There’s a Superhero Beneath Your Feet

Imagine a trail dipping below a steep valley edge surrounded by lush, verdant greens. A brook chatters below and in its soft watery tones invites hikers to a moment of relaxation and communion. The breeze is soft and sweet as the leaf canopy dances in unison overhead. It is idyllic and accessible because of the wooden boardwalk solidly supporting each who visit this natural wonder.

This boardwalk and others like it can be found in many natural areas. But it is made possible by pressure-treated wood, a building material that when processed with the correct preservatives, often outlasts and outperforms durability estimates and usefulness before it can biologically deteriorate.

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Time in a Bottle: Finding New Life for an Old (Yet Reliable) Test Method

The simple soil bottle presents an extremely useful tool for predicting performance of preservative treated, modified or naturally durable woods. The methodology was developed in the 1940s exclusively for evaluating wood preservatives against wood decay fungi. It has been adapted over several decades to include naturally durable woods, wood plastic composites, and engineered wood products, and we use it constantly here at the Forest Products Laboratory (FPL).

The basic premise of the soil bottle is a material is presented to an actively growing fungus in an otherwise sterile environment. The resistance of the material to fungal degradation is determined by comparison to reference materials (non-durable species or treated reference material). The soil bottle also presents an excellent tool for studying basic fungal biology whereby cellular changes in wood during the decomposition process can be analyzed.  The soil presents a refuge for the decay fungus as well as a source for moisture and transported ions relevant to the decay process.

Past, present and future research at FPL is looking at ways of modifying the standard soil bottle setup to be even more useful for the evaluation of wood and wood protectants. Here are just a few examples of where FPL researchers are pushing the boundaries of the standard soil bottle: Continue reading

Fighting Termites with…Shrimp?

Every year, millions of dollars go towards safeguarding wood against its six-legged nemesis — the termite. Although usually associated with southern United States, research has shown that these wood-munching insects can infect wood as far north as Wisconsin. Among the chemical sprays and concrete barriers used to combat termites are an array of copper-based, anti-termite wood preservatives.

Termites in a laboratory setting.

Unfortunately, in addition being bad for termites, the copper in these preservatives may also be detrimental to the environment. Some researchers have posited that copper-treated wood may also be linked to the destabilization and premature failure of metal fasteners. Environmentally and structurally safe alternatives (that can meet the demands of green construction) are becoming high on the eco-friendly consumer’s priority list.

When formulating these new treatments, researchers at the Forest Products Laboratory (FPL) may need to enlist the help of another ten-legged animal — the shrimp. Chitosan, a compound known to deter wood decay fungi and some species of insects, can be synthesized from chitin, a waste product generated during industrial shrimp processing. In addition to being environmentally friendly, production of this “shrimp cocktail” is relatively inexpensive.

Although chitosan’s effectiveness against termites is currently unknown, a new FPL study, in cooperation with Mississippi State University, hopes to find out just how much chitosan-laden wood termites can handle. After determining how the insects react to different concentrations of compound, researchers will see if the termites adapt to the chitosan, and if they do, attempt to uncover the biological processes underlying these adaptations. This in-depth evaluation will even include studying the DNA and RNA profiles of the termite digestive tract.


The termite digestive tract. The hindgut portion can host up to 1 billion microbes per termite.


The termite gut can contain 10 million to 1 billion microbes per termite. Recent studies have shown that a termite’s diet can influence the composition of this microbe community and the termite’s wood-degrading enzymes. By analyzing the genetic profiles of the microbes as the termites consume the chitosan, researchers hope to better understand expression of protein(s) or protein product(s) that are responsible for any resistance to the compound.

In addition to verifying the utility of chitosan as a termiticide, the 5-year-long project will offer insight into other aspects of wood preservation. The genetic profiles alone will provide future studies with a wealth of knowledge, and shed more light onto the mechanism of wood degradation by termites.

The information could also be used to improve current approaches to wood protection, further our overall understanding of wood conversion to energy, and may assist in the development of future value-added products.

For more information, please see the Research in Progress publication Effect of Chitosan on the Termite Digestome.


New Treatment Plant Ushers in Next Century of Wood Preservatives

The Forest Product’s Laboratory (FPL) is pleased to announce the opening of a new, state-of-the-art pressure treatment facility to continue the tradition the laboratory has as an innovator in the field of wood preservation. The new, computer-controlled, vacuum and pressure, wood preservative treatment system includes five pressure vessels capable of treating material ranging from small test specimens, to large post and pole sections. Separate systems are maintained for water-based and oil-based preservative treatments.

FPL's Steve Halverson working in the pressure treatment facility.

FPL’s Steve Halverson working in the pressure treatment facility.

The new facility builds on the successes of the past to better the future of wood preservation.

The vast landmass of the United States was forged into a single nation through common ideology, shared destiny, and more than a little help from the railroad system. Supporting these tracks were thousands upon thousands of wooden railroad ties—but supporting these wooden ties were researchers at FPL.

Helping to keep the country’s trains rolling was the pressure treatment facility at FPL. One of the lab’s first objectives was to research better methods to make railroad ties last longer through pressure treatment methods.

Lumber, poles, posts and other outdoor wood products are usually treated with preservatives to prevent decay and insect damage. Pressure treatment is a process that forces a preservative deep into the wood structure. Without pressure treatment, only a thin outer layer of wood is protected.

The equipment can utilize pressures of up to 235 PSI (1620 kPa) and temperatures up to 250 degrees Fahrenheit (121 degrees Celcius). In addition, FPL’s facility features a unique design, allowing for small specimens to be treated in pans within the pressure vessels while the treatment solution is circulated and heated.

Now that the equipment is fully operational, researchers hope to find new ways to optimize the quality of preservative treatments.  By varying parameters such as steam, temperature, vacuum pressure, preservative type, and wood species, FPL hopes to identify cost-efficient treatment schedules that achieve thorough preservative treatment without damaging the wood structure.

The equipment is also critical to the evaluation of new types of preservatives. It can be used to prepare test specimens to study their resistance to biological degradation or leaching. Other applications include accelerated weathering, extracting of chemicals from wood, and elevated moisture simulations.

This new treatment facility has a much wider application than preserving railroad components. FPL invites collaboration with partners from industry, academia, trade associations, and other government agencies to take part in the next chapter of the laboratory’s history, ensure that the research is converted into useful technology, and help support the Forest Service’s mission of caring for the land and serving people.

Visit FPL’s website for more on our Durability and Wood Protection research.