The artistic style employed by the Pharaonic Egyptians is probably the most readily recognisable art form from the ancient world. These paintings are highly formalised, giving them an aesthetic consistency that persisted for thousands of years. This style has been studied since the nineteenth century, with early archaeologists developing a framework by which it is thought the ancient artisans operated. It has been calculated that the flattened plaster wall, then typically separated into a number of modular grids which served as panels for the depiction of the artwork. The art was then sketched onto the walls with red ochre, after which the background was filled in with white or black pigment, leaving the figures free. Colour was then applied to the figures, typically in several layers, with some mixing of pigments achieved by this. Finally, details were added to the pictures, and any pigment spilling onto the surrounding area was overpainted with more white. The understanding of this process was built up by studying uncompleted artworks from 18th and 19th dynasty tomb chapels (these dynasties, which formed the high point of New Kingdom political power, are generally considered to be a high point for this artistic style). The presumption that this methodology was used in other periods should therefore be taken with a degree of caution, even if the artwork from different times looks similar.
Some of these ancient artworks are known to have been altered after they were made, although, since most of this art has only ever been studied visually, it is unclear how widespread this practice was. We are able to say that an artwork was altered if it was done in a way that left the original art showing, or if subsequent chemical reactions have led to covered layers of paint becoming visible. Other alterations, however, are beyond the reach of an archaeologist working with eyes alone.
In a paper published in the journal PLoS One on 12 July 2023, Philippe Martinez of the Laboratoire d’archéologie moléculaire et structurale at the Sorbonne Universite and the MissionArchéologique Française de Thèbes-Ouest, Matthias Alfeld, also of the Laboratoire d’archéologie moléculaire et structurale at the Sorbonne Universite and of the Department of Materials Science and Engineering at Delft University of Technology, Catherine Defeyt of the Centre européen d’archéométrie at the Université de Liège, Hishaam Elleithy, also of the Mission Archéologique Française de Thèbes-Ouest, Helen Glanville, also of the Laboratoire d’archéologie moléculaire et structurale at the Sorbonne Universite, Melinda Hartwig of the Michael C. Carlos Museum of Art at Emory University, François-Philippe Hocquet, also of the Centre européen d’archéométrie at the Université de Liège, Maguy Jaber, again of the Laboratoire d’archéologie moléculaire et structurale at the Sorbonne Universite, Pauline Martinetto of Physique, Lumière Matière at the Université Grenoble Alpes, David Strivay, again of the Centre européen d’archéométrie at the Université de Liège, and Philippe Walter, once again of the Laboratoire d’archéologie moléculaire et structurale at the Sorbonne Universite, describe the results of a study in which X-ray fluorescence imaging was used to study Ancient Egyptian paintings in situ.
X-ray fluorescence imaging works by bombarding surfaces with X-rays, then using a spectrograph to identify specific elements by the frequencies at which they fluoresce. In the past decade much more portable X-ray fluorescence imaging equipment has come onto the market, which it is possible to set up in locations such as, in this instance, Egyptian tombs.
In order to assess the value of their method, Martinez et al. examined paintings in two New Kingdom tomb chapels from the Theban Necropolis; that of Menna, an overseer of cadastral surveys under Amenhotep II, who lived from 1391 to 1353 BC, during the 18th Dynasty, and Nakhtamun, Chief of the Altar in the Ramesseum (Temple of Ramesses II), who died in about 1100 BC, during the 20th Dynasty.
The first painting discussed is within the tomb chapel of Menna, and was first observed to have been altered when the tomb was opened in 1888. The alteration is quite visible to the naked eye, although this was presumably not the case when the tomb was sealed; it has been assumed that the alteration become visible again due to chemical interactions between the original pigment and the paint which was used to cover it up, which has apparently enabled the dyes to migrate to the surface layer. The altered area has been shown to fluoresce under ultraviolet light, something which may show the presence of an organic binding agent, or a breakdown product of one of the paints used. The scene depicted shows Menna and his wife, Henuttawy, worshipping the god Osiris. Menna is standing with both hands held in front of his face. Close examination of the figure of Menna shows a second left hand, in a slightly different position to the final one, which has apparently been painted over. The alteration has moved the hand only slightly, for what to a modern eye appear to be aesthetic reasons, although it is clearly problematic to assign modern motives to ancient artists.
The fact that this painting was altered is clear, but many questions remain about this alteration. It is uncertain whether the original position of the arm was identified as wrong immediately, or whether the artwork was completed and later altered, perhaps because the artist, or his patron, decided that the original position was in some way objectionable. Could there have been a long interval between the completion of the artwork and the decision to alter it? The wash that overlays the old arm appears to match the rest of the wall, which may indicate that the alteration was made quickly after the arm was painted.
Surprisingly, X-ray fluorescence imaging revealed that the two versions of the arm appeared to have been painted with a quite different set of pigments. The first arm has a much higher arsenic content than the arm which replaced it (the red pigment realgar and the yellow pigment opiment, both widely used by Egyptian artists, were both forms of arsenic sulphide), although arsenic is still present in the second arm, and the highest arsenic content is found where the second arm overlays the first arm.
Based upon this, Martinez et al. conclude that the second arm was painted directly over the first arm, without any attempt to obscure the earlier version at this stage, with the overpainting of the original arm occuring at the end of the process, as with more minor mistakes. This is different from the way in which modern artists tend to work, which would typically involve painting over the older version to create a blank surface on which the new arm could be painted, and has created a darker patch where the two arms overlay one-another. This darker patch appears unseemly to modern viewers, but may not have been visible to the original artist, who was using an opaque iron ochre-rich paint mixture to cover the original arm, with the darker area possibly forming in the intervening three thousand years due to chemical reactions between the paints.
Martinez et al. also note that the golden bracelet of Menna appears to have been painted with an arsenic-based pigment, presumably opiment. There is also a strong correlation between the presence of copper and areas of blue and green pigments on the painting, which appears to confirm the use of the pigments Egyptian Blue and Egyptian Green, both forms of calcium copper silicate. The undercoat over which the paintings were made shows the presence of calcium but not sulphur, suggesting that this was a calcium carbonate based paint.
The differing pigment compositions of the two versions of the arm may be indicative of the process that was used to paint the tomb. Large paintings of this type are known to have been the work of more than one artist, with a previous analysis of the brush-stroke technique in the tomb of Menna having led to the conclusion that at least four artists were involved. If this were the case, then a second version of the arm, painted with different pigments, could imply that the correction was made by a second, presumably more experienced, artist, who found fault with the work of the first atist for some reason.
The Ramesside period tomb chapel of Nakhtamun contains a portrait of Ramesses II, which has led to the conclusion that the tomb probably dates from that pharaoh's reign. Unusually, the pharaoh is depicted with a budding beard, a symbol of grief, leading to the suggesting that this painting relates to the death of Seti I, his father, and Ramasses' subsequent assent to the throne. However, Ramasses II stands beneath a cult-canopy, with the figure before him being the god Ptah, not Seti I (which would be expected if he was in the act of mourning his father). Another odd feature of this picture is that Ramasses II has a protruding Adam's apple, a feature usually absent in Egyptian iconography.
X-ray fluorescence imaging analysis of this image showed that green and blue areas of the painting had high levels of copper, as might be expected if the pigments Egyptian blue and Egyptian green were being used. Copper can also be observed in places where the blue has almost faded beyond visual perception. All of the copper pigments are within the red outlines of the picture, confirming that the pigment painters were filling in a pre-drawn outline.
The distribution of iron in this painting matches well with the distribution of the colours red and yellow, suggesting the use of the pigments haematite (iron oxide) and goethite (iron oxide-hydroxide). It is also present in areas with partially transparent clothing, probably indicating a layer of partially transparent white pigment being applied over a red pigment.
Arsenic is also present in the red and yellow areas, probably indicating an aresenic-based pigment had been mixed into the iron-based one. However, the match between the arsenic distribution and the final colour distribution is not identical, possibly suggesting some corrections. Notably, an earlier version of Ramesses sceptre appears to have been in contact with his chin, while the final version has a gap. close examination of the area between the sceptre and the chin revealed cracks in the white paint, with a yellow pigment, presumably opiment, showing through. The outline of the golden forehead-piece of the pharaoh's crown is also painted in arsenic-based pigment, although the centre of the same piece shows no trace of this. Interestingly, comparison of the X-ray fluorescence image to the currently visible painting shows that this outline has been entirely covered over by the red pigment of the face, with only the non-arsenic (goethite?) centre of the piece showing.
Martinez et al. were able to draw red outlines onto the image of the painting, which neatly outline the copper and iron distributions, as well as the current distribution of colours. However, the distribution of arsenic pigments appears quite different, apparently showing an earlier version of the portrait, which was then painted over. Arsenic is also present in the exposed flesh areas of the picture, but not in the parts where the flesh was covered by semi-transparent clothing. Examination shows the face of the pharaoh appears to be made up of two different pigment, with a red ochre (haematite) layer overlain with a more orange pigment, possibly realgar. Alternatively, the skin tone could have been created by mixing iron and arsenic based paints, with the exposed and covered skin being different elements of the picture painted with different pigments.
A patch of arsenic is also visible to the left of the head of Ramesses, where no detail exists today. This may relate to the shape of the kapresh-crown the pharaoh is wearing, which has visibly been altered, and is unconventional in shape, having an unusually elongate form, with the gold band at the rear being atypically short. Thus the patch of arsenic close to the pharaoh's ear may represent a former, more conventional form of the crown, which was overpainted for some reason.
Martinez et al. consider the distribution of arsenic on the portrait of Ramesses II to be a reflection of an earlier version of the image, painted at least in part in opiment, which was later overpainted. They note that this seems to particularly affect the pharaonic insignia, such as the khepresh-crown, the heka-sceptre and the wesekh-necklace. The original version of the sceptre appears to have been a straight line with a leftward curve at the end, while the final version is a more conventional form with a nearly circular top. The golden forehead piece of the khepresh-crown formerly had corners underlined with golden paint, which were later painted over.
Opiment is known to degrade over long periods of time, and many Egyptian pictures suffer from colour spreading as this pigment degrades into a more mobile form. However, Martinez et al. do not believe this is the case with the portrait of Ramesses II, as there are no gradients at the edge of the arsenic areas, which would be expected with spreading, rather the pigment appears to conform to strict outlines which were then rejected.
The surviving portrait of Ramasses II is depicted wearing a wesekh-necklace, a flat, disc-like piece of jewellery with an opening for the head, worn by many royal and divine figures during the nineteenth dynasty, and indeed throughout much of Pharaonic Egypt. However, the arsenic distribution appears to show a shebyu-necklace, which is a heavy necklace made up of several chains of large gold beads. Such necklaces were common depictions during the reigns of Amenhotep III and Amenhotep IV (Akhenaten the Heretic), and then from the twentieth dynasty onwards. This strongly suggests that Nakhtamun did not serve Ramasses II when he was a living pharaoh during the nineteenth dynasty, but rather as a priest of the dead and deified pharaoh during the twentieth dynasty. Apparently, some time after the original portrait was painted, it was realised that this feature was anachronistic, and was replaced with a more appropriate feature (which would show an awareness or at least consideration of changing fashion absent in medieval and renaissance European art, where biblical characters are typically shown in contemporary costumes). This re-dating of Nakhtamun as a twentieth rather than a nineteenth century figure would also help to explain the elongated nature of the figures in the chapel, which are more typical of the later period.
Martinez et al. note that this re-dating of Nakhtamun is very much a working hypothesis at this time, and that they consider the retouching of the figure of Ramesses II a difficult and complex issue, unlike the more simple and straightforward alterations in the tomb chapel of Menna. Such a change in the decoration of a pharaoh almost certainly has some symbolic meaning that is lost to modern observers, and it needs to be remembered that we are often ignorant of what was truly important to the living Egyptians, or other long departed peoples.
Ancient Egyptian art is highly structured, and its creation was a highly formalized process. However, the examples Martinez et al. examined appear to show that this formalized process could clearly be varied significantly if the need to do so was perceived by the artists - although it is always problematic to draw conclusions from a small number of examples.
The advent of portable X-ray fluorescence imaging technology means that this methodology is no longer confined to the laboratory. Martinez et al. have applied this technology to examine the layering of paint in Egyptian tombs for the first time, and used it to develop a new hypothesis about the history of one of the two tombs examined. This demonstrates the usefulness of the technology, although the hypothesis developed from this study will need further investigation before they can be taken as truly meaningful.
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