Characterising the unique polychrome sinopia under the Lod Mosaic, Israel : pigments and painting technique

A sinopia, usually a monochrome preparatory drawing made on a mortar substrate, was used in the Graeco-Roman world either as a base for frescoes or to facilitate the application of coloured mosaic tesserae on walls or floors. In 2009, during the detachment of the Lod Mosaic (Israel), an unexpected and, for the Classical Roman era, a unique, polychrome sinopia was revealed under one of the floor panels. The palette of colours includes red and yellow ochre, green earth, carbon black and the valuable red pigment cinnabar, all applied with the fresco technique, as attested by microstratigraphy.