Wood is one of nature’s foremost renewable resources. A resource that begins in the form of trees that absorb carbon dioxide and emit oxygen, and ends as construction that outperforms steel for tensile strength, sound absorption, affordability … and beauty.

From modern homes and offices to the wooden furniture within them, borax plays an important role in protecting wood and wood-product construction and materials from fire, fungi, and pests. Borax is even used for historic landmark preservation, such as buildings and ships, for total wood protection.

Borates and boron compounds are used in the creation of affordable, durable, and environmentally safe treatment in a variety of applications:

  • Solid wood
  • Lumber and plywood
  • Oriented strand board (OSB)
  • Engineered wood
  • Railroad crossties (sleepers)
  • Millwork, windows, and doors
  • Mass timber
  • Cross-laminated timber (CLT)
  • Wood plastic composites (WPC)
Formosan termites eat more wood per colony member than any other kind of termite. Fortunately, borate-treated wood is fighting them back, from Hawaii to New Orleans. Borate-treated wood is the leading building material for residential construction in Hawaii—the only state that requires the use of termite resistant construction materials.
Wood treatment

Protection from termites and pests

Wood is among the world’s most sustainable building materials. Yet in many areas, wood construction is hampered by the prevalence of damaging pests such as the voracious Formosan termite.

Treating lumber and plywood used for homes and other structures with borates can help keep those structures safe from such dangers. Termites, carpenter ants, and wood boring beetles—borates prove deadly to them all. Boron wood treatment options for lumber and plywood include a vacuum pressure process (popular in North America) or dip-diffusion. Both methods are effective, although treatment standards might differ depending on location.

Borax and wood preservative

Protection from moisture, rot, and fungi

Borates are extremely effective at protecting wood from decay fungi (wood rot) by combining in solution with groups of biochemicals that are vital to metabolic processes at the cellular level. These combinations are then unable to take part in the metabolic pathway, and so the cells of the fungi starve.

Borates are also highly effective broad-spectrum preservatives, gaining full control over the fungi and insects responsible for the biodeterioration of natural-fiber products. However, borates simultaneously possess very low acute mammalian toxicity, so they pose virtually no risk to people or pets.

Protection from flame

Boron compounds make effective flame retardants in lumber and plywood. Such compounds can be used in conjunction with other chemicals, including ammonium sulfate, diammonium phosphate or zinc chloride, or used alone. Flame retardant-treated lumber and plywood have been successfully evaluated for structural strength and durability at service temperatures per ASTM D5664 and AWPA Standard U1.

Dimensional lumber and plywood are usually treated by vacuum/pressure impregnation with aqueous solutions of flame retardants. Individual plywood veneers can also be soaked with fire retardants before assembly and gluing, so long as compatibility between the flame-retardant additives and the adhesive system is ensured (to promote strong bonding).

Environmentally sustainable product protection

Wood plastic composites (WPCs)—a combination of wood and plastics—are a safe, environmentally sustainable, and long-lasting material for use in outdoor decks, fences, railing and window frames. Found everywhere from national parks to your own backyard, WPCs offer a wide range of advantages, including weather resistance, long service life, and lower maintenance. 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.

Unfortunately, unprotected wood fiber in WPCs can be susceptible to destructive organisms, such as decay fungi. With a typical wood-to-plastic ratio of 50:50, fungi can destroy 20-40% of WPCs’ wood component. To provide affordable, long-lasting protection of WPCs against decay fungi, consider preservation with borates as a wood fungicide.

20 Mule Team Borax Products

These 20 Mule Team Borax products are developed for wood protection and biocide use.
Optibor® MG is the only Optibor grade suitable for pesticide use.

Borogard ZB

Protect wood and wood composites from destroying organisms, rot decay fungi, and subterranean termites. Learn More

Optibor boric acid

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


This industrial, high-performance wood preservative is ideal for protecting rafters, cladding, and joinery against insects and decay. Learn More

U.S. Borax is a proud member of:

Railway Tie Association logo
American Wood Protection Association logo
Western Wood Preservers Institute logo

More about Borates in Wood Protection and Biocides

The Brilliance of Borogard ZB
Wood composite products are increasingly important to the construction industry as builders around the world look for materials that are versatile, strong, an... Read More
Borates and Stradivari: A Sound Science
New research confirms borates and other chemicals used to treat the wood of Stradivarius violins may influence the unparalleled sound quality of the iconic in... Learn More
Borates for Wood Protection: Forest-to-Market
The wood and timber industries rely on borates for environmentally safe options for wood protection. Learn how borates protect, preserve, and extend the life ... Learn More

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.

Copyright © 2022 Rio Tinto. All Rights Reserved.