron.

Flame Retardants and Polymers

Calcium borate is used as a smoke suppressant and char forming flame retardant in PVC, rubber, cable compounds and coatings. Its low solubility means it stays in the polymer matrix rather than leaching out, giving durable performance in service.

Metallurgy and Agriculture

Steelmakers use colemanite as a slag conditioner and as a component of continuous casting mould powders, where it controls slag viscosity and heat transfer. In agriculture, its low solubility makes it a slow release boron source for granulated fertiliser blends.

Calcium Borate Supplier Australia, USA & More!

Redox are trusted, authorised suppliers of Calcium Borate. With distribution centres worldwide, we can supply to Australia, USA, UK, NZ, Europe, Asia and more. Get in touch with our expert team, who can help you order the right product, form and amount for your needs.