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International audience; The health problems amongst musical instrument makers working on the White mulberry (Morus alba), lead to investigate the toxicity potential of wood extractives. Five solvents of different polarity and two methods of extractions were used to ensure a thorough, clear and classified compound removal. The compounds were identified using qualitative GC-mass and the toxicity were determined by studying their effect on termite survival (Reticulitermes flavipes). The results indicated the presence of different compound categories like phenols, higher hydrocarbons, fatty acids, sterols and aromatic components in the extractives. These compounds were not removable by just one solvent and the order of removal was polarity related. The extractives were found toxic towards termites. Resorcinol, which corresponded to the highest proportion of peaks in the GC-mass spectra, has been assigned as the possible compound responsible for the allergic reactions by the artisans.

Vibrational properties of wood are affected by several parameters, of which extractives can be one of the most important ones. Wood for European musical instruments has been often studied, but traditional Middle Eastern ones had been left unnoticed. In this study white mulberry (Morus alba L.), the main material for long-necked lutes in Iran, was extracted by five solvents of various polarities (water included). Free-free bar forced vibrations were used to measure longitudinal (L) loss tangent (tanδ), storage (elastic) modulus (E′) and specific modulus (E′/γ) in the acoustic range. Their anisotropy between the 3 axes of orthotropy was determined by dynamic mechanical analysis. Native wood had a quite low E L′/γ but its tanδ was smaller than expected, and the anisotropy of tanδ and E′/γ was very low. Removal of extractives caused tanδ to increase and moduli to decrease. Acetone, the most effective solvent on damping despite a moderate extraction yield, increased tanδ L by at least 20% but did not modify E′/γ as much. When used successively, its effects masked those of solvents used afterwards. Anisotropy of E′/γ was nearly unchanged after extraction in methanol or hot water, while tanδ was much more increased in R than in T direction. Results suggest that in white mulberry, damping is governed more by nature and localization of extractives rather than by their crud abundance.

Mulberry wood (Morus alba L.) is traditionally used in Iran to manufacture music instruments such as tar and setar. But little is know and contradictory statements are found on the natural durability of Morus alba. Moreover, in many cases, Iranian instrument makers leave freshly cut Mulberry timber into water (cold or hot) for a time period depending on the craftsman habit, without any real knowledge or rationalization of the process. It is believed that this step induces a better acoustic behaviour of the wood. It also has to be underline that the leaching waters are very aggressive and contribute to severe skin disorders amongst the wood workers. In this study, the natural durability of leached (according to EN84) and un-leached Morus alba was evaluated against both fungi and termites. The fungal tests followed the guidelines of XP Cen/TS 15083-1, and the wood was exposed to temperate and tropical fungal strains. The termite tests were performed according to EN 117 and the mass loss of the samples was measured along with the visual rating. As a second step, wood powder was extracted using different solvents (including water) and preliminary tests on the activity of these extracts on termites were conducted. The chemical analysis of these extractives is still on going.