Are borates the o miracle preservative?

[tOUR years ago. CCA-treated I-' wood had just disappeared from residential applications. Copper-based preservatives were angling to become the heir apparent. Yet the markel noted their higher cost and corrosive-

Borates: Perception vs. Reality

By Vince Opaskar Quality Borate Co., Cleveland, Oh.

There are two realities that govern the usage of borates in pressure ffeated wood: the common perception and the legal rule. Unfortunately, the legal rule trumps the perception.

The common perception amongst the public is that borates quickly get "washed out" from the wood in a little bit of rain. Because of this, the rules for use of borate treated wood restrict the usage category to UC2 level. The UC2 level of usage is defined by the American Wood Preservation Association as "above ground, interior construction, damp (conditions)." By definition, since there is no flowing water running over the borate-treated wood, there will be no losses of borates.

Again, by definition, the content of borate must be above either 0.17 or 0.28 lbs/cu. ft. for Non-Formosan/Formosan termites, respectively.

The AWPA leaching test, Ell06, uses treated wood cube block samples, 0.75 inches on a side, and submerges them under water while stirring the water for 14 days. This is a pretty rigorous test. It is no surprise that borates do not survive the test and still conform to the loading levels cited above. Thus. thev are assigned to indoor, essentially dry conditions of usage. Then again, better to err on the side that protects the consumer, even though the test is a lab test that in no way represents the real world. ness to fasteners.

In a recent paper presented last year by Mark Manning of USB/Rio Tinto, mini-bundles of 2x4s (four high and four across) were subjected to 12" of rainfall with three types of rain/soaking cycles. Anywhere from t5Vo to 377o of the borate content was. in fact, leached out. Again, a good test but not the real world of house construction.

A large chunk of wood goes into common house outside decking. Borate treated wood will not work in this application (Usage category uc3).

The closest application is log homes. The logs are borate treated and the warranty states that the logs must be coated every year to keep the warranty in effect. The added coating prevents the borate leaching.

If the wood is pressure treated up to the cited loading levels, and used in interior dry applications, it will be warranted by the treater for 30+ years. If the borate never leaves the wood. it could be eood for 100+ years!

What dealers and treaters really seemed to want was a preservative with the price and performance of CCA, but one that could be deemed environmentally friendly.

Some in the industry argued there did exist such a perfect preservativeborates. The chemical was supposedly so non-toxic, you could drink it.

"Most people in the industry will agree that borates are the best way to treat wood in the world," says Jack Rombough, general manager of EnviroSafe+, which got its start in 2000 as EnviroSafe Wood Treatment Products LLC, Fort Myers, Fl., intent on mainstreaming borates.

Borate treatments' archilles heel, however, is that they are solublethey can leach out of wood when sub- jected to water. And so began a mad dash by chemical companies to develop a binder that could prevent borates from leaching.

SILL PLATES remain the top application lor borate-treated wood, particularly in Hawaii, where to protect against Formosan termites, building codes require that all framing and sheathing be treated.

"There were attempts to develop a borate-based formula with a wider end use application," recalls Rick Danielson, Allweather Wood Treaters, Washougal, Wa. "Attempts were made to encapsulate the borate in wood using sodium silicate to reduce its exposure to conditions that would leach the borate. Cost considerations to install equipment at the production level and increased treatment costs seem to be some reasons that this 'miracle borate' did not advance within the industry."

In addition, the industry learned that permanently locking borates into wood wasn't necessarily a good thing. "If borates stop migrating, they stop killing the fungi and insects," says Rombough. "Borates don't kill on contact, like spraying on a can of Raid. They act as a drying agent; they dry out the insides of an insect so it can't eat any more."

"If you fix borates permanently in the wood, experience has shown us that the wood preservative will not be effective," agrees Dick Jackson, president of Pacific Wood Preserving Cos.. Bakersfield. Ca. "The borate needs to be mobile in the wood in order for it to be efficacious against decay and termites. It may be possible to develop a semi-fixed borate where the diffusion process is greatly slowed down. So far, no developer of this style of borate wood preservative has opted to commercialize it, however."

While its solubility may prevent borates from becoming an all-purpose super-treatment, "that same characteristic of preservative mobility also helps borates diffuse throughout the wood after treatment to effectively serve its protective purpose," says Danielson. "The end use of the product is quite specific and limited: a service condition in above-ground applications that is protected from continued exposure to water."

Indeed, above-ground, weatherprotected applications are suggested by the majority of companies that sell borates, including leading producer Osmose and even Bluwood, one of the firms that developed a waterrepellent additive to deter moisture absorption.

In addition to framing and sheathing, EnviroSafe+ is sold for exposed, above-ground uses, such as decking, fencing, siding, and playground equipment.

But Rombough confesses, "It's not the holy grail. We cannot keep borates in wood forever. We retard the leaching of borates to the extent where [the wood] becomes a useful product. The main ingredients of our polymer binder are meant to link up with DOT borates to make them more effective."

EnviroSafe+ offers a 40-year transferrable warranty. Still, Rombough admits, "in a very, very wet situation, you have a problem. That said, in five years. we have not had a major issue of failure. And, even if it leaches, it will not harm sunoundines. Boron is used in fertilizer, so it makes lawns green."

Allweather's Danielson thinks borates have remained a minor player for a reason. "While some may think that a non-leaching borate would be a 'miracle' wood preservative. it doesn't appear that the major preservative manufacturers are spending their R&D dollars to pursue that technology," he surmises. "Clearly the trend seems focused on carbon-based preservatives or micronized technology of known decay preventative components. From my perspective, borates have a limited, but very effective use, and seem likely to remain in that catesorv."