culmin New preselvative search

By Huck DeVenzio Arch Treatment Technolosies

DECENTLY, Arch Treatment ATechnologies.

Inc. announced the development of a new type of pressure treated wood, named Wolmanized Lr (spoken L-cubed) Outdoor wood. It is protected by a preservative that contains no metals, not even copper, and is thus carbon-based or "organic."

The development of any new preservative that is expected to be commercially successful involves a long series of scientific, marketing, production, and safety considerations. This process is especially tortuous when the product is the first of its type.

In the case of Wolmanized Lr wood, the search began nearly a decade ago with the desire to find an alternative preservative that did not rely on metallic ingredients. Metals such as trivalent chromium, arsenate compounds, and copper are excellent deterrents to termite damage and fungal decay, but market preferences led to a movement away from metal-based preservatives. In the 1990s, preservative formulations were found that do not contain arsenates or chromium. The next step was one that did not need copper.

Finding effective non-metallic fungicides and insecticides is not difficult; there are many already registered with the EPA for applications other than wood treatment. The magic comes in determining a combination of compatible existing pesticides which:

. inhibits the necessary range of wood-destroying organisms, is effective in multiple species of plentiful wood, has no unacceptable properties. can be used and handled safely, . and can be economically manu- factured and injected into wood.

The combination must also last for decades, a relatively easy criterion for metals but not for carbon-based components, which can be quicker to degrade.

Testing of candidate preservatives is done in laboratories and field sites under extreme conditions to accelerate recognition of any shortcomings. Small-dimension stakes, which are more vulnerable to deterioration than common-sized lumber, are placed in environments known to harbor aggressive fungi and termites. At any time, Arch and its affiliates monitor about 50,000 test stakes in the ground, encompassing different conditions, wood species, preservative compositions, and retention levels. Performance of candidate preservatives is compared with that of proven formulations to predict long-term effectiveness

For Wolmanized Lr wood. results have been accumulated for eight years from demanding test plots in locations including Hilo, Hi., and Gainesville, Fl. The American Wood-Preservers' Association typically requires at least three years of acceptable data before listing a preservative in its standards. An information packet is being prepared for AWPA review. Listing will be sought for southern pine, ponderosa pine, red pine, Douglas fir, hem-fir, and several other species of lumber as well as southern pine and Douglas fir plywood. The wood has been issued an evaluation report from the International Code Council.

^The preservative in Wolmanized LJ wood consists of a precise mixture of three organic ingredients: propiconazole. tebuconazole, and imidacloprid. Together, they provide effective protection for wood in out-of-ground applications, e.g., decking, r4ilings, fence boards, and molding. Lr wood is not recommended for in-ground components such as embedded deck or fence posts; copper-based preservatives like copper azole should be used for these applications.

Without copper, there !s no galvanic reaction between Lr wood and metal hardware. Thus a significant source of fastener corrosion is eliminated. (Nonetheless, fasteners must be appropriate for location and conditions.) Also, the green color imparted by copper preservatives is not present, so color interference is not a concern when painting the wood.

This lack of color could pose one potential problem-without noticeable difference between treated and untreated wood, there is a risk of mixing inventories and of customers doubting adequate treatment. To avoid this, treaters will add a colorant to the treating solution for identification purposes.

Tests have shown that organic preservatives performed better when a water repellent was present, so built-in water repellent is part of the treatment ofLr wood.

Wood has been treated with propiconazole/tebuconazole/imidacloprid since early 2006 by Everwood Treatment, Spanish Fort, Al., for specialty use as painted molding and trim. The first company to produce Wolmanized Lr wood for general use was Mid-States Wood Preservers, Simsboro, La., in February. By the end of June, there are likely to be several active producers, with others starting up as dictated by consumer acceptance and dealer interest.

Non-metallic preservatives are expected to be introduced by other chemical manufacturers as their testing and verification progresses.

- Huck DeVenzio is manager oJ marketing communications at Arch Chemicals, developer of wood treatments including preservatives, .fire retardants, mold inhibi-tors, and water repellents; www.wolmaniz.edwood .com