A Multi-Analytical Diagnostic Study of Materials and Techniques for the Conservation of a Polychrome Wooden Sculpture by Neroccio di Bartolomeo de’ Landi

This study presents the technical–scientific investigation of a polychrome wooden sculpture attributed to Neroccio di Bartolomeo de’ Landi (1447–1500), a key figure in fifteenth-century Sienese art whose sculptural practice has remained analytically undocumented. The unpublished sculpture, likely representing Saint Ansanus and originally created in the 1470s, was historically reinterpreted as Saint Lazarus following its relocation to the former Hospital of San Lazzaro in Siena (Italy). A multi-analytical diagnostic campaign was undertaken to clarify its complex stratigraphy, guide conservation decisions, and reconstruct the artist’s original materials and techniques. The study integrated multispectral imaging, ATR-FTIR spectroscopy, portable ED-XRF, mechanical stratigraphic assays, and cross-section microscopy, enabling a comprehensive reconstruction of both the original polychromy and subsequent repainting campaigns. Results revealed area-specific original paint systems, including a possible organic red lake on an alumina substrate, stable copper-based blue paint layers, and a sophisticated flesh-tone stratigraphy combining cinnabar-modulated “imprimitura” layers with lead-white-based upper tones. The analytical evidence also documented the material traces of the sculpture’s iconographic recontextualization and its post-industrial interventions, firmly dated by the presence of titanium dioxide associated with an iron-based blue compatible with Prussian blue. The conservation treatment, informed by stratigraphic and analytical data, enabled the selective removal of non-original layers while preserving historically significant early reworkings. The findings provide the earliest material characterisation of Neroccio’s polychrome technique, offering new insight into his workshop practice and laying the foundation for future comparative studies across media. More broadly, the study contributes to the technical literature on Italian Renaissance polychrome sculpture and demonstrates the interpretive value of integrated scientific methods in reconstructing the cultural biography of multilayered devotional artefacts.