DATING A COPTIC ICON OF ANONYMOUS PAINTER BY SPECTROSCOPIC STUDY OF PIGMENT PALETTE

The scientific dating, using comparative analytical techniques, of an icon which is neither dated nor signed was undertaken. This icon is not attributed to any known painter; therefore one should rely on the pigment palette applied for dating. The icon under study is located in Saint Abanoub church in Samanoud, in Egyptian Delta, representing the equestrian Saint George fighting a dragon. The analytical instruments chosen for this study were; optical microscopy, Raman microscopy and Fourier transform infrared spectroscopy (FTIR). Optical microscopy was used to study the layered structure of the icon which comprised a wooden panel, an imprimatura layer underneath some paint areas, multiple paint layers and a varnish layer. The absence of both the canvas and the white ground layer was apparent. The pigment palette was determined by means of Raman microscopy and the identified pigments were Prussian blue, ultramarine blue, vermilion, chrome yellow, lead white, lithopone and carbon black. These pigments were used solely or combined in complex mixtures to reveal the desired paint shades. The FTIR was used to determine the protected varnish layer as well as the paint medium applied. The identification of chrome yellow and lithopone was the keynote in dating this icon