Copper-ethanolamine based wood preservatives are replacing several classical copper-chromium based solutions, due to foreseen ban of chromium. Fixation of copper-ethanolamine based wood preservatives is not as good as fixation of copper-chromium ones. The main object of this manuscript was to prove, that ethanolamine is the prime reason for insufficient fixation of copper-ethanolamine formulations. Ethanolamine causes depolymerization of lignin, what consequences in increased leaching. In order to prove that presumption, Norway spruce (Picea abies) and Beech (Fagus sylvatica) wood specimens were impregnated with three different aqueous solutions consisting of copper-ethanolamine and additives/co-biocides of three different concentrations. After four weeks of fixation, those specimens were leached for seven days. Mass change after leaching was measured gravimetrically. Modulus of elasticity (MoE) was determined using non-destructive technique. In parallel, copper, nitrogen and carbon contents were analysed in leachates and carbon and nitrogen content were measured in leached and un-leached wood blocks as well. The results showed that presence of ethanolamine in preservative solutions caused MoE change. In leachates significantly increased carbon as well as copper contents was determined. There was good correlation between organic carbon in leachates and copper leaching. The main source of organic carbon was wood components. Therefore, we believe, that our hypothesis of ethanolamine induced lignin depolymerization is confirmed.

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