Borax Pentahydrate - Overview

Borax pentahydrate, also known as Etibor 48 or sodium tetraborate pentahydrate, is the most common form of sodium borate used in various industries. It is a white, odorless crystalline granular or powder product that is mildly alkaline both alone and in solution. Compared to Borax Decahyrdate, which is physio-chemically comparable, Etibor 48 has a higher Boron content per unit mass, a lower ratio of bound water and is less hygroscopic. The physical preperties of borax pentahydrate is soft colorless hexagonal crystal and it is soluble in water and alcohols (17% in methanol and 31% in ethylene glycol by weight). In nature, borax pentahydrate occurs as mineral tincalconite, formed by dehydration of borax. Borax pentahydrate will decompose on heating and reversibly converted to an amorphous dihydrate when heated at 88 degree celcius at 2 torr.

Manufacturing Process

The production processes of borax pentahydrate are similar to borax decahydrate. Borax obtained from lake brines, tincal, and colemanite is separated from the constituent salts. The hot liquor obtained is consisted of borate and potassium salt (KCl). To remove the potassium salt, the insoluble solid particles are filtered out 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. The liquor is evaporated and refrigerated to crytallize borax decahydrate. Borax pentahydrate will be produced by dehydrating borax pentahydrate.

The Uses of Borax Pentahydrate

Borax pentahydrate applications are mostly the same as borax decahydrate. It can be used as cleaning agent, adhesives, cosmetics, and antifreeze. Borax pentahydrate can also be added to fertilizers to provide boron as a nutrient to the plants.

Ceramic Industry

Borax pentahydrate is used to increase scratch resistance as well as chemical resistance of ceramics & enameled appliances. The usage of borax in ceramic & enamels industry results in a smooth & strong finished product.

Glass Industry

Borax Pentahydrate is used to control the network formed by glass melt and increase the strength of final product.

Detergent Industry

Borax pentahydrate is commonly used to manufacture sodium perborate, which is one of the main bleaching agent in laundry powders.

Other Application

Borax decahydrate is also used for waxes and it can also be used as a car antifreeze formulation.

Hazards Identification

Hazard Warnings: Borax pentahydrate 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 pentahydrate
CAS No12179-04-3
Molecular Weight291.35 g/mol
H.S Code28401900
Synonymborax pentahydrate, Etibor48


Appearance-White crystalline, granule or powder
Purity%99.90 (min)
B2O3%47.76 (min)
SO4ppm135 (max)
Clppm70 (max)
Feppm5 (max)
Na2O%21.25 (min)
Insoluble in Waterppm150 (max)
Melting Point°C741