3D virtual slicing of an antique violin reveals ancient varnishing methods (Vol. 50, No. 2)
Physicists and chemists use 3D scanning to unlock the forgotten secrets of the multi-layered coating methods that give violins their exceptional tone and look.
Italian violin-making masters of the distant past developed varnishing techniques that lent their instruments both an excellent musical tone and impressive appearance. Few records from this era have survived, as techniques were most often passed down orally to apprentices; only scarce information is available on the original methods used for finishing the instruments. In a new study published recently, the authors use the Elettra synchrotron facility in Trieste to develop a non-invasive 3D-scanning approach, using the Synchrotron Radiation micro-Computed Tomography (SR-micro-CT), that yields insights into the main morphological features of the overlapping finishing layers used on violins. In turn, the morphological images can be used to determine the chemical nature of the coating. This newly developed method could help scientists rediscover the procedures and materials used, and reproduce the multi-layered coating methods of the ancient masters.
They first use the X-ray beam to scan two sets of mock-ups, prepared in their lab to mimic the finishing layers on the historical instruments. Using the mock-ups, they then optimise the 3D scanning settings, boost the spatial resolution and define the parameters required for 3D reconstruction. They then focus on a large fragment removed from a damaged cello made by the 17th-century Italian luthier Andrea Guarneri. Lastly, they compare their findings with those produced by micro-invasive analyses of the varnish to evaluate the merits of the reconstructed volumes and virtual slicing in terms of investigating such layered, complex structures.
G. Fiocco, T. Rovetta, M. Malagodi, M. Licchelli, M. Gulmini, G. Lanzafame, F. Zanini, A. Lo Giudice, and A. Re, Synchrotron radiation micro-computed tomography for the investigation of finishing treatments in historical bowed string instruments: issues and perspectives, Eur. Phys. J. Plus 133, 525 (2018)