P-056

Chiara Tuccio

chiara.tuccio@unipa.it

G. Montali, M. Pillitteri, R. C. Ponterio, D. Giuffrida, F. Armetta, M.L. Saladino

Università degli studi di Palermo, Italy

Non-invasive Spectroscopy for the Analysis of Pigment Traces

The study presented concerns the diagnostic investigation campaign conducted in situ on the archaeological remains of the Roman domus in Piazza della Vittoria, Palermo (Italy). The primary aim was to investigate the nature of the original pigments and any superimposed restoration substances. The analysis was performed on a variety of artefacts: 5 capitals, 3 fragments of column shafts, 2 fountains, and 8 wall portions. The diagnostic campaign combined non-invasive techniques including X-Ray Fluorescence (XRF), Raman spectroscopy, and Multispectral Imaging (VIS, IR, UV, VIL). XRF and Raman spectra were collected on the same representative areas to confirm pigment identification, while micro-samples were analysed in the laboratory through FTIR-ATR to investigate restoration materials and overlays. The combined spectroscopic approach enabled the characterization of the original colour palette, as well as the assessment of conservation issues. Identified pigments include: Egyptian blue, carbon black, green earth (celadonite), chromium green, yellow ochre, minium, and hematite. Spectral variations in red areas suggest differences in particle size and crystallinity of hematite, influencing the tone from red to violet. Multispectral imaging revealed further key insights. IR reflectography highlighted underlying compositional layers, such as red brushstrokes defining faux marble, applied after the yellow background, and the outlines of architectural elements like pilasters. VIL imaging showed extensive use of Egyptian blue on fountains and architectural fragments. UV-induced fluorescence imaging revealed residues of adhesives and gauze, likely related to past restoration attempts. Additionally, IR reflectography unveiled hidden graffiti, presumably from the 19th century, and grazing light imaging exposed fractures and surface discontinuities critical for conservation planning. This multidisciplinary and non-invasive methodology demonstrates the potential of spectroscopic techniques for pigment identification and the detection of hidden features, contributing both to the historical reconstruction and the preservation of archaeological surfaces.

Acknowledgments:This work has been funded by European Union (NextGeneration EU), through the MUR MUR-PNRR project SAMOTHRACE (ECS00000022).