Detection of bronze paint degradation products in a contemporary artwork by combined non-invasive and micro-destructive approach

Conservation of contemporary art requires deep knowledge of techniques and materials used, in order to assess their decay rate and identify the proper way to preserve art objects; scientific investigations are thus fundamental for conservation purposes. This paper presents a multi-analytical approach based on the use of both non-invasive and micro-destructive techniques for the study of a contemporary artwork from the Italian artist Paola Levi-Montalcini. Object of this work is Nel Deserto, made in 1966 using several different modern materials. The mixed-media nature of the artwork required a complete characterization of the materials, preliminary to the challenging conservation intervention. Before the intervention, Nel Deserto was in fact showing severe signs of degradation, which prevented it from being exposed to the public. The analytical approach was based on the preliminary use of portable microscopy and XRF, followed by micro-FTIR on diamond cell and low-pressure SEM-EDS and allowed achieving fundamental information on the materials while not harming visibly the artwork. The interaction between a transparent film (made of a poly(vinyl chloride) copolymer) and a bronze-based paint, triggered untypical degradation phenomena. The loss of hydrochloric acid from the chlorine containing polymer led in fact to the formation of dark green colored copper halides, which irremediably altered the artwork.