Chemical distinctions between Stradivari's maple and modern tonewood

Violins made by Antonio Stradivari are renowned for having been the preferred instruments of many leading violinists for over two centuries. There have been long-standing questions about whether wood used by Stradivari possessed unique properties compared with modern tonewood for violin making. Analyses of maple samples removed from four Stradivari and a Guarneri instrument revealed highly distinct organic and inorganic compositions compared with modern maples. By solid-state ¹³C NMR spectroscopy, we observed that about one-third of hemicellulose had decomposed after three centuries, accompanied by signs of lignin oxidation. No apparent changes in cellulose were detected by NMR and synchrotron X-ray diffraction. By thermogravimetric analysis, historical maples exhibited reduced equilibrium moisture content. In differential scanning calorimetry measurements, only maples from Stradivari violins, but not his cellos, exhibited unusual thermooxidation patterns distinct from natural wood. Elemental analyses by inductively coupled plasma mass spectrometry suggested that Stradivari's maples were treated with complex mineral preservatives containing Al, Ca, Cu, Na, K, and Zn. This type of chemical seasoning was an unusual practice, unknown to later generations of violin makers. In their current state, maples in Stradivari violins have very different chemical properties compared with their modern counterparts, likely due to the combined effects of aging, chemical treatments, and vibrations. These findings may inspire further chemical experimentation with tonewood processing for instrument making in the 21st century.