Weathering of treated wood directly after impregnation leaches up to 2% of copper-chromate-containing wood preservatives. Almost total fixation of Cr+6 is achieved by steaming the treated wood at 100°C to 120°C, preferably 110°C. To initiate such spontaneous fixation 85°C to 90°C inside the wood are essential, which requires heating times ranging from 20 to 80 min, depending on timber species, retention, required depth of fixation, and steaming conditions. Lower temperatures without steam cause an increased leaching, due to drying effect without promotion of fixation. For softwoods the efficacy of the preservative is not effected; in the case of hardwoods treated with CCA, a certain reduction against softrot fungi was noticed. Both bending and compression strength of pine and spruce remained unchanged. A carefully performed steam fixation will effectively reduce pollution.

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