The most important disadvantige of copper based preservatives is low copper fixation on wood components. This is an important drawback, when impregnated wood is used in conditions where leaching of active components is possible. Copper fixation used to be improved with addition of chromium compounds. Due to chromium health and environmental issues, intense researches on environmentally more friendly preservatives are going on. Combinations of ethanolamine and octanoic acid were found as suitable chromium substitutes. It has already been proven that ethanolamine reacts with wood and copper, resulting in improved Cu fixation. On the other hand, octanoic acid has hydrophobic mode of action. Therefore, the influence of concentration of newly developed preservative solutions, method of treatment and wood species on copper leaching were examined. To elucidate those questions, specimens made of spruce, pine and beech were impregnated with different aqueous solutions on the basis of copper, ethanolamine. octanoic acid, quaternary ammonium compounds and boron. Specimens were treated using 3 different procedures: brushing, dipping and vacuum treatment. Leaching was performed according to modified standard procedure SIST EN 1250/2. In comparison to the specimens impregnated with the solution of the higher concentration less copper was leached from the ones impregnated with a lower concentration of preservative solution. On the average, the lowest percentage of Cu was leached from spruce specimens treated with aqueous solution of copper, ethanolamine and octanoic acid. Brushing of the specimens resulted in the highest leaching.
|
