Borax

About This Product

Borax, sodium tetraborate, is supplied as the decahydrate with CAS number 1303-96-4 or the pentahydrate, as white crystals or granules, moderately soluble in water and giving a mildly alkaline solution around pH 9.2. Two properties account for most of its use. It is an exceptionally stable buffer, holding pH near 9.2 across a wide dilution range, which is why borate buffer is a laboratory standard and why it appears in cleaning products and adhesives that must resist pH drift. And as a flux it dissolves metal oxides at high temperature, forming a low-melting glassy layer that both cleans the joint and protects it from air, which is the basis of its use in brazing, welding and in glass and ceramic manufacture, where it also lowers the melting point of the batch and reduces thermal expansion. It crosslinks polyvinyl alcohol and guar gum through borate ester bonds, which is used to build viscosity in adhesives and in oilfield fracturing fluids. Its EU classification as toxic for reproduction category 1B has removed it from most consumer products, though industrial use under controlled conditions continues. It is used in borosilicate glass and ceramic glazes, brazing and welding fluxes, buffers, adhesives, oilfield fluids and flame retardants. Bio Green Chem supplies borax to specification on B2O3 content, hydration state, chloride, sulfate, iron, insolubles and particle size, subject to permitted-use confirmation.