Comprehensive study of an ancient Egyptian foot case cartonnage using Raman, ESEM-EDS, XRD and FTIR

Abstract

As part of a project concerning conservation of some ancient Egyptian relics excavated from Saqqara, a foot case cartonnage, which could be dated to the Late Period (712-332 B.C.), was investigated. The structure of the cartonnage, along with substrates, ground layers, pigments and paint binders were revealed using multi-analytical techniques. Optical microscopy (OM), X-ray diffraction (XRD), Raman spectroscopy, Environmental scanning electron microscopy with energy-dispersive x-ray analysis of elements (ESEM-EDS) and Fourier transform infrared spectroscopy coupled with attenuated total reflection (FTIR-ATR) were used in this study. The structure of the cartonnage is found to consist of five distinctive layers, from the bottom up; two calcite-based plaster layers which are separated by double linen layers and covered with a polychrome paint layer. The study of the paint layer revealed the presence of three different red shades (light, brilliant, and dark) which consist of a mixture of red ochre and gypsum (CaSO4.2H2O), cinnabar (α-HgS), and red ochre respectively. Two blue shades were also detected of which the darker consists of Egyptian blue [Cuprorivaite (CaCuSi4O10)] while the lighter contains Egyptian blue admixed with gypsum and calcite (CaCO3). Orpiment (As2S3) and yellow ochre (FeOOH) were used to obtain the yellow paint while same pigments in addition to pararealgar (As4S4), calcite and gypsum were used as the beige paint. The pigment palette used was quite complex and is typical of those encountered in the late and Graeco-Roman periods. The only exception is the addition of the yellow pigment pararealgar in the beige paint, which is considered a novelty in cartonnage industry. A proteinaceous binding medium, namely animal glue, was found to be used in both the plaster and the paint layers.