Full-scale impregnation of wood with siloxane was carried out using supercritical carbon dioxide as solvent. A batch of 3530 kg of Scots pine sapwood was impregnated to a retention of approximately 1.3% siloxane. The treatment also consisted of a simultaneous impregnation with organic biocides. The performance of the wood was evaluated in terms of capillary water uptake according to a modified EN 15148 and compared to previous pilot-scale impregnation trials. The performance results showed a good correlation between results obtained in pilot-scale and full-scale tests. The results show that full scale supercritical impregnation of pine sapwood with siloxane is possible and that a significant improvement in the water repellency and durability of the sapwood can be gained from the treatment. The treated wood had a capillary water absorption coefficient (WAC) of 0.74 compared to 2.35 for non-treated samples. This corresponds to 10-fold decrease in the rate of capillary water absorption.

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