Looking into the Future of Wood Preservation

Carol Clausen and her group are serious about wood as a sustainable and versatile building material. Here Amy Blodgett, Rachel Arango, and Bessie Woodword check soil block samples in their ongoing research.

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Members of the Durability and Wood Protection Research Unit check soil block samples.

The soil block decay test method determines the minimum amount of preservative that is effective in preventing decay of selected species of wood by selected fungi under optimum laboratory conditions. Conditioned blocks of wood are impregnated with solutions, emulsions, or dispersions of a preservative in water or suitable organic solvent to form one or more series of retentions of the preservative in the blocks. After periods of conditioning or weathering, the impregnated blocks are exposed to recognized destructive species of both brown-rot and white-rot wood-destroying fungi.

Speaking about her work, Clausen says that wood’s “increased use in construction minimizes life-cycle impacts of a structure while maximizing carbon storage for the life of the structure.” An upcoming report by Clausen, Frederick Green III, Grant Kirker, and Stan Lebow summarizes presentations and comments from the inaugural Wood Protection Research Council meeting, where research needs for the wood protection industry were identified and prioritized.

As a part of that conversation, Clausen states that chemicals used to protect wood from deterioration by fungi and insects have generally been broad-spectrum biocides that have been discovered by the traditional screening approach. However, a more logical approach is to develop selective and targeted biocides by defining the target first, characterizing that target, and then designing inhibitors based on the mechanism of action of the defined biotarget.

Despite substantial progress in explaining the biochemistry of wood degradation, biochemical targets for fungal inhibition have seldom been described. Discovering the mechanism of preservative tolerance(s) in economically important fungi and insects will enable researchers to design preservative systems that neutralize, block, prevent, and eliminate the preservative tolerance. Development of a genetic database of microbial activity during the process of wood deterioration will offer a better understanding of precisely how and when decay or insect attack begins. A molecular database would provide myriad of capabilities to the wood preservation community. For example, researchers could characterize decay risks for a particular location, define the prevalence of tolerant fungi on a national and international basis, and determine the influence of preservative exposure on the ecology at test plots.

The next generation of novel wood protection methods may incorporate nanotechnology for design or controlled delivery of biocides for improved durability of building materials, with an emphasis on engineered composites. Nanotechnology may also play a vital role in the development of water-resistant coatings and treatments for the prevention of fire. Results from basic research on genetic analysis, biochemical processes, nanotechnology, and characterization of biotargets will lead to technological developments that extend the service life of wood and wood-based materials in all major end uses emphasizing environmentally friendly methods.