Synchrotron radiation micro-CT for the investigation of finishing
treatments in ancient bowed stringed instruments:
issues and perspectives
Fiocco G. (a), Rovetta T. (a,b), Licchelli M. (a), Malagodi M. (a,c), Zanini F. (d), Lanzafame G. (d), Re A. (e,f),
Lo Giudice A. (e,f), Gulmini M.(g)
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(a) Laboratorio Arvedi di Diagnostica Non Invasiva, Università degli Studi di Pavia, Via Bell’Aspa 3, 26100 Cremona, Italy (b) Dipartimento di Fisica, Università degli Studi di Pavia, Via Bassi 6, 27100 Pavia, Italy
(c) Dipartimento di Musicologia e Beni Cuturali, Corso Garibaldi 178, 26100 Cremona, Italy (d) Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5, 34194 Basovizza, Trieste, Italy (e) Dipartimento di Fisica, Università di Torino, Via Pietro Giuria 1, 10125 Torino, Italy (f) INFN, Sezione di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
(g) Dipartimento di Chimica, Università di Torino, Via Pietro Giuria 5, 10125, Torino, Italy
giacomo.fiocco@unipv.it
Several materials have been used during the centuries by violin makers to treat and varnish the wood surfaces [1]. Recipes for the finishing materials were kept secret by the violin makers and traditional methods passed down from master craftsmen to apprentices. Information about lost procedures is crucial for supporting the conservation and the restoration of the valuable historical instruments, and it can be possibly recovered indirectly by scientific investigations. The scientist’s direct their focus toward facing difficulties related to the presence of multi-layered structures, where several inorganic and organic materials have been variously combined. Presently, the main methods to study such a complex stratigraphy requires samples to be detached from the artwork, following a micro-invasive procedure which is seldom allowed by the curators. Within this frame, the recovering of information by non-invasive procedures such as X-Ray computed tomography (CT) represents an extraordinary opportunity for scientists to reveal procedures and materials employed by the ancient masters.
In this research, the high spatial resolution and imaging properties of phase-contrast Synchrotron Radiation X-ray computed microtomography
(SR
μ
CT) have been employed on 1) a set ofmodel samples prepared in order to mimic the various situations that may be encountered when investigating finishing layers in ancient bowed string instruments and 2) a set of fragments detached from historical instruments during past restorations and selected from a
larger set on the basis of their chronological attribution (i.e. between 1650 and 1750).
The model samples have been prepared by spreading inorganic (silicates and sulphates) and organic (varnish coloured with a madder lake pigment) treatments on maple wood. They have been employed to optimize the instrumental settings and to guide the interpretation of the data obtained from the set of the historical fragments. These have been previously investigated by portable and bench-top analytical and morphological techniques (XRF, FTIR, SEM-EDX, Optical microscopy [2]).
SR
µ
CT volumes and images have been coupled with the information previously obtained on thehistorical fragments, allowing to identify how the main morphological and compositional properties of the finishing layers influence the 3D reconstructions and the 2D images.
References
[1] Echard J.P., Lavédrine B, Review on the characterization of ancient stringed musical instruments varnishes and implementation of an analytical strategy. Journal of Cultural Heritage, 9 (2008) 420-429 [2] Fiocco G., Rovetta T., Gulmini M., Piccirillo A., Licchelli M., Malagodi M., The art of violin making: rediscovering the “Cremonese” finishing treatments (17th-18th century) through non-invasive and micro-invasive techniques. Applied Spectroscopy, 71 (2017) 2477-2487.
Fiocco G. et al. X Congresso Nazionale AIAr
