Field Tests on Wood Dethiaminized for Protection Against Decay

Wood-destroying fungi need thiamine (vitamin B1) as a growth factor. Earlier laboratory tests demonstrated that wood treated to destroy thiamine had decay resistance. Field tests reported here indicate that at a nominal cost of chemical and minimum handling, wood to be used above ground (but where conditions favor decay) can be effectively protected against decay by dethiaminizing. Several series of tests have been underway for several years. A typical one was on 1 by 6 by 18 inch panels, pressure treated with 0.5 percent aqueous ammonia. Following treatment the specimens were steam heated for 2 hours at approximately 200?F. The treated specimens and untreated controls were exposed in close-piled stacks that allowed ingress of rainwater into and between the panels and retarded its loss. Thus optimum moisture for decay was provided longer after wettings. The condition of these panels after 8 years exposure was judged very good. After 3 years the untreated controls were unserviceable because of decay. The process is attractive because the treated wood contains no residual chemical, it is clean and paintable, and probably presents no problem for gluing.

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