Stratigraphic analysis of historical wooden samples from ancient bowed string instruments by laser induced breakdown spectroscopy

One of the most hotly debated subjects in lutherie circles is the composition of the finishing layers applied by the violinmakers of the past on their valuable bowed string instruments. These are often composed of several organic and inorganic materials, variously mixed and overlaid. During the last decade many analytical strategies were put in place in order to correctly identify these materials. The most used are surely non- and micro-invasive spectroscopic techniques (e.g. XRF, EDX, FTIR) integrated, when possible, with the imaging and tomographic ones with a multi-analytical approach. In this work, Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT) were tested together on laboratory mockups and historical bowed string instruments in order to identify and characterize the materials composing the finishing layers of these selected artworks.