Radiata pine fretboard material of string instruments treated with furfuryl alcohol followed by tung oil

Abstract

Abstract The dimensional instability and inferior mechanical strength of radiata pine (Pinus radiata D. Don) limit its use in musical instruments. To improve its properties, a two-step treatment by furfuryl alcohol (FA) and tung oil (TO) were used involving impregnation of FA precursor solution into the wood matrix, forming a highly cross-linked resin, followed by a modification with TO. Examination using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed that FA resin was attached in cell walls and lumens, and the solidified TO in cell lumens and occluded pits. The incorporation of FA resin reduced the wood swelling coefficient by over 70% and the hydrophobic solidified TO decreased wood water uptake by over 80% enhancing wood dimensional stability. Although FA resin improved the modulus of elasticity and hardness of the wood, the modulus of rupture and impact bending strength were reduced. However, the additional TO impregnation step improved the modulus of rupture, impact bending strength, and wear resistance of the furfurylated wood. The performance of FA and TO treated radiata pine wood was better than that treated with FA or TO alone, and could meet the performance requirements of wood used for fretboard of string instruments.