Copper leaching from Kemwood ACQ and Embalit CBC treated wood products
P Esser, W L D Suitela, H Trompetter
TNO has performed a study on the leaching of copper from Kemwood ACQ and Embalit CBC treated wood products, further referred to as ACQ and CBC. The sawn dry wood has been impregnated using an industrial vacuum-pressure process with ACQ (with or without Ultrawood 4) or with CBC, under supervision of Flexchemie B.V. After treatment samples have been transported and subjected to leaching tests at TNO. The leaching tests applied were a submersion test according to NEN 7345 and shower tests according to a fixed protocol (Havermans et al., 1993). Parallel to each shower tests two or three screening tests for leaching have been performed, according to the existing guideline (BRL 0601, 1999) and according to experimental spray and submersion protocols. The screening should indicate, if the leaching limits of the guideline are likely to be met or not. The results of the screening leaching test have been plotted against the results of the shower tests. It has shown that the existing leaching limit for the "standard" guideline screening test of 0.5 mg copper per ml. is too low and does not indicate if the wood will perform well in the shower test, for both ACQ and CBC treated wood. The experimental spray test has shown to be fairly good as prediction for compliance in the shower test. Furthermore the submersion test according to NEN 7345 has shown promising reductions with a factor 3,7 of copper leaching in ACQ and Ultrawood 4 treated Norway spruce compared to an earlier test with ACQ treated Scots pine. The copper emission in CBC treated Scots pine was a factor 2,5 higher compared to the ACQ-Ultrawood 4 treated Norway spruce.