Giovanni Santi's Late 15th-Century Paintings: Microscopic, Spectroscopic and Chromatographic Investigations on Pigments, Powdered Glass and Binding Media

After a huge non-invasive diagnostic campaign performed on the corpus of Giovanni Santi's artworks, three paintings were selected and investigated: the Martyrdom of Saint Sebastian panel, the Visitation altarpiece and the canvas with Tobias and the Archangel Raphael (c. 1487 and 1494). Micro-invasive investigations including optical microscopy, ESEM-EDX, micro-Raman spectroscopy, FTIR and FTIR-ATR spectroscopy and GC-MS were carried out on selected micro samples. The results of the integrated analyses confirmed the use of a Renaissance palette with oil and, only in a few cases, tempera techniques. Some significant peculiarities emerged in Santi's practice, as he used localized off-white priming and colorless powdered glass with a siccative oil--in red, flesh, pinkish and green hues--confirming the influence of the Flemish painters in Urbino and, possibly, also in western central Italy. This innovative technical expedient compared to the traditional Italian painting technique was identified also in red and bluish samples collected from the Communion of the Apostles panel painted by Justus of Ghent around 1473-1474 for Urbino Corpus Domini Confraternity. The Flemish master was called to the court of Duke Federico to paint in oil and his presence at the 'Urbino workshop' probably contributed to the diffusion of this technique. Both in Giovanni Santi's paintings and the Communion of the Apostles, the glass particles are related to a soda-lime glass typical of the Italian area, widely detected in Italian paintings from the late 15th and 16th centuries.