Consolidating a painted wooden shabti

This one-minute video captures what I did at work today, times about 250.

Shabti paint consolidation (click on the link to view the video)

To put it into context, I was working on this painted wooden shabti, which I’ve mentioned on the blog before.

The area blocked out in yellow is the area I'm working on in the video.

The area blocked out in yellow is the area I’m working on in the video.

Here is a still shot of the area I’m working on in the video, taken at 10x magnification using our binocular microscope:

IC800006The paint is actively flaking in many areas on this object. In the video, you can see me applying a 2% solution of methyl cellulose in water by brush to a loose flake of paint, and then after allowing the flake to relax, tapping it into place using a silicone colour shaper. It’s slow-going, but it’s working!


Is there an archaeobotanist in the house?

Fortunately for us, the answer is yes.

Following up on my recent post about identifying the wood used to make this Middle Kingdom painted wooden coffin, I showed the images of the thin sections I cut from some detached wood fragments to Dr. Naomi Miller, our resident archaeobotanist. Dr. Miller typically deals with really degraded material, often tiny pieces of charcoal, so she was delighted to see that these samples showed enough information to make a more definite identification. AND, much to my delight, she confirmed my hunch that these boards are made of acacia.

Here are the images she used for comparison, found in Anatomy of European woods, by Fritz Hans Schweingruber.

acacia references

Reference images of Acacia cross-sections (left) and tangential sections (right)

And here they are, side-by-side with our samples:

wood comparison cross sections

In the cross-sections, we see pore multiples and uniseriate rays

wood comparison tangential sections

In the tangential sections, we see mostly uniseriate rays, with some biseriate rays.

We compared our samples’ images with images of ash and carob in the same book, since these were also candidates originally, but there were enough differences for us to exclude these as possibilities. It is possible that there is something that we are not considering, but I think that I’m convinced by this work that this coffin was made with acacia.


Out with the old, in with the new

There are some new objects to see in the lab!

Just this week, we began returning some of our recently-treated objects to storage and exchanging them for some new stuff, including a painted wooden coffin (this is a photo of the coffin box without the lid – note the elaborate painted decoration on the interior):

coffina falcon coffin and “mummy” (I’m putting “mummy” in quotes here because this mummy looks like it’s a corn mummy, made by wrapping up a mixture of sand, grains, and plant fibers):

falconmummythese pieces of a painted wooden coffin board with two Wedjat eyes:

coffinboardand this ibis mummy, with exposed feathers!

ibismummyThere are some other things too, including some cartonnage and another animal mummy, which we’ll post photos of soon.

As always, these photos really don’t do these objects justice. You’ll have to come check them out in person! And we’re only just starting to examine them, so we’ll definitely post information as we learn more. If you have specific questions about any of these objects, please let us know!


Wood ID

I’m currently treating 7 fragments of a painted wooden coffin from Abydos. Lately, many of our visitors have been asking what kind of wood was used to make this coffin. This has actually been a question that we have been asking ourselves, and we are trying to see if we can come up with an answer.

In ancient Egypt, large timbers for coffin-making were scarce, so the wood was either imported from places like the Mediterranean, the Near East, or from other parts of Africa, or the Egyptians would cobble together smaller pieces of wood from local sources. Based on previous studies, we have a finite list of types of wood that are known to have been used, but from there we need to move to looking at the object itself.

These images show the exposed wood on the side (left) and back (right) of one of the coffin fragments. Can you guess what type of wood this might be?

These images show the exposed wood on the side (left) and back (right) of one of the coffin boards. Can you guess what type of wood this might be?

As conservators, we are educated not only in object treatment, but in the analysis of objects, and the examination of tiny fragments of objects, like plant and textile fibers, wood, and pigments. But many of us don’t do wood ID all that often, so it can take awhile to get set up, to re-orient ourselves to what we’re seeing in the samples, etc. AND it requires a sample, which we don’t often have access to. Fortunately, for me, I have some already detached samples from these boards and access to someone who does this type of work more frequently, archaeobotanist Dr. Naomi Miller, so I turned to her to help me with this work.

Dr. Miller looked at the samples I had and selected one that looked promising, due to the exposed cross-section on one end. I mounted this sample under our binocular microscope and took a photo, to help her study it further and compare to known reference samples.


The wood fragment with exposed cross section, 60X magnification

From this sample, Dr. Miller was able to determine that this is a hardwood, based on the presence of clearly visible rays and thick-walled pores, many of which are radially paired (pointed out below).

Slide4Based on these features and the known types of hardwoods used in ancient Egypt, this helped narrow down the likely possibilities to Common ash (Fraxinus excelsior L.), Carob (Ceratonia siliqua L.) and Acacia (Acacia sp.). Dr. Miller considered other types but ultimately excluded willow (Salix), oak (Quercus), elm (Ulmus) and sycamore fig (Ficus sycomorus) due to either the presence or absence of certain features.

In an attempt to further narrow down the possibilities, I cut thin sections from the sample that Dr. Miller examined, from the cross-section and tangential surfaces, and wet-mounted them on glass slides. Looking at these thin sections with our polarizing light microscope (PLM), I was able to see some of these features a bit more clearly.

Cross-section, 50X magnification

Cross-section, 50X magnification

In the cross-section above, the pores are visible as solitary or paired, and mostly uniseriate (1-cell wide) rays are visible. The tangential section also shows mostly uniseriate rays, but some bi-seriate rays are visible as well.

Tangential section, 50X magnification

Tangential section, 50X magnification

Cutting these sections from the wood sample, which was quite degraded, was difficult and unfortunately I’m not really able to pick out many other features from the sections that I examined. I will have to get Dr. Miller to weigh in on this again, but in the meantime, I’m going to go out on a limb and say that I’m leaning toward this wood being acacia. One thing I forgot to mention is that the wood of the coffin board fragments is a deep red-brown color. Acacia is known for being a red, hard, and durable wood, and while it produces small timbers, we know that it was used for coffin-making, among other things.

Completing the treatment of Tawahibre’s coffin

Things have been pretty busy around here lately, and I almost forgot to post some updates about several projects. One project in particular is the treatment of Tawahibre’s coffin. We have been working on this 2-part painted wooden coffin in the lab for the last year, and we recently completed its treatment.

As you may remember, when the coffin first came up here, it was covered with a thick layer of dust and grime, the paint was badly flaking in areas, several large pieces of painted gesso were pulling away from the wood support, and there were large cracks throughout.

Before treatment photos (clockwise from left): upper half of coffin showing layer of dust and large cracks and losses; large piece of painted gesso partially detached from top of head; large loss on wig, showing old animal glue adhesive from a previous restoration

Before treatment photos (clockwise from left): upper half of coffin showing layer of dust and large cracks and losses; large piece of painted gesso partially detached from top of head; large loss on wig, showing old, shiny animal glue adhesive from a previous restoration

After cleaning the surface with a brush and vacuum, followed by cosmetic sponges, I consolidated the paint with a methyl cellulose solution, filled in cracks and gaps using Japanese tissue paper and a mixture of methyl cellulose bulked with cellulose powder and glass microballoons, and then toned the fills with acrylic paint. This work is explained in further detail in previous posts, which you can find by clicking on the links included in blue above.


A detail shot of the wig showing an area with several large open cracks before and after filling with Japanese tissue paper and methyl cellulose/cellulose powder/glass microballoons mixture

Based on a discussion with our Egyptian section curators, I also made some aesthetic fills to mask some large losses, including 2 losses on the wig. We chose not to fill the losses on the nose and chin because filling these losses would require too much guess-work as to the original contours of these features.

Large loss on wig before (left), after application of Japanese tissue paper layer (middle), and after application of fill mixture (right)

Large loss on wig before (left), after application of Japanese tissue paper layer (middle), and during application of fill mixture (right)

Detail of the head and wig before (left) and after (right) conservation treatment, with losses in before treatment photo outlined in red

Detail of the head and wig before (left) and after (right) conservation treatment, with losses on the wig outlined in red. The larger loss on the right is the featured in the previous series of images.

I carried out similar work on the base of the coffin, and now both are complete:

Tawahibre's coffin lid before (left) and after (right) conservation treatment

Tawahibre’s coffin lid before (left) and after (right) conservation treatment

The coffin base before (left) and after (right) conservation treatment.

The coffin base before (left) and after (right) conservation treatment

As you can see, we chose not to fill many of the losses, focusing instead on stabilization.

This work will enable future exhibition of the coffin, and just as importantly, it will make further study of the coffin possible. All along there have been some discrepancies between the name that has always been associated with the coffin (Tawahibre, a woman’s name) and a previous translation in 1946 of the hieroglyphic text on the coffin (which identified the name of a male court official, the son of J-se(t)-N-Ese). There has also been some confusion about the remains once housed in the coffin, which were previously identified as male, but in a 1975 autopsy the remains were confirmed as belonging to a female in her mid-30s. A bit confusing, but hopefully we’re now one step closer to getting this all straightened out!


Fragmentary painted coffin from Abydos

If you are a member of the museum, you may have already seen some information about these painted coffin board fragments in the most recent issue of Expedition magazine:

E12505_2These fragments, which date to the Middle Kingdom (ca. 2000-1700 BCE), were excavated from the North Cemetery of Abydos in 1901 by John Garstang. The museum supported Garstang’s work through the Egypt Exploration Fund.

Despite the severe insect damage, the preservation of the painted details on these fragments is remarkable.

This fragment features 3 usekh collars, which were often reserved for nobility. Beside each collar is a mankhet, or counterpoise. The hieroglyphs above are the names of each of the collars, which are slightly different.

This fragment features 3 usekh collars, which were often reserved for nobility. Beside each collar is a mankhet, or counterpoise. The hieroglyphs above are the names of each of the collars, which are slightly different.

A detail of the usekh en nebti, the collar of the two mistresses that incorporates the uraeus and the vulture

A detail of the usekh en nebti, the collar of the two mistresses that incorporates the uraeus
and the vulture (7.5x magnification)

These coffin board fragments have never been exhibited, and our renewed interest in them is due to the fact that we are currently excavating tombs from the same time period in South Abydos, including the funerary complex of Senwosret III. You can read a lot more about this project in the recent Expedition issue and on the museum blog by following this link.

In order to exhibit the coffin fragments, they need some extensive conservation treatment. Their surfaces are dirty, the paint is cracked, cupped and lifting from the wood support, and is very fragile, and some of the boards are structurally unstable due to the extensive insect damage.

We are currently working on these boards in the lab, and we have made some good progress. We are cleaning the painted surfaces with a kneaded rubber eraser. The eraser can be shaped to a fine point, and working under the binocular microscope, it is possible to remove the dirt from most of the painted surface without disturbing the fragile paint.

We are using kneaded erasers (left) to clean the delicate painted surface of these coffin boards (right)

We are using kneaded erasers (left) to clean the delicate painted surface of these coffin boards (right)

Some areas of paint need to be stabilized before they can be cleaned. After testing a variety of adhesive solutions, I settled on my old friend methyl cellulose, a 2% solution of methyl cellulose in water to be exact, to consolidate fragile areas.

Paint consolidation is being carried out under the microscope with a fine brush

Paint consolidation is being carried out under the microscope with a fine brush

I am now working on testing some fill materials, both to stabilize the edges of lifting paint and also to stabilize the fragile wood. I will post an update as soon as I make some decisions and proceed with this part of the treatment!


Investigating the shabti box coating

Last month, I wrote about a new challenge in the lab, otherwise known as this shabti box and its associated shabtis:

front compressedAt first the box came into the lab with 3 shabtis, and then we found that there were 3 more in storage that may belong with the box as well. 4 of the shabtis are very similar in appearance whereas the other 2 are slightly different, so they may actually not be associated after all. Can you spot the 2 different shabtis?

2 of these things are not like the others...

2 of these things are not like the others…

All of these objects are made of wood, gesso, and paint. And as you can see, all of them have an orange-yellow coating on their surfaces. In my last post I posed the questions “what is this coating?” “is it an original varnish or is it a later restoration?”. My initial guesses were that it is either an original pistacia resin varnish, a later cellulose nitrate (or other old restoration adhesive) coating, or a combination of the two.

Well, there are several things we can do to try to answer these questions and to narrow down the possibilities. One of the first things I did was to look at these objects very carefully using our binocular microscope. I could see that the coating was applied unevenly, especially on the box, and that it is actively cracking and flaking. Another thing that I noticed was that there are areas on the box where the paint is lost and where the coating extends over the loss onto the gesso below.

A detail shot of one side of the shabti box - the yellow arrows are indicating areas where the coating extends over an area of paint loss onto the gesso.

A detail shot of one side of the shabti box – the yellow arrows are indicating where the coating extends over areas of paint loss onto the gesso.

Usually, this would indicate that the coating was applied after the damage occurred (so sometime after excavation, either in the field or soon after coming to the museum). So this is one clue, but doesn’t really answer my questions.

Next, I examined the shabti figures under ultraviolet (UV) light. In conservation we routinely use UV examination to characterize materials and to distinguish old restoration materials from original materials – for instance, shellac, used historically to repair objects, exhibits a characteristic bright orange fluorescence under UV. (For a great explanation of UV, along with some interesting images, check out this post on UV examination by my colleague Allison Lewis, conservator at UC Berkeley’s Phoebe A. Hearst Museum of Anthropology.)

The coating on the box and the shabtis has a yellow-orange appearance under UV – but not the bright orange that we expect to see from shellac.

shabti UV

4 shabti figures under UV light

So UV examination was helpful (it eliminated shellac as a possibility) but didn’t answer my questions either.

Next, I did a microchemical spot test on a couple of the previously detached flakes of the coating. We’ve used spot-testing before in the lab – the last time I wrote about it was in reference to the mystery fibers on Tawahibre’s coffin. In this case, I carried out a spot test for nitrates using diphenylamine (according to instructions in Material Characterization Tests for Objects of Art and Archaeology). Using this test, a sample containing nitrates will turn blue once a solution of diphenylamine/sulfuric acid is added. Below you can see the result of the test on one of the coating flakes from the shabti box (left) and the test on a control sample of cellulose nitrate adhesive (right).

Left: coating sample from the box after spot test (negative result) Right: control cellulose nitrate adhesive after spot test (positive result)

Left: coating sample from the box after spot test (negative result) Right: cellulose nitrate control after spot test (positive result)

Based on these results, it seems that the coating does not contain cellulose nitrate. This does not mean that the coating does not contain another recently-added adhesive. We have a few other ways of narrowing down the possibilities even further, and I will write about our continued work on this in my next post.


A new challenge in the lab

I am always pleased to see returning visitors to the Artifact Lab. And of course, people who have been here before want to know, what’s new? Visiting the lab is the best way to find out about our latest projects and progress, but this blog is the next best thing.

So, what is new around here? Well, I’ll let you take a look for yourself:

shabti boxThis object was featured in the “What in the World” series on the museum’s Facebook page this week. There were a wide range of guesses as to what this is; my favorites being a breadbox, an Egyptian mail box, a papyrus organizer, a holder for cat mummies, and an ancient Egyptian Matchbox-car garage.

Seriously though, this is a shabti box. Here is a shabti box that is similar in style, at the British Museum. Shabti boxes were used to house shabti figures. Shabtis were included in burials as servant figures that would carry out heavy work on behalf of the deceased. They were depicted as mummified and were inscribed with spells which, when recited, magically caused them to come to life and perform work for the deceased in the afterlife. Here are 3 shabtis that were originally housed in our shabti box:

shabtisThe shabti box and shabtis are made of wood, covered with a thin layer of gesso, and painted. They are in the lab for treatment because their surfaces are actively flaking. Not only is the paint flaking, but there is a yellow-orange coating over the painted surface that is badly flaking as well.

This yellow-orange coating is applied over the entire surface of the shabtis and the box (inside and out), and it is very thick in areas.

A detail of the shabti box showing areas where the coating is particularly thick (pointed out here with the red arrows).

A detail of the shabti box showing areas where the coating is particularly thick (pointed out here with the red arrows).

My first question is, what is this coating? Is it an original varnish or is it a later restoration?

The box and the shabtis date to the New Kingdom, ca. 1200 BCE. We know that varnishes such as those containing pistacia resin were used on painted wood in the New Kingdom, and these varnishes often appear yellow, although they may not have been yellow when first applied. We also know that these varnishes were applied unevenly – the application of the pistacia resin varnish has even been described as “messy” and it is acknowledged that its purpose was not an aesthetic one, but rather intended to make such objects more divine, or suitable for the afterlife (Serpico and White 2001). This description may help explain the rather sloppy appearance of the yellow-orange varnish on our shabti box and figures.

We cannot, however, discount the idea that this coating may be a later restoration. We know that archaeologists frequently stabilized artifacts in the field to allow for their safe recovery. Materials such as paraffin wax, gelatin, shellac, and cellulose nitrate have been used for this purpose in the field or once the objects found their way into museum collections (like the wooden heads Laura has been working on).

There are several ways in which we can try to determine what this coating is and when it may have been applied. We already have some clues, but we’ll share those in an upcoming post. Stay tuned for updates as we learn more!


Flippin’ coffins

We’ve been threatening to do it, and this week we followed through on our promise – to flip over the base of Tawahibre’s coffin.

As readers know, we have been working on Tawahibre’s coffin lid, and recently lifted it away from the base. Once we removed the lid, we could see that the interior of the base was undecorated, with plaster smoothed over the wood joins. There was also some textile remaining, presumably from the mummy who once was inside.

inside tawahibre

An interior view of the base of Tawahibre’s coffin

While the interior is undecorated, we know the same isn’t true for the exterior, based on a photo recovered awhile back in the Archives. After a bit more digging in Archives recently, we found even more detailed photographs of the coffin lid and base, taken sometime before they were put on exhibit back in the 1930s.

tawahibre front and back

Image from the Archives showing the front of the coffin lid and the back of the coffin base

Recovering old images like this is exciting because they potentially have a lot to tell us. In this case, this photograph is a good record of what the condition of the coffin was like soon after it was acquired by the museum. Like in the exhibit photograph I had recovered earlier, I could see that a lot of the damage we’re seeing on the coffin lid today was present then. But there was no way of knowing, until this week, how the current condition of the coffin base compares to the condition seen in this photograph.

And I have to tell you, I was a bit worried – until just a few days ago, all I could see of the coffin base was from these views:

Detail views of the proper right and proper left sides of the coffin lid and base, before treatment

Detail views of the proper right and proper left sides of the coffin lid and base, before treatment

Those large chunks of plaster and paint on the wood support below weren’t very promising. I had a sinking feeling that a lot of the paint and plaster on the back of the coffin base was unstable as well, and going to fall away when we tried to lift and flip it over.

The first step in getting the coffin base flipped over was to stabilize the plaster and paint on the inside and sides of the base, as much as possible. I carried out this work using the same methyl cellulose adhesive solution and fill material mixture as I have been using on the lid.

Then we did a test lift, to see how stable it felt, and to determine if we needed to temporarily stabilize any areas on the back before turning it over.

test liftThe test lift was encouraging, so we decided just to go for it!

How many conservators do you need to flip over a coffin base? Eight, it turns out.

flipping over1Fortunately, the procedure went smoothly, smoothly enough that we even allowed our Public Relations Coordinator Tom Stanley post a video of us turning the base over on the museum’s Instagram account.

Once we turned the base over, we were rewarded by being able to see that the back is still remarkably well-preserved, with very little changes from when that old photograph was taken:

Tawahibre's base in the 1920s (left) and today (right)

Tawahibre’s base in the 1920s (left) and today (right)

Can you spot the differences in these two photographs? I’ll post another copy of this image soon, circling the changes that have occurred.


Slowly, but surely

Sometimes when working on a large, complex project, it can be hard to see progress – once certain areas are addressed/stabilized I just start focusing on all of the other problems. In these cases, I find it really helpful to write about the work, to go through the photos I’ve taken so far, and to reflect on how far we’ve come. One of the more complex treatments we’re working on in the Artifact Lab is Tawahibre’s coffin.

The last time you saw Tawahibre on the blog, she was all tied up, Lilliputian-style.

Tawahibre capturedSince that last post, we actually have made quite a bit of progress, and have started realigning and filling areas where the gesso and smaller wood components have cracked and separated from the wood ground below.

One very precarious area has been a large section on the lower proper left side of the coffin – when the coffin came into the lab for treatment, this section was only just barely attached along the top, with the help of two wooden dowels as well. In addition to being just about ready to detach, this section was also very distorted and misaligned, with areas of the painted surface overlapping and abrading each other.

tawahibre PL detail BT with arrows

Before treatment detail of this large partially detached section. It was just barely attached along the top (indicated by red arrows) and by 2 wooden dowels (circled in green).

Here is a view of this section, before treatment, from above (the red arrows are just pointing out the area that I’m talking about, for clarity).

tawahibre PL detail overhead BT with arrowsAfter working to humidify and realign this area as much as possible, I prepared it for filling and stabilizing by lining the wood support below and the inside surface of the detached section as possible with Japanese tissue paper, adhered with methyl cellulose adhesive. The Japanese tissue paper will serve to make these fills more easily reversible in the future.

Tawahibre PL detail DT with arrows

Preparing this section for stabilization and filling. The red arrows are indicating the Japanese tissue paper used to line the inner surfaces of the coffin before filling.

To secure this section to the rest of the coffin, I applied a fill mixture between the large partially detached section and the wood support below. The fill mixture was made using 5% methyl cellulose adhesive in 1:1 water/ethanol bulked with a 1:1 ratio of alpha cellulose and 3M glass microballoons. The alpha cellulose and microballoons were chosen to create a lightweight, relatively dry, and easily moldable fill – they also make this mixture a bright white color. After applying the fill material, this section was again bound with the twill tape and ethafoam blocks to hold everything together while the fill dried.

Detail of this section after filling. Note-no straps are needed to hold it in place!!!

Detail of this section after filling.

And here is a detail showing this section from above – I think it makes a nice comparison with the before treatment shot from a similar angle, above.

Tawahibre PL detail above DT2So far this has been a successful course of treatment and we have filled several areas on the coffin. Our current goal is to get the lid stabilized enough so that we can separate it from the base, so that we can continue to work on both sections with better access to some of the very unstable, fragile areas.

Special thanks to my conservation colleagues for their help with brainstorming, problem-solving, and carrying out this treatment!