93 WOOD RESEARCH 55 (1): 2010 93-100 INFLUENCE OF MONTAN WAX EMULSIONS ON LEACHING DYNAMICS OF BORIC ACID FROM IMPREGNATED WOOD Boštjan Lesar, Miha Humar University of Ljubljana, Biotechnical Faculty, Department of Wood Science and Technology, Ljubljana, Slovenia Polonca Kralj University of Ljubljana, Faculty of Chemistry and Chemical Technology, Department of Analytical Chemistry, Ljubljana, Slovenia ABSTRACT Boron biocides are one of the most frequently used components of commercial wood preservatives. Tey are very efective fungicides and insecticides, but they do not react with wood and thus leach from it in wet applications. In order to reduce leaching of boric acid, montan wax emulsion was introduced to the preservative solution. Spruce wood specimens were vacuum impregnated and afterwards leached according to the novel OECD and prCEN/TS 15119-1 procedures. Tose two methods are non-continuous and are used for estimations of boron leaching from use class II and III applications. Te results showed that addition of LGE emulsion does not reduce boron leaching signifcantly. Despite of the fact that both methods applied are non-continuous, it can be evident, that OECD procedure is much more severe than prCEN/TS 15119-1 one. KEY WORDS: boric acid, leaching, montan wax emulsion, Norway spruce, wood preservation INTRODUCTION Boron based compounds are one of the most important classical biocides, that remained on the market even after implementation of European Biocidal Product Directive (BPD 98/8/ EC, 1998). Due to their broad spectrum of fungicidal and insecticidal properties, borates are considered more efective preservatives than copper and zinc ones, with the later two performing better only because of their f xation in wood, not their inherent fungicidal activity (Obanda et al. 2008). To inhibit growth of the fungi growing on nutrient medium, between 200 and 400 ppm of boron is necessary. In contrary, to inhibit growth of copper sensitive species 650 ppm and to inhibit growth of copper tolerant up to 1500 ppm of copper is required (Lesar and Humar 2009). Use of borates is limited due to their high mobility and good water solubility what results in