The identity of Stradivari violin ex-San Lorenzo: is it still preserved?

Historical musical instruments, especially violins, are witnesses of centuries-old stories and events, passing from hand to hand among musicians, collectors and restorers. Historical last wills as well as trading documents allowed to reconstruct the movements around the world of the decorated ex-San Lorenzo violin and its story throughout its owners. The history of this precious violin started in 1718 in the Cremonese Stradivari’s workshop; it represents the ultimate development of the Master’s “golden age period” (1700 to 1720) and a unique example for the emblematic inscription “GLORIA ET DIVITIAE IN DOMO EIUS” adorning the centre ribs [1]. The ex-San Lorenzo violin was property of the virtuoso Mauro D’Alay (1687-1757) and then of the violinist G.B. Viotti (1755-1824), before being sold to the Duke of San Lorenzo, from whom the musical instrument took the name [2]. Several non-invasive imaging (endoscopy, stereomicroscopy SM, VIS and UVIFL photography, X-ray radiography RX, XRF mapping) and spectroscopic techniques (FORS, FTIR in reflectance mode, FTIR, Raman, XRF) were used in order to: (i) evaluate the preservation status of the violin, (ii) characterize the likely original materials such as those composing the varnishes and the wood treatments, (iii) identify restoration compounds. From the multi-analytical approach, the reconstruction of the original stratigraphy appeared to be limited to the top plate of the violin, where a proteinaceous filler and an aged siccative oil- and terpenic resin-based varnish were identified. Additionally, recently-laid waxes and possible benzoin resin were detected in few areas. The back plate as well as the ribs and the scroll, instead, underwent large restoration and maintenance treatments: the surface, in fact, is mostly covered by a polysiloxane material (e.g. silicone oil) often found together with shellac resin, both commonly used modern polishes in the musical instrument field. Signals of Fe and Mn, probably associated to red earth pigments, were investigated on the whole instrument [3]. Interestingly, traces of Br can be ascribed to bromomethane for woodworm fumigations in the last century. These results, mostly related to non-documented restoration processes, should be considered a valid starting point to open the debate about what should be preserved of a musical instrument and how to perform i