Search Results (2)

This study investigates the application of terahertz frequency-modulated continuous-wave (FMCW) imaging for the non-destructive inspection of a historical enamel plate, using both reflection and transmission modes. A 300 GHz FMCW radar system was employed to capture high-resolution images of the plate’s internal and surface structures. Through optimized data acquisition and processing, the system successfully revealed subsurface features such as fractures, as well as surface-level textural variations linked to the decorative glazes. Although pigment differentiation remains a challenge, contrast variations observed in THz images suggest correlations with material composition. The results highlight the potential of FMCW terahertz imaging as a compact, rapid, and non-contact diagnostic tool for cultural heritage analysis. Its practicality and adaptability make it particularly suitable for in situ inspections in museums or restoration contexts. Full article

This research aimed to characterise pigments used to decorate a polychrome earthenware bas-relief of the 15th century entitled “Madonna with Child, Saint Catherine of Siena, and a Carthusian Prior”, attributed to Giovanni Antonio Amadeo (Pavia, 1447–Milan, 1522) and owned by the Sforzesco Castle Museum of Milan. The artwork underwent a cleaning procedure whose aims were the removal of the dark coating that obscured its surface and restoration work that could bring back its original features. Before the cleaning, six microsamples were collected and analysed using optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDXS), and Fourier-transform infrared microspectroscopy in ATR mode (ATR-FTIR), providing the restorers with decisive information on the materials underlying the coating. After the cleaning, the terracotta appeared vibrantly coloured, mainly with bright red, blue, green, black, and white tones. Then, some in situ, non-destructive, spectroscopic measurements were performed by a portable Raman spectrometer on some of the areas that could not otherwise have been sampled. The analyses revealed the presence of natural pigments, including lead white, azurite, yellow ochre, carbon black, calcite, cinnabar, and gypsum. For Madonna’s mantle, cobalt and Prussian blue were employed. Furthermore, the presence of barium sulphate was widely evidenced on the bas-relief. Albeit cobalt blue is of synthetic origin, its presence is compatible with the 15th-century palette, whereas Prussian blue and barium sulphate could be imputed to a previous restoration. Finally, the use of true gold for the background of the earthenware attests to the artwork’s importance and value. Full article