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

Abstract

The scientific dating, using comparative analytical techniques, of an icon which is nei-
ther 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 spec-
troscopy (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 mi-
croscopy 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 identi-
fication of chrome yellow and lithopone was the keynote in dating this icon.