The Ancient Egyptians had a profound belief in an afterlife, combined with a belief that ritual preservation of the body was essential to reach that afterlife. This led to the development of a complex ritual preservation methodology, which from the Middle Kingdom onward included a cartonnage, which as well as its ritual purposes, supported the form of the mummy, and served as a decorative outer coating to the the embalmed body. This cartonnage was made up of multiple layers of linen (and/or occasionally papyrus) cloth, which was then covered with a mixture of gum or glue and lime or gypsum, to form a hard outer surface suitable for painting. As a form of art, cartonnage reached its most elaborate during the Greco-Roman Period, when the Greek and Roman interest in Egyptian religion led to a fusion of Hellenistic and Egyptian styles, and the adoption of the method by a wider section of society. This was accompanied by a shift from the use of linen bandages and stucco during the Middle Kingdom and Third Intermediate Period, to more Papyrus in Ptolemaic Egypt, then to the incorporation of a wider range of materials during the Roman Period.
These cartonnages have been fairly extensively studied, for example a recent study of a Hellenistic cartonnage from the collection of the Egyptian Museum in Cairo found that it comprised a polychrome layer, a calcite-based plaster layer, a mixed mud and sawdust support layer, and a finishing calcite plaster layer, and that this was painted with opiment (a red pigment made from arsenic trisulphide), goethite (an iron hydroxide mineral with an orange or brown tint), Egyptian blue (calcium copper silicate), Madder (a red pigment extracted from the Common Madder Plant), red ochre (iron oxide), an orange pigment made by mixing orpiment and haematite (iron oxide), malachite (a green copper carbonate mineral, sometimes called Egyptian green), atacamite (a green copper halite mineral), gypsum, calcite, gilding (gold leaf), and a binding agent found to be an Animal glue. Another Roman Period cartonnage from Lisht (a village to the south of Cairo) was found to be made of a calcium carbonate layer laid down on a linen base, and decorated with pigments made from Egyptian blue, malachite, and red ochre.
Another study looked at two female Romano-Egyptian mummies from the first century AD, housed in the collection of the Ismailia Museum. These mummies were found to have a linen layer, overlaid by a gesso (glue and powdered limestone) layer, which was in turn overlaid by a pigment layer. Another mummy from El-Lahun in Middle Egypt was found to have a linen layer overlain by a mixture of calcareous material and gum Arabic, which was painted with Egyptian blue, orpiment, yellow ochre (iron (III) oxide-hydroxide, or limonite), red ochre and a green pigment made by mixing together Egyptian blue and yellow ochre.
A study of an earlier cartonnage, from the Late Period (712-332 BC), found that this had five distinct layers, including two layers of calcite plaster separated by a double-layer of linen bandages, and a polychrome paint layer where the pigments cinnabar (mercury (II) sulphate), red ochre, Egyptian blue, Orpiment, yellow ochre, and pararealgar (a yellow-orange arsenic sulphide pigment) bound in an Animal glue. This was a pigment palette just as complex as that used in the Greco-Roman Period, which came as a surprise. A study of Greco-Roman cartonnage fragments from Hawara, at the entrance to the Fayyum Oasis, found that these typically had a layer of course ground material, typically calcite with traces of quartz, followed by a layer of finely ground material, usually purer calcite, painted with a mixture of Carbon black, goethite, Egyptian blue, and red lead pigments mixed with animal glue. Another study of mummies from Tell Al Sawa in the Eastern Delta, showed that these had a linen layer overlain by a layer of ground calcite bound with Animal glue.
Finally, a study of a Greco-Roman Period gilded cartonnage with polychrome decoration from the Saqqara Necropolis found that this comprised a double layer of linen soaked in gum, followed by a course ground layer of calcite and humtite, followed a fine ground layer of calcite, then a gilded layer, painted with haematite and orpiment pigments, which were bound with gum Arabic.
Investigating the materials used to construct and decorate cartonnages enables archaeologists not just to understand the methodology of the people who made these objects, but also to come up with appropriate ways to preserve them. However, cartonnages have proven to be quite diverse in their construction, so that it is difficult to come up with a preservation method ideal for all of them, and the techniques which have been used to investigate them to date have been destructive in nature.
In a paper published in the Journal of Historical Archaeology and Anthropological Sciences on 9 March 2023, Omar Abdel-Kareem of the Archaeological Conservation Department at Cairo University, and Raghda Mahmoud, Eid Mertah, and Azza Fathy of the Conservation Center at the Grand Egyptian Museum, present the results of a study of a Greco-Roman Period cartonnage mask from the collection of the Egyptian Museum, which used non-invasive techniques to examine the materials from which the mask was made.
The cartonnage is a mask of a woman from the Greco-Roman Period, part of a set which included overheads, collars, pectorals, aprons, shin pads, foot cases and ankles. The mask is 30 cm high and 34 cm wide, and mostly painted in red, with large eyes and black brows, as well as being decorated with jewelry, including earrings and a necklace.
A three-dimensional map of the cartonnage was made in AutoCAD, based upon photographs taken with a digital camera. The mask was examined under ultraviolet and infrared light, then studied with Dino Lite and Keyence microscopes, and finally an ELIO portable X-ray fluorescence spectrometer and a Bruker Fourier-transform infrared spectrometer.
The initial AutoCAD reconstruction of the mask revealed that the item was dirty, and suffering from damage including cracks, paint flake loss, and buckling in the linen layer.
Examination under ultraviolet light produced bright white emissions from the eyes and earings of the cartonnage, which suggests that these areas were painted with white lead, while the base of the cartonnage showed up as a yellow-white colour, probably indicating the usage of recycled textile material or gum Arabic. The ultraviolet light also highlighted the textile composition of the mask, as well as the dirt accumulations, cracks, and stains. More positively, it uncovered no signs of prior attempts at restoration, nor of the material being dyed or attacked by micro-organisms.
Examination under infrared light caused the crown and necklace of the mask to show up as bright white, while other areas appeared dark. This probably indicates the use of Egyptian blue paint. This method also showed a black paint has been used on the mouth and parts of the face.
The cartonnage was found to be made up of three layers, a double layer of linen, a calcite plaster layer, and a polychrome paint layer.
Microscopic examination of the textile of the cartonnage suggests that it is a plain weave made from an s-spun (counterclockwise spun) thread. Some parts of the fabric were discoloured to a dark brown, resembling burns, but which is more likely to have been caused by gum Arabic.
Microscopic examination of the plaster layer showed the presence of shiny particles, which X-ray fluorescence spectroscopy identified as calcium carbonate, with some iron impurities. This was in places painted with a yellow orpiment.
X-ray fluorescence examination of the yellow pigment used showed the presence of arsenic and sulphur, strongly suggesting that the colour was orpiment (arsenic sulphide), although traces of iron were also present, suggesting that some goethite was present.
The blue areas of the cartonnage was found to comprise particles of a blue pigment applied over a calcite base. The pigment was found to contain calcium, silicon, and copper, strongly suggesting Egyptian blue (calcium copper silicate). Traces of iron and lead were also found, suggesting impurities, and possibly the preparation of the pigment in an oven also used to prepare lead-based paints. Egyptian blue was used in Egypt from the Fourth Dynasty (Old Kingdom) onward, and spread around the Mediterranean Basin during the Roman Period.
The black pigment was thickly applied on the eyebrows, and had cracked in places. X-ray fluorescence examination found the presence of iron, implying the pigment used is magnetite, plus calcium, which probably comes from the underlying calcite layer, and chlorine, which may be an impurity, possibly from the dirt which had accumulated in this area.
The white pigment produced spectra for lead, confirming that this was a white lead (lead carbonate); traces of iron and calcium where also found, again probably representing impurities and the base-calcite layer.
Two different red pigments were present, with the lighter apparently being red lead (lead oxide), and the darker being a mixture of red lead, haematite, and calcite. Red lead was also apparently present in the orange pigment, combined with yellow orpiment, and goethite (iron hydroxide). The brown pigment was found to contain a mixture of red hematite, red lead, and black manganese, something not previously seen in an Egyptian cartonnage. Examined under the microscope, this pigment showed as a mixture of purple or burgundy and yellow grains.
A filler was found inside the crown of the cartonnage, which X-ray fluorescence examination suggested to be a mixture of calcite and orpiment.
Abdel-Kareem et al.'s study revealed a great deal about the materials used to manufacture a Roman-period Egyptian cartonnage, for the first time using non-invasive techniques which left the artifact intact. As well as being a proof-of-concept for this method, the study was able to provide new information about the methods used by the cartonnage-makers, including the apparent baking of Egyptian blue in an oven also containing lead (which would have caused the pigment to be brighter). This was achieved despite the fact that the cartonnage was dirty, cracked, missing its paint in places, and showing signs of buckling, demonstrating that these techniques are relevant to conservators in the early stages of preserving ancient objects.
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