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Advertising supplement provided Jeld-Wen Windows & Doors

The 300-member, Stockholm-based International Research Group on Wood Preservation this year will disseminate roughly 150 technical documents on subjects as arcane as “Effects of methylene bisthiocyanate on morphology and ultra-structure of a sapstain fungus,” and as topical as “Environmental Impacts of CCA (chromated copper arsenate) Treated Wood.” In February, 2004, the Florida Interdisciplinary Center for Environmentally Sound Solutions (FICESS), under the sponsorship of the National Science Foundation, will host several thousand attendees to the “Environmental Impacts of Preservative-Treated Wood Conference in Orlando.”

Because environmental restrictions are creating changes in the wood preservation landscape, and because of the emergence of new treatment technologies, this continuing education piece will look at wood preservation—from the perspective of the U.S. millwork industry—and discuss water-based processes which, though they have been around for nearly a half century, are likely to become industry standards in this era of environmental sensitivity. It will look at alternative treatment methods that have become standard throughout the industry standards and describe the new water-based process which soon will replace existing treatment methods for all of the product line of the manufacturer.

 

Top: L-joints during exposure in Hilo with differences in mold on paint. Bottom: Greenhouse setup of L-joints for artificial spraying of water.

Treatment methods generally differ by wood species, but, in general, the replacement cost of treated wood over its lifetime is much lower than that of untreated wood, which has a shorter useful life, says the American Wood Preservers Association (AWPA).

Although not used in millwork, chromated copper arsenate (CCA), which serves as a fungicide and insecticide (and which gives the green cast to outdoor decks, picnic tables and playground equipment) is topical because the U.S. Environmental Protection Agency (EPA) has announced a ban of its use. Fearful of the effects of arsenic exposure, the U.S. will ban CCA products for residential use after January 2004. The European Commission has announced a partial prohibition on the use of CCA-treated timber, to take effect after June 2004. The reasoning: scientific studies suggest that, over time, arsenic slowly leaches from CCA-treated wood products, the rate dependent upon rainfall, soil PH and the age of the structure. EPA Administrator Christie Whitman announced in February 2002 a “voluntary” decision by the lumber products industry to move from arsenic-based preservation techniques to alternative wood preservatives. The EPA is not recommending, however, that existing structures or surrounding soils be removed or replaced.

As is the case with outdoor lumber manufacture, millwork preservation incorporates water repellants, fungicides and insecticides in the manufacturing process. In most millwork preserving systems “active ingredients” are carried into the wood by petroleum-based solvents, most typically applied today through a “dip” method, no more complicated than it sounds, in which untreated lumber is dipped into a tank of preservative to make the wood resistant to decay and insect infestation.

Effective water repellant preservatives retard the impact of moisture on wood and, thereby, help reduce dimensional changes in the wood.