Multi-function cleaning and protection

Polybor® earns its spot in industrial cleaning compounds, fire retardants, and the manufacture of water-treatment chemicals.
Polybor provides protection and is incorporated into many cleaning products.

Protection from Flame and Corrosion

Whether in industrial or consumer settings, Polybor proves effective at reducing flammability, corrosion inhibition, and enhancing cleaning products. The product is highly soluble and can be used to help protect cellulosic materials, including those used in insulation and mattresses, and fabrics from combustion and flammability.


Fire retardancy

Polybor is particularly effective as a fire retardant in cellulosic materials such as wood composites, cellulose insulation, cotton batting, paper, and fabric. After oxidation reactions in the combustion of such materials, borates produce a charring action that suppresses smoldering and diverts decomposition products that can smolder and combust. Fire retardant lumber, plywood shingles, and shakes can be made by vacuum or pressure impregnation with Polybor solutions.

Polybor solutions can also be applied to fabric by direct spraying or dipping. In this way, the product can be used in fire retardant treatments for clothing, drapes or curtains, rugs, ironing board covers, fireman’s clothing, fabric heat deflectors for stoves or fireplaces, and fire-smothering blankets. Solutions can also be used in the manufacture of fire-retarded paper products, such as high-gloss or file-storage boxes.

Aqueous and non-aqueous systems

Polybor can also be incorporated in aqueous and non-aqueous systems for corrosion inhibition, lubrication, or thermal oxidative stabilization. Corrosion inhibition makes it useful in the manufacture of water-treatment chemicals.


The product’s ability to aid emulsification of oils and to act as a soft abrasive makes it ideal for use in cleaners. When combined with polyhydroxyl compounds, Polybor can be used for viscosity control. Add Polybor to formulations used to clean hard surfaces (eg, metals, glass, ceramics). The product is also used as an additive in hand cleaners, polishes, and waxes, and industrial/institutional cleaning compounds.

Polybor, along with boric acid, is a principal boron compound used as the flame retardant in resin-bonded wood composite boards such as chipboard, waferboard, and fiberboard.


Available Grades

Polybor is a mild alkaline salt. It takes the form of an amorphous fine white powder that is readily soluble even in cool water. When dissolved, the product results in a supersaturated solution with a high boron concentration.

When used in flame retardants for paper, the amount of material required can result in a stiffening effect. This effect can be overcome by the inclusion of a softening agent (eg, urea) in the treating solution.

Aqueous solutions of Polybor show a slight decrease in pH with increasing concentration. Saturated solutions are nearly neutral. Details of Polybor's hydrogen ion concentration can be found in the product data sheet.


Chemical and Physical Properties

Formula weight: 412.52

Appearance: Fine, white powder

Solubility: Polybor's solubility in water (as Na2B8O13·4H2O) increases with increased temperatures, with the most significant changes in solubility occurring at or below room temperature. For details, download the product datasheet.

Stability: Polybor shows little tendency to cake except after prolonged storage or if it severely wetted by rain or substantial water penetration. It can also absorb moisture if exposed to a humid environment and can form crystals of sodium pentaborate when exposed to water.

Product Specifications

Boric oxide, B2O3: 66.2 to 69.0%

Sodium oxide, Na2O: 14.0 to 15.1%

Containers: Products may be available in bulk, IBCs, or small bags

U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 500 customers with more than 1,700 delivery locations globally. We supply 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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