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Bi-oleothermal treatment of wood at atmospheric pressure : biological properties, weatherability and coatability

Podgorski L., Le Bayon I., Paulmier I., Lanvin J.D., Grenier D., Baillères H., Méot J.M.. 2007. In : 3rd European Conference on Wood Modification, 15-16 October 2007, Cardiff, United Kingdom. s.l. : s.n., 10 p.. European Conference on Wood Modification. 3, 2007-10-15/2007-10-16, Cardiff (Royaume-Uni).

Bi-oleothermal© process is a simple treatment which operates at atmospheric pressure and allows a deep impregnation of wood with hydrophobic products using cheap facilities. The process includes two stages. The first one is a dipping of wood samples in a hot oil bath (between 110°C and 200°C). At the end of the first stage the wood contains a significant volume of vapour. The second one is a dipping in an oil bath but at a lower temperature (20°C to 80°C). In this second bath samples cooling leads to water condensation. A vacuum is created inside the samples and makes the oil to impregnate the wood. In this study, this process has been used to impregnate several wood species with different linseed oil compounds with and without addition of biocides. The resistance to wood destroying fungi has been assessed using a method adapted from EN 113. Results show that the linseed oil compounds lead to an increase in the natural durability. The resistance to termites and to house longhorn beetles has been assessed using EN 117 and EN 47 respectively. Wood treated with biocide-free oil is attacked by termites but afterwards the oil induces the death of the insects. The addition of biocide makes the wood completely protected from termites attacks. EN 47 results show that 83% of mortality amongst the beetles is obtained with the biocide-free oil and 100% with the oil including biocide. The resistance of the treatment to weather has been studied using artificial weathering test according to EN 927-6. Results show that the coating provided by this process constitutes a low performing product compared to conventional stains. However the compatibility with a solventborne or a waterborne stain is ensured and leads to good performances after artificial weathering.

Mots-clés : bois; traitement thermique; immersion; pression atmosphérique; huile végétale; lutte anti-insecte; préservation du bois; agent de conservation

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