Protect investments and meet demands 

U.S. Borax Borogard® ZB protects wood and wood composites from destroying organisms, rot, decay, fungi, and subterranean termites. Although effective against insects and fungi, Borogard ZB is safe for people, pets, and the environment. Its biostatic properties, low cost, and excellent safety attributes make Borogard ZB the leading wood preservative treatment available.


Borogard ZB

2ZnO · 3B2O· 3.5H2O
Zinc Borate

Made In


What can Borogard ZB do for you?

Borogard ZB is used to protect engineered wood products such as oriented strand board (OSB) and wood-plastic composites (WPCs) as well as plastic and rubber products. Independent laboratory and field studies carried out by universities and government testing facilities have shown that WPCs treated with Borogard ZB resist the ravages of a range of wood-destroying organisms in above-ground uses, including:
  • Decay-resistant siding, roofing, and millwork
  • Termite-resistant sheathing and subflooring
  • Commodities for export to high-decay-hazard regions
As an additive, Borogard ZB can control the growth of white and brown rot decay fungi. As a wood preservative, it also helps to protect against damage caused by wood-destroying insects, including Formosan subterranean termites

Borogard ZB for cost-effective, comprehensive wood preservation and protection

Borogard ZB's performance goes beyond its broad-spectrum efficacy against all wood-destroying organisms.
  • Borogard ZB is a completely reacted zinc borate that is distributed homogenously throughout the product. Its protection is continuous, despite any surface abrasion, end cuts, and sanding that occur during installation. 
  • The product is thermally stable under WPC manufacturing conditions and is easy to introduce into existing manufacturing processes.
  • Particle size and shape are optimized to reduce solubility in water, making Borogard ZB resistant to leaching and weathering and increasing its proven effectiveness over a longer period than competing products.
  • As a synergist, Borogard ZB can boost the performance of hindered amine light stabilizers (HALS), which are used to protect WPCs against UV degradation. Slowing down the degradation of WPCs’ plastic components further minimizes exposure and degradation of the wood components.
  • Borogard ZB is the most cost-effective protection available for WPCs and other composites.




Wood Protection and Biocides

Borates and boron compounds are used in the creation of affordable, durable, and environmentally safe wood and wood products in order to protect them from fire, fungi, and pests.

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Polymers and Coatings

Polymers can ignite and burn easily which is why flame retardant additives are often required to meet safety standards. One of the many commercial applications of borates is fire retardancy.

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Chemical and Physical Properties

Formula weight: 434.66

Appearance: White, odorless, powder

Median particle size: 7 microns (Sedigraph)

Solubility: Less than 0.28% in water at room temperature

Stability: Thermally stable up to 290°C. Can be hydrolyzed by strong acids and bases

Crystal density: 2.79 g/cc

Chemical Composition (Theoretical)

Boric oxide, B2O3: 48.05%

Zinc oxide, ZnO: 37.45%

Water of crystallization, H2O: 14.50%

Containers: Multi-wall paper bags with a polyethylene moisture-resistant film barrier, 50 pounds (22.7 kg) net; 55 pounds (25 kg) net; or superbags with polyethylene liner, 2500 pounds (1134 kg) net

Stability: When stored under normal conditions of temperature and humidity, Borogard ZB is chemically stable and shows no tendency to cake.

Borogard ZB has been used in North America for years, with a broad spectrum of efficacy and low acute mammalian toxicity. However, WPCs treated with Borogard ZB are not suitable for ground contact and must be protected with a water-repellent coating when used in exterior applications (eg, joinery and siding).

Borogard ZB is leach resistant—only sparingly soluble in water at room temperature (< 0.28% w/w). It contains no organic components and does not require the use of organic solvents because it is applied as a dry powder.

By adding Borogard ZB before or during the blending process, you can achieve a thorough and uniform distribution of the chemical throughout the composite material. Efficient distribution of the preservative in the manufactured board can be confirmed by chemical assay.

Borogard ZB is chemically stable to 290°C and is not altered during normal wood composite manufacturing processes. Composites treated with appropriate levels of Borogard ZB generally retain their natural appearance and strength. Ferrous metals, plastics, rubber, putties, bituminous solutions, other sealants, primer, and finish paints are not adversely affected by wood composites treated with Borogard ZB.

WPC manufacturers should determine the Borogard ZB loadings for their treated products and end-use applications. Borogard ZB loadings should not exceed 8% (w/w), and loadings in excess of 1.5% (w/w) might require additional adhesive binder to compensate for possible effects on strength.

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Contact our sample fullfillment team.

We’re here to help with your boron needs.

Contact sales

Our regional sales teams are ready to help with your purchase

Learn More

Get technical support


Your resource for borate-related technical and laboratory services across every industry

Learn More

Request a sample

Get small quantities of our products to ensure you have what you need for your formulation or process

Learn More

BoroGard ZB in Action

The Brilliance of Borogard ZB
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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 650 customers with more than 1,800 delivery locations globally. We supply around 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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