“Idealità e Materialismo”: A first multi-technique characterization of Monteverde's plaster sculpture

Giulio Monteverde (1837–1917) was one of the major and most important sculptors of the early 1900s, both in Italy and at a worldwide level. Monteverde is mainly known for the artworks he realized in stone and metal, but he still remains almost unacknowledged for his plaster statues. Until today, neither the manufacture, nor the chemical composition of these sculptures was ever studied. In this paper, we have performed a preliminary investigation of the morphological and chemical composition of the gypsum plaster that Monteverde used to create his artwork in stone “Idealità e Materialismo”, today in the National Gallery of Modern Art in Rome. Micro-samples of the sculpture were characterized by scanning electron microscopy (SEM), analytical microprobe (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). This enabled the identification of both the chemical composition of the material used by the artist and the steps adopted to realize his sculptures. The analyzed samples have shown the presence of a thin finishing layer, as a “skin”, covering the whole artwork. This layer consists mainly of Gypsum, Calcite and Anhydrite and has, consequently, a different chemical composition than the inner bulk, which is made of pure gypsum. Such outer layer results in a marble-like surface of the sculpture with increased hardness and reduced porosity, which results in a higher resistance to external environmental conditions. This may also explain why Monteverde's plaster sculptures are so well preserved over time.