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This study, in collaboration with the Arvedi Laboratory of Non-Invasive Diagnostics (University of Pavia) at the Museo del Violino of Cremona, aimed at developing a new hydrogel system for the cleaning of historical wooden surfaces, with a particular focus on string musical instruments. The cleaning of historical wooden instrument is traditionally performed using free water-based solvent, which are able to remove pollutants like dirt, soil and human sweat. However, due to the hydrophilic character of wooden surfaces, the loading of water should be localized in specific areas, avoiding excessive solvent leaching and the consequent damage risks. Konjac glucomannan (KGM), a biopolymer of natural origin, was chosen for our study because of its ability to absorb and retain significant amounts of water through its high content of hydroxyl groups. Hydrogel formulation as proposed in previous studies [1], consisting of KGM crosslinked with borax (sodium tetraborate decahydrate), was optimized, and an improved crosslinking method involving boric acid and sodium hydroxide (NaOH) was introduced, resulting in uniformly crosslinked gels with enhanced moisture retention and elasticity. KGM polymer matrix was also subsequently modified with natural polyphenols (PPs), in order to provide an alternative sustainable crosslinking option alongside the introduction of antioxidant properties and protection against UV radiation [2]. Three PPs have been selected to implement the modification: softwood kraft lignin (SKL), Vitis Vinifera tannin (Vv) and tannic acid (TA). PPs have additionally been functionalized with epichlorohydrin (ECH) to allow for a covalent bonding between the PP and KGM and to induce self-polymerization of the PP for reducing leaching especially of smaller PPs from the gel to the treated surface. Various analytical techniques were employed to characterize the starting PPs and their derivatives, and to analyze the morphology and moisture properties of the hydrogels comp

Over the last few decades, chemical and physical studies on bowed string musical instruments have provided a better understanding of their wooden finished surface. Nevertheless, until now only a few of them investigated the effects of the chemical pre-treatments in the traditional making procedures. Those treatments are believed to affect wood properties, its interaction with the following treatments (i.e. varnish application) and its vibro-mechanical behaviour (that may contribute to the acoustical properties of musical instruments). In this study, two traditional alkaline treatments were applied to reference samples of spruce wood, the wood commonly used to make violins’ soundboards. An integrated analytical strategy, which combines infrared spectroscopy, analytical pyrolysis coupled to gas chromatography-mass spectrometry, and gel permeation chromatography, was employed to investigate the chemical alterations of lignocellulosic polymers (cellulose, hemicellulose, and lignin). Results have shown that the selected alkaline treatments induce the partial hydrolysis of the hemicellulose chains and a slight decrease in the crystallinity of cellulose. We could also prove: (i) the cleavage of lignin-carbohydrate complexes formed by the covalent bonds between hemicellulose and lignin in spruce wood, and (ii) the partial breaking of the hydrogen bonds network in cellulose. According to the literature, the alteration of the lignin-carbohydrate complexes is responsible for changes in wood mechanical behaviour. Hence, future perspectives of this research could outline new knowledge on the vibro-mechanical behaviour of the violin soundboard and the consequent acoustics.

A multidisciplinary non-destructive study has been carried out on historical pipe organ fragments, trying to infer whether the spatial occurrence of different crystallographic phases (that is alpha‑tin, beta‑tin, cassiterite or romarchite) reflects the visible alterations patterns. We could indeed derive the presence of the beta‑tin phase. Several tin oxide phases have been detected too, associated with the visible occurrence of “grey regions” and hole borders (mapped by Raman spectroscopy), and hydrate phases (mapped by neutron imaging). We aim to demonstrate that neutron and Raman techniques can give relevant indications in archaeometallurgy studies of cultural heritage artifacts, where only non-destructive experiments can be performed. The combination of the two probes could be considered a protocol to be applied in the characterization of tin based specimens.