Dual Borate-Creosote Treatment Key to Preserving Railroad Ties

:: Monday, June 3, 2024 :: Posted By Emmanuel Laval

For decades, a dual borate-creosote preservative treatment has provided railroad crossties with long-lasting protection.

Recently questions have surfaced concerning boron’s effectiveness—particularly its potential for leaching. However, research continues to reinforce that dual treatment significantly extends the lifespan of railroad ties, especially in decay-prone areas.

With the right concentration and application, railroad tie producers can reduce replacement costs, ensure longevity, and keep critical transportation infrastructure safe.

Doubling the lifespan of railroad crossties

According to a recent paper published in Crossties magazine, “Dual treated ties last twice as long as ties with only the primary preservative in high decay hazard areas.”

What makes dual treatment so effective?

Dual treatment protects both the outer and inner layers of wood crossties—combining boron and creosote—to form a powerful preservative formulation.

First, producers treat the tie with a disodium octoborate tetrahydate (DOT) product such as Tim-bor®. Because crossties are almost always made from a hardwood species, penetrating to the wood’s core is more difficult. But borates are highly water soluble, making deeper diffusion easier.

Afterwards, the crosstie receives a pressure treatment of creosote (in certain situations, copper naphthenate). Creosote stays closer to the wood’s surface, equipping the wood with outer layer protection.

If only creosote is applied, a tie’s service life typically runs 8 to 25 years. When crossties receive both borates and creosote, the dual protection extends the active lifespan to around 40 years.

Of course, humidity and warm weather are key factors in longevity, causing faster degradation than wood found in dry, cold climates.

Benefits of boron in railroad crossties

Boron compounds can be a safe, effective, and cost-efficient choice for wood preservation and protection. They prevent moisture-induced decay, fungi-caused wood rot, and pest-related damage. In crossties, borates offer special advantages over other preservatives.

Reinforces strength
Borates’ ability to diffuse throughout wood prevents heartwood decay, a leading cause for crosstie failure. Left unchecked, fungi reduce the wood’s mass, lowering the tie’s strength and ultimately causing failure.

Slows “spike kill”
Degradation can also occur near the steel spikes securing rails to the wood ties. If that happens, the spikes may loosen, causing the rails to shift and in severe cases, train derailment occurs. Adding borates to the wood greatly lowers the risk of “spike kill.”

Safeguards from termites
Even after crossties are retired, borates safeguard the wood from termites and prevent these invasive pests from spreading to healthy wood during transportation.

Read more about how borates protect railroad crossties

U.S. Borax: Your source for high-quality borates

The importance of a proper dual borate treatment can’t be understated. Dual treatment is not only economically efficient, but also critical to safe and reliable rail infrastructure.

The right borates concentration, followed by a creosote treatment, can significantly extend railroad ties’ service life, even in areas prone to decay.

Our technical experts can help ensure your formulation meets American Wood Protection Association standards for protection and preservation. Because U.S. Borax products are subjected to robust quality management practices, you can trust that you’ll receive consistent, high-quality borates that perform well in your crosstie application.

Contact us

Have questions about borate-based treatment for railroad crossties? I’ll be at the upcoming 2024 Railroad Tie Association Summer Field Trip in Birmingham, Alabama.

If you’re unable to attend, we encourage you to contact our technical team for more information.



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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