Diagnostic investigation to support the restoration of the polychrome terracotta relief "Madonna and Child" in Piove di Sacco (Padova, Italy).

• Polychrome terracotta relief with papier-mâché inserts from a shrine in Piove di Sacco (Padua, Northern Italy). • Non-invasive and microinvasive investigations performed before and during the restoration work. • Identification of the chemical composition of the pigments, fractures and internal damages, additions and retouchings, which strongly modified the original manufact. • Polychrome traces of blue of lapis lazuli highligh a valuable artwork. • Surprising resemblance with the style of Donatello and his apprentices. Restoration procedures of the polychrome terracotta relief " Madonna and Child " with papier-mâché inserts from a shrine in Piove di Sacco (Padova, orthern Italy) were assisted by analytical investigations, contributing to identify the chemical composition of the pigments, fractures and internal damages, additions and retouchings, which strongly modified the original manufact. In particular, energy dispersive X-ray fluorescence, Raman spectroscopy and FT-IR spectroscopy were employed to determine the chemical composition of pigments on the original layer and on the overpaintings and to understand the artistic techniques. Moreover, X-ray planar radiography and computed tomography were used to understand the structure and its conservative state. Finally, the relief, stylistically dated to the 17th century, turned out to be a Renaissance terracotta artefact. The polychrome blue traces of lapis lazuli highlighted a valuable artwork and the resemblance with the style of Donatello and his apprentices have recently led to further studies, as an initial part of a larger research on polychrome terracotta in Veneto. [Display omitted] [ABSTRACT FROM AUTHOR]