A closer look at our stola coffin lid

In my last post about this late 21st/early 22nd stola coffin lid, I referred to it as eye candy.

Overall before treatment image of the stola coffin lid, L-55-16B

Overall before treatment image of the stola coffin lid, L-55-16B.

This coffin is beautiful, and we could discuss how nice it is to look at all day. But in this post, I’m going to focus on some of the more subtle, somewhat less-attractive (but perhaps even more interesting) features that I’ve discovered about this coffin lid as I’ve begun to work on it. In fact, on Friday I spent awhile discussing some of these details with a group of conservators and interns from the Philadelphia Museum of Art (PMA). As I mentioned in my last post, although this coffin has been on long-term loan to us since the 1930s, it still technically belongs to the PMA, so I am carrying out my treatment in close consultation with one of their objects conservators.

Penn Museum conservator Alexis North (far right) discusses a cat mummy with the PMA conservators and interns.

Penn Museum conservator Alexis North (far right) discusses a cat mummy with the PMA conservators and interns.

I always appreciate the opportunity for professional exchange, and I was happy to be able to discuss my plan, including materials and approaches with them. This discussion energized me to get started with the treatment, and that is exactly what I did, almost as soon as they left.

One thing that I noticed in my initial examination is that this coffin lid has been worked on before. There are residues of old adhesives in areas, including an adhesive mixed with a sawdust-like material, especially around the foot of the coffin.

Adhesive residues on an area of exposed wood.

Adhesive residues on an area of exposed wood near the foot.

I have seen these same types of repairs on at least one other coffin in our collection, and while there is no documentation of them, I am suspicious that this treatment was carried out in our museum soon after we acquired this coffin, but long before our conservation lab was established 49 years ago.

The foot of the coffin has another type of repair as well – there are 2 brackets that are held on with screws on the underside of the foot, apparently to secure some of the wood components. This whole area moves when handled, so the brackets and screws will have to come off so that I can better assess what is going on.

Detail of the foot of the coffin, showing the brackets used in an old repair.

Detail of the foot of the coffin, showing the brackets used in an old repair.

There is some very powdery material associated with areas of damage, especially on the face, which appears to be partially due to deterioration of the mud plaster, but also may be due to insect activity. I’ll have to investigate this further over the course of the treatment.

Detail of the powdery material near the left eye.

Detail of the powdery material near the left eye.

And then there are some materials included in the mud plaster, including some course linen threads and even a leaf, which I am documenting as I work to clean the surface.

Detail of a detached piece of mud plaster with linen thread inclusions.

Detail of a detached piece of mud plaster with coarse linen thread inclusions.

L-55-16B_detail7

Detail of an area of damage, which exposes a small corner of what appears to be a leaf caught in the mud plaster.

The next time I post images of this coffin lid, it should be a lot cleaner, as I plan to complete the initial surface cleaning within the next week. More soon about this, and other observations and developments in the treatment.

 

Treating Nespekashuti’s coffin

Many of you may be wondering about Nespekashuti, our New Kingdom mummy whose remains are quite a jumble under his wrappings. As you can imagine, Nespekashuti is presenting some interesting conservation challenges for us. So far I have focused on surface cleaning and trying to understand the extent to which his linen wrappings are damaged. I decided that before I can deal with stabilizing Nespekashuti any further (and making the decisions necessary to do this), I need to address the damage to his coffin.

Overall view of the proper left side of Nespekashuti's coffin (before treatment)

Overall view of the proper left side of Nespekashuti’s coffin (before treatment)

Nespekashuti’s coffin is quite interesting. I’ve only been able to examine the lower half (which he is contained in) so far. It is made of several pieces of wood doweled together, followed by coating with gesso in areas, then the exterior surface is entirely covered with a single layer of linen, which was coated with gesso and painted, and then finally varnished, likely with pistacia resin. Overall, the painted surface of the coffin is in great condition. But there are some structural concerns, including breaks in the wood, separation and movement between different pieces of wood, and separation of the linen, gesso, and paint from the wood substrate.

Detail of the exterior foot of the coffin, showing separation of the linen, plaster, and paint from the wood.

Detail of the exterior foot of the coffin, showing separation of the linen, plaster, and paint from the wood.

Detail of damage on the proper left side of the coffin.

Detail of damage on the proper left side of the coffin.

I’m starting out my treatment by readhering areas where the linen is lifting away from the wood and plaster below. To repair these areas, I’m using a tried-and-true combination of methyl cellulose, methyl cellulose bulked with glass microballoons, and Japanese tissue paper.

Treatment in progress - I'm using clamps to hold areas in place while the adhesive dries.

Treatment in progress – I’m using clamps to hold areas in place while the adhesive dries.

During treatment - image detail showing the same area at the foot of the coffin (seen before treatment in the second image in this post).

During treatment – image detail showing the same area at the foot of the coffin (seen before treatment in the second image in this post).

This is just the beginning! Once I finish working on the areas I can access, I’ll have to move the coffin to a support that allows me to access the underside/back, so that I can better evaluate and treat those areas as well.

Exploring the painted surface of three coffin fragments

Last week, I wrote about x-raying the fragments of a painted wooden coffin, as part of the conservation treatment. The radiographs helped us see what is under the painted surface. We then turned to the painted surface itself. Through cleaning, we revealed how beautiful and well-preserved the decoration is. I described the cleaning process (and linked to a short video showing the process!) in a previous post.

E12617beforeaftercleaning

E12617A-C coffin fragments before (left) and after (right) cleaning

While it was impossible to see the full range of colors on the boards before cleaning, after cleaning we could see that there were several different colors used to decorate the surface, including two different yellows, red, green, black, and paint that appears black but where it is abraded/damaged looks blue. After much experience working on ancient Egyptian painted wooden artifacts, I knew enough to suspect that some of the paint that appears black is actually Egyptian blue.

It appears that there is a lot of black paint here, but not all of this paint was originally black. The yellow arrows point to black paint while the red arrows point to areas that I believe were originally blue.

It appears that there is a lot of black paint here, but not all of this paint was originally black. The yellow arrows point to black paint while the red arrows point to areas that were originally blue.

If you’ve been reading our blog, you are probably very familiar with one of our favorite photography techniques for Egyptian material, visible-induced infrared luminescence imaging. I have written about it previously, where I explain the process and the equipment we use (follow this link to the post).

Sure enough, it worked beautifully to confirm, and to allow us to see the Egyptian blue on this object:

E12617normaIRfalsecolor

Image of the coffin boards in normal light (left), Visible-induced infrared luminescence image (center), False color image (right). Click on the image to see a full-screen version.

All of the darkened/altered Egyptian blue shows up as bright white in the center image above, and the red areas in the false color image on the right help to further visualize where the blue is in relation to the rest of the painted design. Gotta love this technique!

So that’s great for determining the presence and location of Egyptian blue. But what about some of the other colors? I was particularly curious about the two different yellows and the green. In the case of the yellows, are they two different pigments? And as for the green, which pigment(s) were used to produce this color? Without (for the moment – more about that later) knowing the exact time period of this object, I knew there could be at least a couple different options, including Egyptian green (or green frit), and green earth.

To gather more information about these pigments, I carried out portable x-ray fluorescence analysis (pXRF) in select areas on the boards. I collected data from the following areas, marked with colored X’s in the image below:

pXRF analysis locations, with elements detected listed in order of peak height, from large to small

pXRF analysis locations, with elements detected listed in order of relative peak height, from large to small

As you can see, I labeled the image with the findings from the pXRF analysis. It looks like the two different yellows are indeed two different pigments: the darker, more orange-yellow paint contains primarily calcium and iron, suggesting that this is an ochre, while the brighter yellow paint contains calcium, arsenic, and iron. The relatively large amount of arsenic suggests that this yellow was produced using orpiment (arsenic sulfide).

The green paint also contains arsenic, as well as calcium, copper, and iron. So it appears that the green was produced by mixing an arsenic-containing material (orpiment?) with a copper-containing pigment. Due to the lack of any visible-induced IR luminescence in the green areas, I don’t think that these areas could contain any Egyptian blue, so perhaps the green was made by mixing orpiment with Egyptian green. And as you can see, the blue paint does not contain any arsenic, but does contain calcium, copper, and iron, which we expect to find in areas painted with Egyptian blue. Further analysis will be necessary to determine exactly which pigments were used in the yellow and green areas, but we have discovered a lot using these completely non-invasive techniques!

In my next post about this object, I hope to write about the translation and interpretation, for which I’ll need to consult with the museum’s Egyptologists. In the meantime, if you’d like to learn more about green pigments on ancient Egyptian objects, and more applications of multispectral imaging on Egyptian objects, check out this really great video presentation by Kelsey Museum Conservator Carrie Roberts (originally presented at the 2014 ASOR Annual Meeting):

Green Pigments: Exploring Changing in the Egyptian Pigment Palette from the Late to Roman Periods through Multispectral Imaging and Technical Analysis