EVALUATION OF BORIC ACID/VEGETABLE OIL COMBINATIONS FOR WOOD BIOLOGICAL RESISTANCE AND REDUCTION OF BORON LEACHING

Florent LYON
PhD student-Laboratory of mechanics and civil engineering-University of Montpellier II
Adress: CC 048 Place Eugene Bataillon, 34095 Montpellier Cedex 5, France.
Tel : 0033 (0) 467149344. Fax : 0033 (0) 467144792. E_mail: lyon@lmgc.univ-montp2.fr

Marie France THEVENON
PhD.-CIRAD PERSYST - UPR 40. Laboratoire de préservation des bois
Adress: TA B-40/16. 73, rue Jean Francois Breton. 34398 Montpellier Cedex 5 - France.
Tel : 0033 (0) 467616523. Fax : 0033 (0) 467616560. E_mail: marie-france.thevenon@cirad.fr

Won Joung HWANG
PhD student-Research Institute of Sustainable Humanosphere, Kyoto University
Adress: Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Tel : 0081 774383673. Fax : 0081 774383600. E _mail: wjhwang@rish.kyoto-u.ac.jp

Yuji IMAMURA
Prof. PhD.-Research Institute of Sustainable Humanosphere, Kyoto University
Adress: Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Tel : 0081 774383673. Fax : 0081 774383600. E _mail: imamura@rish.kyoto-u.ac.jp

Joseph GRIL
Prof. PhD.-Laboratory of mechanics and civil engineering-University of Montpellier II
Adress: CC 048 Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
Tel : 0033 (0) 467143433. Fax : 0033 (0) 467144792 E_mail: jgril@lmgc.univ-montp2.fr

Antonio PIZZI
Prof. PhD.-ENSTIB-LERMAB, UMR 1093 UHP/ENGREF/INRA. University of Nancy 1
Adress: 27 Rue du Merle Blanc, BP 1041. 88051 EPINAL Cedex 9, France.
Tel : 0033 (0) 329296117. Fax : 0033 (0) 329296138. E_mail: pizzi@enstib.uhp-nancy.fr

Abstract: In the light of European directive (98/8/CE) on efficacy and toxicity of biocides coming into force on 2008, wood preservation research is now focussing on environmentally-friendly wood preservatives.
Boron-based preservatives are considered as a good alternative regarding their low mammalian toxicity and their broad spectrum effectiveness against wood degrading organisms like fungi and termites.
Nevertheless, their high solubility into water is accelerating their leaching out of wood under outdoor exposition.
Combinations of vegetable oil and borates have been tested as wood preservatives. Three vegetable oils varying by the permeability of their dry film are evaluated for boron retention and biological resistance to termites and decay fungi.
It appears that vegetable oils provide boron retention of about 30% of initial amount depending on oil drying properties. Linseed oil is the most efficient, followed by soybean oil and rapeseed oil.
Durability of C.japonica sapwood specimens has been enhanced by application of linseed oil alone but not enough to reduce termite's attack of Coptotermes formosanus.
Treating wood with a 1.0% w/w boric acid solution prior to oil treatment protects C. japonica from termite and fungi degradations.
Efficiency against termites is mainly due to boron retention but hydrophobic oil also forms a barrier decreasing fungi penetration.

Key words: boric acid, vegetable oil, wood preservation, termite test, fungi test.

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