The relationship between chromium fixation in CCA-C treated wood, as determined by CrVI analysis of solution expressed from treated wood and the leaching of Cu, Cr, As and CrVI in a simulated rain test are evaluated for dimension lumber (2"x6") and pole sections. Leachate concentrations after 2 hour exposure to a misting spray (about 300 mm cumulative rainfall) decrease rapidly with increased degree of fixation. For jack pine lumber, the concentration of contaminants in the leachate approaches the levels found in completely fixed material long before the chromium fixation is complete. Copper and arsenic levels in the leachate reach relatively low values at chromium fixation levels of 90% and higher and chromium levels at 95% and higher fixation levels. For red pine pole sections, the trend was similar except that higher levels of chromium fixation were required to minimize leaching rates. The results confirm that fixation procedures such as the chromotropic acid and other CrVI detection methods are conservative and following them guarantees that leaching losses are minimal.

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