“Like many discoveries, this one could have been accidental. Perhaps the violin makers were not even aware of the acoustical effects of the chemicals. Both Stradivari and Guarneri wanted to treat their violins to prevent worms from eating away the wood. They used some chemical agents to protect the wood from worm infestations of the time, and the unintended consequence from these chemicals was a sound like none other,” he adds.
The team tested several instruments, including violins and cellos, produced by Stradivari and Guarneri from 1717 to around 1741, using spectra analysis and other methods.
The results and those previously reported by Nagyvary showed that two specific areas of the instruments accounted for their unique sound – chemicals used in the varnish and fillers of the instruments, and the overall wood treatment process used by Stradivari and Guarneri.
This sounds rather appealing (heh), though certainly there will be critiques of it. The blurb there doesn't say how many other instruments were also tested, how the particular effects of the chemicals are thought to affect the sound, etc.