Comparison of laboratory and natural exposure leaching of copper from wood treated with three wood preservatives

IRG/WP 08-50258

P A Cooper, Y T Ung

Standard and non-standard laboratory and field leaching tests were used to compare copper leaching from wood treated to above ground and ground contact specified retentions for three wood preservative systems, CCA-C, ACQ-D and a micronized copper formulation with quat DDAC as co-biocide. Copper leaching was highest for the ACQ formulation. Percent leaching was lowest for the micronized copper system (MCQ) but amount of copper leached (mg/m2) was higher for MCQ than for CCA because of the higher copper content in the former formulation. The amounts of copper leaching varied considerably from test to test, but in most cases, the relative amounts of copper leaching from wood treated with the three formulations were consistent. One exception was the AWPA E20 soil leaching test which provided variable results, that showed that leaching of copper from CCA and MCQ samples was more similar to that from ACQ samples than observed for the other test methods. Also, the natural exposure tests (horizontal and vertical exposure) has less dramatic differences among the preservative systems.

Keywords: copper, leaching, preservatives, alkaline copper Quat (ACQ), Chromated Copper Arsenate (CCA-C), Micronized Copper Quat (MCQ), laboratory testing, natural exposure, southern pine

Conference: 08-11-30/12-02 Flamingo Beach, Costa Rica

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