Sodium Tetraborate (Borax)

Sodium tetraborate has several pseudonyms including Sodium Borate, Disodium Tetraborate, Disodium Salt, Boric Acid, Sodium Borate Decahydrate and more commonly known Borax. Derived as a hydrate salt of Boric Acid, it occurs naturally as seasoned lakes repeatedly cycle and evaporate, leaving behind a build-up of powdery crystal deposit which is the salt of Boric Acid. Borax is essentially a combination of Sodium, Boron and Oxygen.

The white granular powder is water soluble and has several applications from household cleaners to pesticides, enamel manufacturing to the artificial aging of wood, a buffering agent in chemistry to an alkalizer in the pharmaceutical industry. In recent years it has become popular as the ‘activator’ in play putty or Hand Slime.

Borax is safe to use but we advise caution and to always keep out the reach of children.

Physical Analysis

Chemical Formula: B4O7Na2·10H2O, Na2B4O7·10H2O, B4H20Na2O17

Molar Mass: 381.37 (decahydrate)

Appearance: white, crystalline solid

Density: 1.73 g/cm3 (decahydrate, solid)

Melting Point: 743 °C (1,369 °F; 1,016 K)

Boiling Point: 1,575 °C (2,867 °F; 1,848 K)

Solubility in water: 31.7g/L

pH: Alkaline

E Number: E285 (preservatives)

CAS Number: 1303-96-4

Material Safety Data Sheets for all products are available here.