Chemometric tools to investigate complex synchrotron radiation FTIR micro-spectra: focus on historical bowed musical instruments


  • Giacomo Fiocco
  • Silvia Grassi
  • Claudia Invernizzi
  • Tommaso Rovetta
  • Michela Albano
  • Patrizia Davit
  • Monica Gulmini Dipartimento di Chimica - Università di Torino
  • Chiaramaria Stani
  • Lisa Vaccari
  • Maurizio Licchelli
  • Marco Malagodi



The investigation of the coating systems used on historical bowed string musical instruments is generally highly complex due to the coatings’ reduced thickness and multi-layered structure. Furthermore, sampling is rarely feasible, and non-invasive approaches do not always allow researchers to undertake a thorough characterisation. Thus, in the rare cases of availability, the opportunity must be taken to investigate the best micro-samples in detail using a suite of analytical spectroscopic techniques that allow for obtaining various informative spectra. Their subsequent interpretation should lead to the characterisation of the finishing layers, the preparation of which involves a careful selection of organic and inorganic compounds.

In the present work, synchrotron radiation and micro-Fourier-transform infrared spectroscopy were combined in terms of reflection geometry and chemometrics to investigate six cross-sectioned micro-samples detached from four bowed string instruments produced by Antonio Stradivari, Francesco Ruggeri, and Lorenzo Storioni. Various chemometric tools enabled us to perform a preliminary exploration of the entire collected infrared dataset, while a classification model based on partial least squares–discriminant analysis was used to discriminate the materials through the characteristic signals. High model specificity (> 0.9) was achieved in the prediction, providing the groundwork for the application of a fast and rigorous methodological approach.






Research Papers