Wood Preserving

People have been coating wood with crude preservatives, such as tar and pitch, for ages. Chemicals and processes developed during the nineteenth and twentieth centuries, however, have resulted in techniques for preserving wood for 35 years or more. Untreated wood exposed to the elements typically lasts about three years. Perhaps the greatest industry innovation during the 1900s was the high-pressure chemical treatment process, which accelerated wood's absorption of preservatives and increased the treatment's depth. During the early 2000s, 95 percent of all preserved wood was treated using this process. Southern yellow pine accounted for 85 percent of all treated wood; the remaining 15 percent was spruce-pine-fir, hemlock, Douglas fir, cedar, inland species of Ponderosa pine, and Brazilian pine. Demand for treated hardwoods continued to be quite low.

Total value of shipments reached $5.8 billion in the wood preservation industry in 2007, according to the U.S. Census Bureau. About 512 establishments employed 13,298 workers, 79 percent of which were production workers. Figures based on Dun and Bradstreet's 2009 Industry Reports showed that Alabama accounted for the largest percentage of the nation's sales, followed by South Carolina, Virginia, Georgia, and Louisiana. Alabama, Georgia, and North Carolina were the top three states in terms of employment in the industry.

The majority of wood products are treated with water-borne preservatives, the most common being chromated copper arsenate (CCA), ammoniacal copper quat (ACQ), and ammoniacal copper zinc arsenate (ACZA). Materials for decking, fences, gazebos, playgrounds, and the like are usually treated with this method. Pentachlorophenol, an oil-borne preservative, is used on utility poles and glued-laminated beams for vaulted ceilings.

Wood preservers had to adjust to new environmental restrictions in the late twentieth century. In 1990 the Environmental Protection Agency (EPA) identified the byproducts of wood preserving processes as hazardous waste and began regulating the industry in 1991. Naphthenate and other substitutes increasingly offered viable alternatives to preservatives that spawn high-cost toxins. In 1996 Koppers Industries, an industry leader, reported ongoing problems with site and groundwater contamination from wood preservatives and experienced EPA violations at many of its facilities. The company installed additional pollution control and monitoring devices at various facilities and participated in extensive cleanup operations.

The industry continued to work against negative publicity about pollution problems, especially research that showed that arsenic, in particular, leaches into the ground and water system as well as rubs off on those handling treated wood materials. The industry was also seeking alternative means of disposal of used treated materials, because burying them in a landfill, as well as burning the materials, releases chemicals into the ecosystem. One of the ways of dealing with the problem involved reconstituting used treated woods into particle board. Researchers also worked to find new ways to treat wood that were more environmentally friendly, such as using heat, mud, tung oil, and microwave technology.

Another new technology in the treated wood industry was the use of a protective coating called Bluwood. The preservative, which leaves a blue color on the wood, contains no harmful chemicals, according to Robert Seaman of Bluwood International. Seaman told TTJ--The Timber Industry Magazine, "We have found a way to not only keep the borates in the wood, but to keep the moisture content constant as well." Seaman added that the coating has a lifetime guarantee and contains no harmful chemicals.

More than half of the establishments in this industry were small companies with fewer than 20 employees. About 15 percent of industry employees worked as assemblers, fabricators, and hand workers. Other occupations included sawyers; machine feeders; blue-collar supervisors and laborers; wood machinists; truck and tractor operators; freight and material movers; managers and executives; and coating, spraying, and painting workers. According to the 2008-09 edition of the Occupational Outlook Handbook, "Despite the abundance of plastics and other materials, wood products continue[d] to be useful and popular" in the late 2000s.

A top company in the industry in the late 2000s was Koppers Holdings Inc. of Pittsburgh, Pennsylvania, which made carbon compounds and treated-wood products for railroad, construction, steel, and other industries. The firm had manufacturing operations in North America, Asia, Europe, and Australia and recorded sales of almost $1.4 billion in 2008. Other industry leaders included Owens Corning (Toledo, Ohio); KMG Chemicals Inc. (Houston, Texas); Robbins Manufacturing Co. (Tampa, Florida); Tolleson Lumber Co. (Perry, Georgia); and Walker-Williams Lumber Co. (Hatchechubbee, Alabama).