Accelerated fixation of CCA-treated poles

The effects of temperature and wood species on the rates of fixation of CCA-C treated pole sections are evaluated by a number of methods: 1) qualitative hexavalent chromium (CrVI) color reaction with chromotropic acid, 2) quantitative analysis of CrVI in expressed solution; 3) total Cr, Cu, and As in expressed solution; 4) pH of expressate; and 5) pole surface leaching characteristics. There are generally good correlations among the methods. Qualitative detection of CrVI, or qualitative analysis of CrVI, or total Cr are the best indicators of fixation since both copper and arsenic are immobilized in wood before all of the CrVI is reduced. Fixation time can be greatly reduced by exposing poles to elevated temperatures at near saturated humidity conditions. Species that require about 14 days to fix completely at 20?C can be fixed in 8 to 10 hours at 70?C. There are definite differences in the rates of fixation of different pole species, with western redcedar requiring significantly longer to fix than Douglas-fir, red pine, jack pine, lodgepole pine, and southern yellow pine.

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