The soil block and agar block test methods are used extensively as a screening process for potential and modified wood preservatives. The extent of decay in standard screening tests, indicative of preservative efficacy, is currently based on mass loss. Mass loss techniques, due to their limit of sensitivity in detecting significant mass loss vis-à-vis decay, require an extended fungus exposure period of the test specimens. Alternatively, an analysis of the effects of decay using mechanical loss test methods offer the possibility to significantly decrease the amount of time required to perform screening tests. Since a reduction in mechanical properties is continuous from the onset of decay, the exposure period of test specimens used in mechanical loss analysis is limited only by the sensitivity of the test apparatus to measure significant mechanical property loss. In the present study, the use of transverse compression, both radial and tangential, was evaluated as a method to quickly, and accurately, measure the extent of decay in thin yellow-poplar wafers exposed to a white-rot fungus in a soil block test. Within transverse compression, two properties of mechanical loss, compression strength at 5 % strain and modulus of elasticity to proportional limit were compared. While both methods of mechanical loss analysis proved to be a much quicker in determining significant decay than did mass loss, elastic loss appeared to offer a more accurate means of distinguishing the outset of significant decay than did strength loss.

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