CT Scans Illuminate Wood Density Characteristics
In 2008, Berend Stoel of Leiden University Medical Center in the Netherlands collaborated with luthier Terry Borman to perform CT scans on several Stradivari violins alongside modern instruments for comparison. The primary goal was to analyze the density of the woods used because variations in wood density influence vibrational efficiency and sound production. Stoel, who originally designed a computer program to noninvasively calculate lung densities in emphysema patients, adapted this technology to assess wood densities derived from CT scan data.
The study revealed no significant differences in average wood density between classical Stradivari violins and contemporary instruments. However, the critical finding was that the divergence in density between early-growth and late-growth wood grains was markedly smaller in the Cremonese violins compared to modern violins. The researchers concluded, “Our results clearly document basic material property differences between the woods used by the classical Cremonese and contemporary makers.”
Role of Varnish in Acoustic Enhancement
Further evidence supporting the influence of varnish on sound quality emerged from a 2016 study conducted by the Swiss Federal Laboratories for Materials Science and Technology (EMPA). The research focused on how varnish chemical composition, thickness, and penetration depth into the wood affected acoustic characteristics.
The EMPA team used samples from a single Norway spruce tree, treated with various varnishes—two experimental formulas and two varnishes favored by German master violin makers. Over time, they carried out vibration tests combined with x-ray tomography to evaluate acoustic impact.
Results indicated that all varnishes increased the wood’s damping ability, which refers to its capacity to absorb and diminish vibrations. This increase in damping compared to untreated wood produced a warmer, mellower, and more aesthetically pleasing sound. The varnishes preferred by German luthiers demonstrated a slight advantage, also enhancing sound radiation, leading to louder tones.
Chemical Treatment Evidence from Taiwanese Research
A 2017 analysis by Taiwanese scientists compared maple wood used by Stradivari with contemporary high-quality maple sources. Their chemical analysis detected treatments including elements such as aluminum, calcium, and copper. Additionally, degradation over time of the hemicellulose component in the wood resulted in the Stradivari and Guarneri violins studied holding approximately 25% less water than modern instruments.
According to Nagyvary, quoted in The New York Times, “This is fundamentally important because the less moisture, the more brilliant the sound.” This moisture reduction contributes significantly to the distinctive and superior tonal qualities of the historic instruments.
— The Violin Post Editorial Staff
