An Accelerated Wood-Preservative Termite Study

A laboratory test was designed in which pieces of southern pine 3/4 by 3/4 by 2 inches were impregnated with a range of preservative concentrations. A reference weight was made of each block of wood and these were then placed in 3-ounce jars with sandy loam soil and water. Subterranean termites were introduced to cover the top surface of the soil in the jar–about 200. The jars were kept at a temperature of 30?C. and a relative humidity of 62 percent. Since no covers were used, evaporated water was replaced each day. Duration of the test was 40 days. Blocks were treated by soaking followed by application of 200 psi liquid pressure. A 4 percent solution left 1 lb./cu.ft. dry chemical in the wood, while a 1 percent solution left about 0.25 lb./cu,ft. Preservatives used were l) cooperized chromated zinc chloride, 2) Wolman salts, and 3) Boliden salt. There were two replicates of each preservative concentration. Six of l) were attacked, the highest concentration being 0.46 pcf. Only one of 2) was attacked at 0.057 pcf and one of 3) at 0.061 pcf. In all cases, termite attack was on the springwood. Death of termites was a problem. During the first 14 days, vigorous termite activity took place but between the 14th and 20th day visible activity ceased in all jars containing blocks treated with 2) and 3).

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