What is Borax Decahydrate

Borax decahydrate or disodium tetraborate decahydrate is one of the most common sodium borate ores with chemical formula Na2B4O7.10H2O. The physical properties of borax decahydrate is a white monoclinic crystal that is soluble in water. In nature, it occurs as borax mineral from evaporation of deposits produced by the repeated evaporation of seasonal lakes.

Reactions with acids and bases will produce borates and dehydration will produce pentahydrate Na2B4O7.5H2O and other lower hydrates. Borax decahydrate will decompos at 75 degree celcius.

Manufacturing Process

Borax is obtained from lake brines, tincal, and colemanite. There are also primary salt constituent of brine such as sodium chloride, sodium sulfte, sodium carbonate, and potassium chloride. The percentage of borax as Na2B4O7 in brine is approximately 1.5 to 1.6 %. To separate borax from these salts, the brine solution is subject to evaporation and crystallization to remove NaCl, Na2CO3, and Na2SO4. The hot liquor consists of concentrated solution of potassium salts and borate. The insoluble solid particles are filtered and the hot liquor is cooled in continuous vacuum crystallizers under controlled conditions of temperatures and concentration to crystallize KCl. KCl is separated from the liquor by filtration and bicarbonate is added to the liquor to prevent the formation of sodium metaborate. Lastly, the liquor is evaporated and refrigerated to crytallize borax decahydrate.

The Uses of Borax Decahydrate

Detergent Industry
Borax is most known for its use in detergent industry as borax helps with the removal of oily soils from fabrics, imparts alkalinity, pH buffering, and softening of the wash water.
Cosmetics & Toiletries
Borax decahydrate is used as a cross linking agent to emulsify waxes and other paraffin as the base of lotions, creams, and ointments
Pharmaceutical Industry
Borax is the source of borate that is a suitable polymer bed used in medicine to diagnose hyperglycemia in diabete mellitus.
Cleaning Industry
As stated earlier, broax is also commonly used for cleaning agent. In industrial institutional borax is used for cleaning compund and it can also clean hard surfaces such as metals, glass, ceramics.
Paper Industry
Borax decahydrate is also used for starch adhesive formulation for corrugated paper and paperboard.
Other Applications
Borax decahydrate is also used for polishing and waxes, and it can also be used as a car antifreeze formulations as it is highly soluble in ethylene glycol.
Hazards Identification

Hazard Warnings: Borax decahydrate may be harmful if swallowed and can cause serious eye iritation. It also suspected of damaging the unborn child.

Precautionary Statements: Obtain special Instructions before use If exposed or concerned, get medical advice/attention Do not handle until all safety precautions have been read and understood. Wear protective gloves, eye protection. Dispose of contents/container to comply with local, state and federal regulations.


IUPAC NameSodium tetraborate decahydrate
CAS No1303-96-4
Molecular Weight381.37 g/mol
H.S. Code2840.19.00
SynonymBorax decahydrate, Sodium borate decahydrate


AppearanceWhite solid, granular/powder
ph @20°C9.3 (0.1% solution), 9.2 (1.0% solution), 9.3 (4.7% solution
Melting Point741°C
Boiling Point1575°C
Flash pointNon flammable
Vapour PressureNegligible @20°C
Relative Density1.72 @20°C
Solubility in Water4.7% @20°C; 65.5% @100°C