Insight on the deterioration of cultural objects: a multi-analytical approach to characterize degradation products of lead weights from a Steinway & sons piano

The identification of the degradation products in objects of cultural significance, including musical instruments (e.g., a piano), is a key issue for the preservation and valorisation processes of cultural heritage. The aim of this study is to characterize the degradation products of lead weights from an important Steinway & sons piano using a multi-analytical approach that includes ionic chromatography (IC), X-ray diffraction (XRD) and Fourier transform-infrared (FTIR) spectroscopy analyses. These techniques allowed us to identify hydrocerussite as the main degradation product on the superficial layer of lead weights, followed by lead acetate and formate. Moreover, accelerated corrosion experiments in closed environments were performed under acetic and formic acid atmospheres to evaluate the development of lead acetate and formate over time. Exposure of lead weights to formic and acetic acid vapours leads to the prevalent formation of basic lead formate, which promotes the formation of hydrocerussite. These results can help to limit the degradation of these piano components and consequently preserve the sound of the piano itself.