Documentation, investigation and analysis of a rare archaeological cartonnage object from the Egyptian Museum in Cairo, Egypt, using non-invasive methods

Abstract

Technical and analytical investigations were carried out on an overhead mask of woman cartonnage from the Egyptian Museum in Cairo (catalogue 33279), which dated back to the Greco-Roman Period. Various non-invasive techniques were used in this study such as: AutoCAD program, multispectral imaging with Ultraviolet and Infrared Rays, optical microscope, X-ray fluorescence spectrometry (XRF), and Fourier transform infrared spectroscopy (FTIR). The structure of the cartonnage was unique and consisted of three distinctive layers, from the bottom to the top; a double layer from linen, a calcite-based plaster layer, and finally a polychrome paint layer. The study of the paint layer revealed the presence of blue, red, white, yellow, orange, brown and black pigments. Yellow color was identified as orpiment (As2S3) and yellow ochre (goethite α-FeO.OH + clay minerals) and blue as Egyptian blue (CaCuSi4O10). Two red shades were also detected of which the lighter is red lead (Pb3O4) and the darker is a mixture hematite (α-Fe2O3), red lead (Pb₃O₄) and calcite (CaCO3). Orange was identified as a mixture of orpiment (As2S3) and red lead (Pb3O4), white as white lead (PbCO3)2•Pb(OH)2,and black as magnetite (Fe3O4). The brown pigment, made up of red hematite, red lead, and black manganese, was detected for the first time in the pigment palette of ancient Egyptian cartonnage. The binding medium in linen layer was identified as Arabic gum. The study showed that cartonnage dated back to the Graeco-Roman Period because of the appearance of red lead, orpiment, and Egyptian blue. Moreover, the presence of lead in the components of Egyptian blue is considered evidence that ovens contain lead resulting in changing the manufacturing techniques of Egyptian blue.