Interlaboratory Testing of Wood Preservatives Using Astm D1413-61

Toxic thresholds for three wood preservatives determined at the Western Forest Products Laboratory, Vancouver, Canada, and at the U. S. Forest Products Laboratory, Madison, Wisconsin, showed considerable interlaboratory variation. At the Vancouver laboratory, toxic thresholds were always lower, and wood weight losses for the untreated control blocks were higher than the corresponding data for the Madison laboratory. Toxic thresholds calculated from both oven-dry weights and conditioned weights were similar within each laboratory. Ethylene oxide was unsuitable for the sterilization of creosote-treated wood because of the resulting increase in its toxicity to fungi.