Gardening Articles: Landscaping :: Yard & Garden Planning

Wood Preservatives (page 3 of 3)

by Alex Wilson

Safer alternatives

The quest for safer wood preservatives has led to two very promising new products. Neither of these products contain the EPA-classed hazardous chemicals arsenic and chromium, so they are more environmentally sound than CCA. Both alternatives protect wood from decay and insect attack as effectively as CCA, according to their manufacturers, and both remain effective from 30 to 60 years or 5 to 10 times longer than untreated wood.

Chemical Specialties, Inc., introduced ammoniacal copper quaternary compound (ACQ) in the early 1990s, and markets it nationwide as ACQ Preserve. Like CCA, wood treated with it is a light green color and accepts stains readily. Also like CCA, hot-dipped galvanized or stainless steel nails, fasteners, and fittings are recommended because preservative chemicals are corrosive to standard hardware.

Another company, Kodiak, Inc., produces and markets wood that is pressure-treated with copper dimethyl- dithiocarbamate (CDDC). The treated wood is brown rather than greenish like CCA- and ACQ-treated wood. This chemical protects wood as well as the others, but is supposedly less corrosive to fasteners.

The other two CCA manufacturers--Hickson and Osmose Corporation--have developed copper-based CCA alternatives, but they are not marketing these actively in the United States.

Both ACQ- and CDDC-treated woods cost somewhat more then CCA-treated wood and are not yet available in all areas.

Safety precautions

Always wear gloves when applying a preservative, or when working with pressure-treated wood. If sawing, wear a dust mask to prevent inhaling sawdust. After treating cut ends with paintable preservative, wipe away any residue or precipitate that is visible. Never burn scraps or sawdust of treated wood, and only dispose of waste wood at landfills.

Alex Wilson is the editor and publisher of Environmental Building News.

Photography by John Goodman.

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