Violin varnish induced changes in the vibro-mechanical properties of spruce and maple wood

Abstract

Violin varnishes are known to alter the longitudinal and radial material properties of violin tonewood. Here, the varnish-induced changes in the vibrational and elastic properties of spruce and maple wood were studied by modal analysis of rectangular plates. This contact-free investigation yields the eigenfrequencies and corresponding mode shapes and modal damping ratios of multiple out-of-plane modes. The longitudinal and radial E-modulus and the in-plane shear modulus were determined by an inverse material property determination process. The influence of traditional European varnish materials and different coating build-ups, comprising alcohol-based as well as oil-based varnishes, was studied during their application and for several months during drying and aging of the multi-layered systems. The evolutions of the changes induced by the different varnishes were rather similar and, except for modal damping, less pronounced for maple than for spruce. For the latter, the longitudinal E-modulus was slightly decreased while the shear modulus and radial E-modulus were increased after 18 months. The strong increases in modal damping ratios shortly after applying the coating systems (up to 150%) were reduced over time but remained significant for the time-span studied. However, also small differences between the influence of different coating systems and varnish materials on the amplitude of the induced changes became apparent.

Design of the Violin Performance Evaluation System Based on Mobile Terminal Technology

“…rough market research, we found that most of the musical instrument education software in the market focuses on providing learners with musical instrument teaching videos, or through the video function of mobile phones, real-time transmission of the fingering, and instrument pronunciation of the practitioners to the musical instrument teachers, so as to realize the accompaniment and remote guidance of musical instrument learning [3].…”

Analysis of the Anisotropy of Sound Propagation Velocity in Thin Wooden Plates Using Lamb Waves

“…Based on these considerations, currently, the most well-known types of varnishes used for maestro- and professional-level musical instruments are those with an oil-based solvent and those with an alcoholic solvent (spirit) [ 32 , 33 , 34 , 35 ]. Not only is the chemical composition of the surface treatment important but also the thickness of the varnish film and the varnish–wood interface, aspects highlighted in studies [ 36 , 37 , 38 ]. The type of varnish and its thickness correlated with the number of layers applied in the finishing process influence the tonality of the musical instrument as a result of not only the difference in stiffness between the wood and the varnish film but also as an effect of the increase in the mass of the layered material (wood–varnish) [ 31 , 32 , 38 ].…”

“…According to [ 36 , 38 ], to compare the mass changes of the spruce and maple boards before and after surface treatments (VS varnish system, UV exposure, and salt fog exposure), the changes were evaluated as area mass loading (AML) calculated based on mathematical relation (1): where is area mass loading induced by treatment (g·m −2 ); —the final mass of the treated wood; —the initial mass of the wooden sample; b —the width of the plate; and l —length of the plate [ 36 , 38 ].…”

Tunable Acoustic Properties Using Different Coating Systems on Resonance Spruce Wood

“…Thus, the research carried out by refs. [13][14][15][16] highlighted that both: the type of varnish (resin type) and especially the number of layers (film thickness) are responsible for the change in the acoustic quality of a violin, either ennobling or affecting the quality it had before being varnished. The argument of these researchers is related to the surface and mechanical changes that occur as a result of applying the varnish films, and on the other hand, the changes in the porosity and surface roughness of wood, as well as the increase in mass, stiffness and internal friction of the new system (varnish film and wood).…”