Analisi su vernici e resine di strumenti musicali antichi: i mandolini Vinaccia (1769-1787)

This work aimed to characterize coatings on the surface of mandolins produced in Naples by the Vinaccia family since 1769 to 1785. These instruments are currently stored in the Museum of Musical Instruments in Rome. The analysis of micro-samples taken from instruments lead to identify the materials and it represents an important contribution to the study of this class of instruments. Varnish samples were taken from the surfaces and analyzed by SEM-EDS, micro-FT-IR, and micro-Raman techniques. Infrared spectra, registered in ATR mode, suggest shellac as a organic component of the sound board decoration. The presence of protein compounds, possibly animal glue, and oils is also observed in some samples. SEM-EDS investigations detected iron in some part of the sound board decoration, suggesting that an inorganic pigment (e.g. hematite) was mixed with the shellac medium. Micro-RAMAN analysis confirmed the presence of hematite. In addition, feldspar grains (more or less 10 microns) have been also identified by SEM-EDS in some varnishes of the mandolins. Coal fragments and diatom microfossils were found inside the resin of the sound board decoration.