Colour Palette and Painting Technology of a Middle Byzantine Icon from Panagia Episkopi (Santorini, Greece): Evidence of Distinctive Painting Practices

The icon of the Virgin “Hodegetria” (or “Glykophilousa”) from the Church of Panagia Episkopi on Santorini (Thera) represents an important surviving example of Middle Byzantine panel painting in the Aegean. This study investigates its colour palette, painting technology, and chronology through optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), and radiocarbon dating of the wooden support. The analytical results identified vermilion/cinnabar, azurite, green earth, lead white, iron-rich ochres, and a carbon-based black pigment. Phosphorus detected in most paint layers is consistent with a possible proteinaceous binding medium, possibly egg tempera. The preparation layer consists mainly of gypsum, with phosphorus detected in some areas. Distinctive features were identified in the paint stratigraphy and pigment distribution. Homogeneous mixtures of pigments applied as single paint layers occur in three independent colour systems, while Christ’s red garment exhibits an unusual sequence of a thin hematite-rich layer over thicker vermilion/cinnabar. A later repainting of the Virgin’s tunic was identified through cadmium yellow and lithopone. Radiocarbon dating of the wooden support yielded a calibrated probability distribution centred on AD 1090 ± 60, providing an independent chronological framework for assessing the previously proposed art-historical dating.