Wood color changes and termiticidal properties of teak heartwood extract used as a wood preservative

Abstract

Abstract The aim of this study was to evaluate the change in colorimetric patterns and the termite resistance of light-colored and low durability wood when impregnated with teak (Tectona grandis) heartwood extractives. Hot water and ethanol extracts were obtained from 20-year-old teak heartwood and used to evaluate the influence on color change and the natural resistance of 10-year-old teak sapwood and Pinus sp. For wood impregnation, a full-cell (Bethell) treatment was conducted. To verify the influence of the teak extracts, the colorimetric patterns of wood were determined using the Munsell and CIE-L*a*b* systems. Choice and no-choice feeding tests were performed under laboratory conditions to test the efficacy of the teak extract solutions against two termite species Nasutitermes corniger and Cryptotermes brevis. All of the extract solutions promoted a significant darkening of the wood, bringing the color of the impregnated wood closer to older teak heartwood than the untreated samples of the respective species. Ethanol extracts increased the resistance and mortality against N. corniger in both choice and no-choice tests. Resistance to C. brevis was not clearly affected.