Fixation and leaching characteristics of Douglas-fir treated with CCA-C

Abstract

Fixation and leaching characteristics of chromated copper arsenate (CCA)-treated Douglas-fir sapwood and heartwood were evaluated using the expressate method and the American Wood Protection Association (AWPA) E11-97 leaching procedure. CCA fixation, monitored by hexavalent chromium reduction, was much faster in heartwood than in sapwood; copper and arsenic fixation in heartwood appeared to be incomplete, regardless of the duration of the fixation time. Poor fixation of copper and arsenic in heartwood was confirmed using leaching tests. Based on the results, we conclude that CCA is not an appropriate preservative for Douglas-fir heartwood because of its poor fixation quality. Therefore, the use of CCA-treated Douglas-fir products in environmentally sensitive areas should be restricted or banned.