Borate treated wood is on the rise as a safe and long-lasting method to protect homes from wood destroying organisms. There are several types of borate wood preservatives used to treat solid wood, engineered wood composites and other interior building products like studs, plywood, joists and rafters.

Borate treated wood has been used successfully for more than 50 years in New Zealand, for a decade in Hawaii—specifically to combat the voracious and highly destructive Formosan subterranean termite—and increasingly throughout the mainland United States. Borates prevent fungal decay and are deadly to termites, carpenter ants and roaches—but safe for people, pets and the environment. Borates interfere with termites’ metabolic pathways when ingested through feeding or grooming, effectively killing them. Surviving termites avoid the protected wood products. Biocidal applications outside of wood protection include use as a fungicide and preservative in paints and coatings (in can and dry film), as a fungicide in polymers and rubber, and as a biocide for plastic and rubber.
Wood preservative


Borates create an affordable, durable, safe treatment system to protect wood homes from termites and decay.
Borates in a wide range of applications contribute to energy-efficient building practices that are safe for people, pets and the planet. Borax products are formulated for optimal efficacy in different applications.

Borax and wood preservative

Protecting Your Investment

Boron compounds offer some of the most effective and versatile wood preservative systems available today. They combine the properties of broad-spectrum efficacy and low acute mammalian toxicity. Oxides of boron, the active ingredients in boron systems, are ubiquitous within the environment, are essential plant micronutrients and are added regularly to agricultural land as fertilizers.

Wood treatment

Protecting Wood Naturally

One of the most important functions boron serves is to keep the world green. All plants—from fields of cotton to groves of Douglas fir—depend on trace amounts of boron to thrive. Although boron is essential for plants, and nutritionally important for humans, it also works to control insects and fungi that attack wood. Treating solid wood and engineered wood products with borates—from framing lumber and telephone poles to furniture and wood-plastic composite decking—provides safe, affordable, long-lasting protection against wood-destroying pests. Borate-treated wood products include:

  • Lumber and plywood
  • Oriented strand board
  • Siding
  • Engineered wood
  • Wood plastic composites (WPC)
  • Millwork, windows and doors
  • Furniture
  • Telephone poles
  • Railroad crossties
  • Log homes

Boron in Wood Protection and Biocides

Engineered Wood

Engineered wood products that replace solid sawn lumber can be treated with borates for long-term protection. Depending on the material, engineered wood can be treated with Borogard® ZB during manufacturing, pressure treated after manufacturing, or assembled with pretreated components.

Engineered Wood

Lumber and Plywood


Wood is among the world’s most sustainable building materials. In fact, trees’ ability to absorb carbon dioxide and emit oxygen make wood the only building material that is renewable and has a positive impact on the environment. Treating lumber and plywood used for homes and other structures with borates provides protection from termites—including the voracious Formosan termite—decay fungi, carpenter ants, and wood boring beetles. Lumber and plywood can be treated through a vacuum pressure process, or by dip-diffusion. Pressure-treatment is used most often in North America while other parts of the world rely on dip-diffusion. While both methods are effective, treatment standards may differ according to location.

Flame Retardant

Flame retardant-treated lumber and plywood have often been successfully used in structures exposed to temperatures less than 100°F (38°C). The usual method of treatment of dimensional lumber and plywood is by vacuum/pressure impregnation with aqueous solutions of flame retardants. Flame retardant plywood can also be produced by impregnation of individual veneers, often just by soaking, prior to assembly and gluing into plywood. It is necessary to ensure compatibility between the flame retardant additives and the adhesive system to obtain strong bonding. Boron compounds by themselves are effective flame retardants in lumber or plywood. They can be used in conjunction with other flame retardant chemicals including ammonium sulfate, diammonium phosphate or zinc chloride.

Lumber and Plywood

Millwork, Windows and Doors

Joinery, or millwork, has traditionally been preserved with solvents, which dry relatively quickly, and do not raise the wood grain or cause dimensional changes. Solvent-based systems, however, are under heightened environmental scrutiny due to their release of volatile organic compounds, a precursor to smog. Waterborne borate treatments provide a more environmentally sound solution for protecting millwork, windows and doors.

Millwork, windows and doors

Oriented Strand Board

The forest products industry is undergoing a fundamental shift from old-growth forests to short-rotation, plantation forests. As a result, more builders are relying on wood composites like oriented strand board (OSB) for a wide array of construction materials. Wood composites—like other wood products—must be protected from wood destroying insects and decay fungi. That protection is built in by treating wood composites with Borogard ZB during the manufacturing process. Borax supplies Borogard ZB for protecting wood composites such as OSB.

Oriented strand wood

Wood Plastic Composites (WPC)

Wood plastic composites or WPCs—the combination of wood and plastic—are gaining popularity as a safe, environmentally sustainable and long-lasting material for use in outdoor decks, fences, railing and window frames. Today, WPCs can be found everywhere from National Parks to your neighbor’s backyard.

WPCs offer a wide range of advantages over alternatives such as pressure-treated lumber and naturally durable cedar or redwood: weather resistance, long service life and lower maintenance, to name a few. These products also play a role in developing a more sustainable future: many WPCs use recycled plastic and wood as raw materials in the manufacturing process.

Tests of WPCs in harsh outdoor exposures have unveiled one potential downside to this miracle material: wood fiber not completely encapsulated by plastic is, by its very nature, food for fungi.

Tests show that, left unprotected, the wood fiber in WPCs may be susceptible to wood destroying organisms such as decay fungi and termites. Standard laboratory tests evaluating the performance of commercially-produced WPCs against decay fungi have exhibited weight losses of between 10-20%. Because typical WPCs have a wood:plastic ratio of 50:50, this loss equates to a reduction of between 20-40% of WPCs’ wood component.

But there is also good news from the laboratory and the field: Borogard ZB—used in preservative treatment of WPCs—provides long-lasting protection against decay fungi.

Wood Plastic Composites (WPC)

20 Mule Team Borax Products

These 20 Mule Team Borax products are developed for wood protection and biocide use.

Ammonium Pentaborate

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Borax Decahydrate

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From reducing melting temperatures in fiberglass production to inhibiting corrosion in fuel additives, Optibor has a multitude of uses in numerous industries. Learn More


Polybor earns its spot in industrial cleaning compounds, fire retardants, and the manufacture of water-treatment chemicals. Learn More

Rio Tinto Borates is a global leader in the supply and science of borates - naturally-occurring minerals containing boron and other elements. Refined borates are essential nutrients for crops. We are 1,000 people serving 500 customers with over 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 east of Los Angeles.  Learn more about Rio Tinto

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