The influence of CCA penetration in sawnwood on its performance against decay fungi

The objective of the study was to compare the relative performance of lumber treated with chromated-copper-arsenate (CCA) to two standards used by industry. The two standards were the Canadian Standards Association (CSA) wood preservation standard for lumber used out of ground contact, and the industrial standard PS-1 proposed by the Canadian Institute of Treated Wood (CITW). Hem-fir and lodgepole pine lumber, treated to the CSA and PS-1 standards, was obtained from commercially available material. The chosen boards were analyzed and those found to conform to the minimum CCA penetrations and retentions for each standard were processed for use in the investigation. Each board was cut into 50-cm-long sections, conditioned by an alternating heating and wetting regime for 10 days to induce the formation of checks, and cored to produce the test samples. The discs produced from the lumber were further processed by drilling a “well” in each so that the thickness of treated wood tested was exactly 5 mm (PS-1) and 10 mm (CSA). The discs were sealed in a vinyl cylinder and exposed to three decay fungi (Postia placenta, Gloeophyllum trabeum, and Coniophora puteana). Following completion of the decay exposure, the discs were visually and microscopically examined for decay. The results showed that the two standards provided equivalent protection in this accelerated test.

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