A closer look at one of our feathered friends

We have an ibis mummy in the lab, which is revealing itself to us in an unusual way.

Unlike most animal mummies in our collection, we can actually see the ibis’ remains – in this case, its feathers! It is unfortunate that the linen wrappings were damaged in the past, but this damage does provide a unique look under the bandages.

ibiswithfeathers

Ibis mummy, 97-121-19, from Thebes, Late Period (ca. 664-332 BCE).

While x-ray radiography revealed that there is indeed an ibis inside (the beak is a dead giveaway), the feathers provide further clues about this bird that was mummified approximately 2500 years ago.

Radiograph taken from the top down. Exposure information: 35kV, 5mA, 6 seconds. Image enhanced with flash! filter.

Radiograph taken from the top down. Exposure information: 35kV, 5mA, 6 seconds. Image enhanced with flash! filter.

When researching ibis mummies, I read again and again about the African Sacred ibis (Threskiornis aethiopicus) being mummified, but there were other types of ibis in Egypt, including the Glossy ibis (Plegadis falcinellus) and the Northern Bald ibis (Geronticus eremita). I don’t know if evidence has been found that these other types of ibis were mummified, but I do know that I shouldn’t immediately assume that this particular ibis mummy contains the remains of an African Sacred ibis.

So, let’s look at the feathers, and what we can learn from them. The feathers that are exposed appear to be contour feathers that may be part of one of the wings. There are a few completely detached feather fragments in this area, so I was able to take a closer look at one small fragment under the microscope.

ibisfeatherlabeled

Left: ibis feather 7.5X magnification. Right: ibis feather 50X magnification.

The most obvious feature to note, even without a microscope, is the coloration. This feather is white and black. The African Sacred ibis has a very beautiful, distinctive, black and white plumage, so in this case the color alone may be enough to identify species.

If we can’t rely on color, what else can we learn from this feather fragment? Well, we can see that it is part of a pennaceous (rather than plumulaceous, or downy) feather, the parts of which I’ve labeled in the above images. To take an even closer look at these elements, I used our polarizing light microscope and was able to see the tiny hooklets on the barbules, which “zip” the barbules, and therefore the barbs, together.

Ibis feather 100X magnification.

Ibis feather 100X magnification.

The barbules of feathers can be used for identification of species, but usually barbules from plumulaceous feathers are used, as they have a very different and distinct appearance. Unfortunately, I don’t have access to any plumulaceous feathers from this ibis mummy, so this may be as far as I can go at the moment. There are other researchers, both within the field of Egyptology, but mostly in ornithology, who have spent much more time looking at ibis feather structure than I have, and of course there is DNA research, so we may learn more in the future about this ibis mummy and its feathers.

I have a special place in my heart for birds and feathers, since before coming to the Penn Museum, I worked on an extensive project on feather coloration as part of a collaborative research effort between UCLA and the Getty Conservation Institute. Click on the links below to find out more about this work:

A Collaborative Study of California Featherwork

California Featherwork: Considerations for Examination and Preservation

And to learn more about feather structure, start by following this link: The Cornell Lab of Ornithology: All About Birds: Feather Structure

Spring cleaning?

It may be a little early for spring cleaning, but no matter what time of the year, there is not much that I find more satisfying than a good, deep clean (on a grimy artifact). Last week, Tom Stanley (the museum’s Public Relations/Social Media Coordinator) posted this image on the museum’s Facebook page, which shows some cleaning in progress on an Egyptian painted wooden coffin here in the Artifact Lab:

coffin board cleaningHe also posted this on our Instagram page.

Here is a before treatment image of the coffin board (which is in 3 separate fragments):

E12617A-C, boards from a painted wooden coffin

E12617A-C, boards from a painted wooden coffin

While Tom was in the lab taking photos, I promised him that I’d put some additional information about this project on the blog. I thought this would be a great opportunity to take another video with our binocular microscope, kind of like the video I captured of the paint consolidation on the shabti figures I worked on awhile ago.

To see the process of how we go from

————————–this————————–to————————–this————————-

corner before after

click on the link below.

Cleaning an Egyptian painted wooden coffin from Molly Gleeson on Vimeo.

In the video, you’ll see (at 7.5X magnification) that I first used a soft-bristled brush to remove loose sediment and dust from the surface, by brushing directly into the nozzle of a variable suction HEPA-filtered vacuum. Then I used a cosmetic sponge to further, gently, lift away grime from the surface. Finally, I used a kneaded rubber eraser to remove the grime that is more embedded in the painted surface.

Okay, so I’ll admit that this may not be as cool as the video of Conservator Tessa de Alarcon laser cleaning a stone table from Ur (this one is hard to top), but it’s pretty gratifying nonetheless.

I’m currently trying to learn more about this object too, by checking into our museum records. I’ll keep you posted.

Multispectral imaging of Wilfred/a’s cartonnage

E12328B_4viewsWhat you see above are 4 different images of our mummy Wilfred/a’s cartonnage. Each image represents a different way of looking at the cartonnage, and assists us in better understanding this object. But what are we seeing in these images, and how did we produce them? (If you have been following this blog, or our museum blog, these types of images may be familiar to you, since we have used these techniques to look at other objects, including a painted wooden shabti box. But every object is different, and in this case, I’ve learned something new that I’ve never seen before, so read on to learn more!)

Let’s start with the image in the upper left – this is easy.

E12328B_visible01_compressed

Visible image. Captured with a Nikon D5200, modified by replacing the hot mirror filter with a glass custom full spectrum filter, with a B+W UV-IR-cut filter & incandescent photo light source.

This is a photograph taken in normal (visible) light with a digital camera. This image represents what you see when you look at the object here in the Artifact Lab. We see that the surface of the cartonnage has a design painted in many different colors, and that there are some residues on the painted surface in areas. There is a lot that we can learn about this object just by looking at it in visible light, but what we cannot do is confidently identify the pigments used. So in this case, multispectral imaging comes in very handy. Let’s take a look at the next image.

E12328B_IR01_compressed

Visible induced IR luminescence image. Captured with Nikon D5200 modified full spectrum camera, #87C filter, Crimescope 600nm light source.

This is an image of the exact same view of the object, but it was captured using our modified digital camera with a #87C IR filter, using our SPEX Mimi Crimescope with the 600nm filter as a light source. With this technique, we can clearly identify that Egyptian blue was used in the areas that appear bright white, because these areas are showing visible-induced IR luminescence (in other words, they emit infrared light when excited with visible light). No other pigment used by the ancient Egyptians has this property, so we can say with certainty that these areas are painted with Egyptian blue. To better visualize these areas (since the rest of the image is nearly black) we can use the image captured in visible light and the above image to create a false color image.

False color image of the cartonnage created in Photoshop, where the areas painted with Egyptian blue appear red.

False color image of the cartonnage created in Photoshop, where the areas painted with Egyptian blue appear red.

The false color image shows us the luminescent (Egyptian blue) areas in red. If you look closely, you’ll be able to see that the red areas are slightly shifted, due to the fact that we probably bumped the camera in between shots. But you get the idea.

Finally, I wanted to see what we could learn about the cartonnage by looking at it under other wavelengths of light with the Crimescope. I was expecting that we’d probably be able to better visualize the old adhesive used to join the cartonnage fragments in the past, and maybe better understand the residues on the surface. But when we looked at it with the 300-400nm filter (with a peak emission of 365nm), this is what we saw:

UV visible fluorescence image, captured with a Nikon D5200 modified full spectrum camera with B+W UV-IR-cut filter, using the Mini Crimescope 300-400nm filter.

UV visible fluorescence image. Captured with a Nikon D5200 modified full spectrum camera with B+W UV-IR-cut filter, using the Mini Crimescope 300-400nm filter.

In this image, the areas that stand out the most are the areas fluorescing a bright orange-pink color, which appear pink in visible light. I had never seen this before and wasn’t exactly sure what this meant, but after looking into it a bit, I believe that this fluorescence indicates that the pink areas were painted with madder, a dyestuff obtained from the roots of the madder plant. Madder has been identified as being used in ancient Egypt to create pink pigments for painting, and is known for having a characteristic pinkish-orange UV fluorescence, which is how I would characterize what we’re seeing in the above image. There are other ways we could try to confirm this, but this was an exciting, and unexpected observation!

* Special thanks to conservation intern Yan Ling and Conservator Tessa de Alarcon for their help with capturing and processing these images.

Conservation at the Penn Museum: the next generation

Our department temporarily gained a member last week, when aspiring conservator Jessica Schwartz returned to spend an afternoon with us.

Conservator Tessa de Alarcon shows Jessica an RTI (reflectance transformation imaging) file of a seal impression from Ur.

Conservator Tessa de Alarcon shows Jessica an RTI (reflectance transformation imaging) file of a fragment of a jar stopper from Ur. The seal impression is so worn, and RTI revealed that it actually has 2 different impressions on it.

Jessie, a 6th-grader from Atlanta, has been interested in archaeology for as long as she can remember, but after seeing us working In the Artifact Lab two summers ago, she redirected her energy to pursuing archaeological conservation. There aren’t many opportunities for 12-year olds to gain experience in conservation, so we thought that if she spent some time with us, she’d get a taste of what we do on a day-to-day basis.

The first time she worked with us, last summer, we spent some time looking at our Predynastic mummy Bruce, using our microscopes to identify materials, and making scarab amulet impressions, and she wrote about all of this on the blog, which you can find by following this link.

Last week she came for a return visit (her family was here for the opening of our new exhibition, Beneath the Surface: Life, Death, & Gold in Ancient Panama) and she kept pace with all of the activities of the afternoon, including discussing my ongoing treatment of Pinahsi, a New Kingdom mummy (she had a good eye for picking out where I had repaired the textile shroud!) and reviewing radiographs of some of our animal mummies.

Jar of dirty cotton swab tips

Jar of dirty cotton swab tips

One of the first questions Jessica asked me when she came into the lab was, “what is that container full of little bits of cotton for?”. I’m so glad she asked (it’s a cotton swab disposal jar), because it gave me the idea to teach her one of the most important skills for a conservator to have – rolling your own cotton swab! We make our own swabs for cleaning objects because it allows us to have more control over the size and shape of the swab and the amount of cotton, and it’s also a lot cheaper. Jessica was so pleased with learning this new technique – I told her it would take her far!

 

Jessie with a successfully-rolled swab

Jessie with a successfully-rolled swab

After working in the Artifact Lab for a bit, we went downstairs to our new digital x-ray lab* to review some animal mummy x-radiographs. I x-rayed the animal mummies just before Jessie’s visit, so this was an opportunity for us to learn from the radiographs together. (*We are super excited about our new digital x-radiography equipment and we are just starting to use it to examine objects in our collection. I have been meaning to write a post just about the equipment and some of the things it has already allowed us to do, so look for this in the near future.)

One of the mummies we x-rayed was this ibis mummy, which our graduate intern
Alexis North treated over the summer. As far as we know, this mummy had never been x-rayed before, so we really had no idea what the radiograph would reveal. Here are the 2 views we captured:

X-ray image taken from the top down. Exposure information: 30kV, 1mA, 6 seconds

X-radiograph taken from the top down. Exposure information: 30kV, 1mA, 6 seconds. Image enhanced with flash! filter.

 

X-ray image taken from the side. Exposure information: 35 kV, 1mA, 6 seconds

X-radiograph taken from the side. Exposure information: 35 kV, 1mA, 6 seconds. Image enhanced with flash! filter.

Both views clearly show that there are bird remains inside, and the side view shows the characteristic long, curved beak of the ibis really well. The radiographs also show the textile wrappings and even the materials in the storage support! But focusing on the bird remains, they seemed a little…sparse. So we consulted with the museum’s zooarchaeologist and teaching specialist Dr. Kate Moore. She brought us into her lab and showed us a complete heron skeleton (she doesn’t have an ibis skeleton, but a heron is very comparable in terms of size and the shape of the bones).

TessaJessieKate

Dr. Kate Moore (far right) shows Tessa and Jessica a heron skeleton

Here is the complete skeleton, which Kate piled up on the table so that we could get a sense of how much volume those bones take up. After seeing these bones, we took another look at the x-radiograph, and realized that our ibis mummy only contained about half the bones of a complete skeleton (for starters, the pelvis is missing completely).

Heron bones

Heron bones with sharpie marker used for scale.

As you can see, we had a full afternoon, and we learned a lot together. Jessie had to fly back to Atlanta today to turn her attention back to her current full-time job, being a sixth grader, but we look forward to her next visit. While college, and conservation graduate school, are a bit far off in the future, we can already see that if Jessie ultimately decides to pursue conservation, she’s going to excel!

 

Continuing the treatment of Pinahsi

Just a quick update on the treatment of our mummy Pinahsi. I worked on him all day today and made some good progress. My efforts were focused on encapsulating the detaching, tearing, very fragile linen on the sides and underneath the mummy’s body. Just as I did with the feet, I used nylon bobbinett, toned with acrylic paint where necessary, to protect these damaged areas. In some places, I was able to wrap the bobbinett around the mummy and stitch it to itself, but in other places, I decided to adhere the bobbinett to discrete areas on the mummy, using Japanese tissue paper and methyl cellulose adhesive.

Here is a shot of the treatment in progress, showing the bobbinnet with small pieces of paper attached to one edge, which will be used to attach the bobbinett to the mummy. The edge of the bobbinett that will be visible is painted to match the linen.

Getting ready to attach the nylon bobbinett to the underside of the mummy. The edge of the bobbinett that will be visible is painted to match the linen, and there are small pieces of paper adhered to the edge, which will be used to attach the bobbinett to the linen.

Getting ready to attach the nylon bobbinett to the underside of the mummy.

And here are some before and after shots, showing areas that I’ve encapsulated with the netting:

A detail of the right side of the mummy before and after attaching the nylon bobbinett.

Details of the right side of the mummy before and after attaching the nylon bobbinett.

Details of the left side, before and after treatment.

Details of the left side, before and after treatment.

Tomorrow I’ll move on to some more challenging areas that I’ve saved for last! I’m hoping to “wrap up” this treatment sometime next week. Wish me luck!

 

What’s the deal with Pinahsi’s feet?

I think we can all agree that our mummy Pinahsi’s feet need a little TLC.

A detail of Pinahsi's feet

A detail of Pinahsi’s feet before treatment

A long time ago, the wrappings around his feet were damaged, exposing his toes. His toes are very well-preserved, despite the fact that 2 toes on the left foot are missing.

The second toe on each of his feet is lifted away from the others, and we have been debating whether this distortion was caused by the feet being tightly wrapped during mummification (which they were) or whether this distortion was caused by a condition Pinahsi had during his lifetime (I’m leaning toward the second possibility).

A view of the toes from the side

A view of the toes from the side

In any case, I thought it was about time his feet received a little bit of attention.

While I can’t do anything for those crooked toes, I am able to address the damaged linen and resin-coated linen wrappings around his feet. I repaired a few tears in the linen with Japanese tissue paper and 5% methyl cellulose, and then I wrapped the feet in the most damaged area with nylon bobbinett, toned to match the surrounding material with acrylic paint. Visually, the difference is subtle, but I can assure you that the feet are going to be much less prone to continued deterioration now that the damaged linen is stabilized and protected.

Details of the feet before (left) and after (right) treatment.

Details of the feet before (left) and after (right) treatment.

The back of the feet before (left) and after (right) treatment.

The bottom of the feet before (left) and after (right) treatment.

In the images above, you can probably pick out the band of bobbinett – it’s more visible on the bottom than on the top. When you get really close to the feet, the bobbinett is really obvious.

Detail of the top of the feet, showing the bobbinett overlay.

Detail of the top of the feet, showing the bobbinett overlay.

In our efforts to strike this balance between making our work more or less invisible, while also wanting to make sure that the new materials we add are easily distinguished from the original, we often refer to the “six-foot/six-inch” rule – at six feet, our work is not obvious but at six inches you will be able to see it. In this case, it is my hope that when the mummy is on display and viewed through the display case, the bobbinett I add will not be distracting to the viewer, but when you look for it, you’ll be able to pick it out.

Now I’m about to tackle the damaged linen on Pinahsi’s body. Just yesterday, we lifted Pinahsi up onto some Ethafoam support blocks, to allow me to access the damaged areas on the mummy’s sides and back.

Pinahsi raised up on Ethafoam blocks.

Pinahsi raised up on Ethafoam blocks.

I will provide updates as I complete more of the treatment!

 

Examination and treatment of Wilfred/a

We still haven’t gotten to the bottom of the question of whether our mummy Wilfred is indeed Wilfred or is instead Wilfreda, because there have been a few things to take care of first. In the meantime, I am referring to the mummy as Wilfred/a. Hopefully this person would not be offended by the ambiguity, but we hope to clear this up soon by x-raying the mummy using our new digital x-ray system. Before we can do this, I have been working to stabilize the remains enough to allow them to be moved safely down to our x-ray room. In the process of stabilizing the remains, I have made some observations.

The exposed remains on the upper part of the body, while very fragile and disarticulated, are remarkably well-preserved in areas. The preservation of the hands and arms is particularly notable – the fingernails are intact on the left hand, and it is clear that the arms and hands were wrapped separately with linen as part of the mummification process, due to the presence of linen and impressions of linen on the skin.

A detail of the left hand and arm. Note the presence of fingernails, and the linen and linen impressions, marked on the photo with yellow and red arrows.

A detail of the left hand and arm. Note the presence of fingernails, and the linen and linen impressions, marked on the photo with yellow and red arrows.

Unfortunately, we can also see that there has been damage to the right hand since the 1932 x-rays were taken (Wilfred/a, along with many other mummies in our collection, was x-rayed in 1932 by Dr. J.G. Cohen at the Graduate Hospital). In the old radiograph, it is evident that on the right hand, the thumb is intact, and at least most of the hand and fingers are also intact (the hand is partially cut off on the image). Today, we’re missing the thumb, all of the fingers, and part of the hand – only 3 of the metacarpal bones remain.

Left image: 1932 radiograph, showing arms crossed and right hand intact. Right image: 2015 photograph, showing damage to right hand.

Left image: 1932 radiograph, showing arms crossed and right hand intact. Right image: 2015 photograph, showing damage to right hand.

In my examination of the remains, I did not locate any detached elements from the right hand, but it doesn’t meant that they’re not in there somewhere! We may locate them once we x-ray the remains again.

Also of note is that the arms are crossed over the chest, right over left. From what I have read, the crossed arm position is generally not seen until the New Kingdom, when it is reserved for royalty, until about 600 BCE or later. We think that Wilfred/a dates to the Ptolemaic or Roman period, based on the style of the intact wrappings around the legs.

This mummy was elaborate wrapped with narrow strips of linen, creating a rhomboid pattern.

Wilfred/a’s wrappings are intact from the pelvis down, with narrow strips of linen creating an elaborate rhomboid pattern.

Because Wilfred/a likely dates to this Graeco/Roman period, the arms crossed over the chest do not indicate royalty, necessarily, and may have been to emulate the pose of Osiris (see this article for more information).

Once these observations were documented, I started in on the treatment. Since there are no immediate plans to exhibit Wilfred/a’s remains, I took some measures to stabilize them for the move down to the x-ray room and for eventual return to storage. If we ever do decide to exhibit them, the conservation work to prepare them for display will be much more straightforward now that some of the initial work has been carried out.

After removing Wilfred/a from the mattress (with a little help from my colleagues), I carefully removed all fully detached material and bagged it according to material type. I lightly cleaned the surface of the exposed arms and the intact wrappings on the legs and feet, recovering some insect remains and remnants of old packing materials (like cotton and wood shavings) in the process. I then wrapped the mummy in Tyvek and bolstered the sides of the chest area with pillows made from Tyvek and polyester batting. Wilfred/a is now ready to move onto a rigid support, which we plan to make from archival honeycomb board specially purchased for this project.

Wilfred/a, pictured here after treatment, is now almost ready to be moved down to our x-ray room.

Wilfred/a, pictured here after treatment, is now almost ready to be moved down to our x-ray room.

 

Wilfred/a’s cartonnage

While we prepare our mummy Wilfred/a to be x-rayed, we are simultaneously working on fragments of cartonnage that may belong to the him/her.

Cartonnage fragments before treatment, in no particular arrangement or orientation

Cartonnage fragments before treatment, in no particular arrangement or orientation

There are 35 pieces, some of which are assemblages of multiple fragments mended together, plus some very small fragments in a ziploc bag.

The cartonnage consists of 2 layers of linen adhered together, with a fine plaster coating on one side, which is painted, and a thinner, more coarse layer of plaster on the other side. Here is a magnified image of one of the fragments, and an image of it in cross-section:

The painted side of one fragment of cartonnage (left) and the same fragment in cross-section (right), 7.5X magnification

The painted side of one fragment of cartonnage (left) and the same fragment in cross-section (right), 7.5X magnification

It is unclear what these fragments originally belonged to. They definitely do not make up an entire object, and they are mostly flat. We can see that there are at least 3 figures depicted in the painted decoration, but we’re still in the process of trying to piece together the rest of the design, and trying to figure out which pieces join together.

Pre-program intern Yan Ling examines the cartonnage fragments with the aid of an optivisor.

Pre-program intern Yan Ling examines the cartonnage fragments with the aid of an optivisor.

Yan Ling, our pre-program intern and an art conservation undergraduate from the University of Delaware, is helping me document the fragments. As part of our examination process, we will be looking at the fragments with our Mini Crimescope, and we’ll post anything interesting that we find on here soon.

 

Another new mummy in the lab

We have another new mummy in the lab, and we may actually know this one’s name (unlike Wilfred, or Wilfreda, who has that nickname for some unknown reason).

E16221, Mummified man from Abydos

E16221, Mummified man from Abydos

According to our database, and the original catalog card, this is a mummified man named Pinahsi. He was excavated in 1901-02 from Abydos by Sir W. M. Flinders Petrie, and dates to the 19th Dynasty. The mummy doesn’t appear to be mentioned in Petrie’s Abydos publications, but there is a note on the catalog card that he may be related to the owner of the stela “Pa-asi” which is mentioned in his publication, and was found by Petrie in the Osiris temple at Abydos. I’m uncertain how this stela and the mummy are linked, but I’m hoping that this may become more clear once we access related information in our Archives.

Pinahsi has been on display in our Mummy Gallery since 1990, and we removed him from display for some much-needed conservation treatment. When the mummy came into the lab, I guessed that he dated to the New Kingdom, because the wrappings on the head look nearly identical to those on this disembodied head (below) that we worked on in the lab last year.

E2162, New Kingdom (22nd Dynasty) mummy head

E2162, New Kingdom (22nd Dynasty) mummy head

Fortunately for Pinahsi, we have his whole body, which is wrapped in many layers of linen, ranging from coarser to very fine weave, and some of the uppermost layers are impregnated with resin (just as we see on the mummy head above). Pinahsi is very heavy, which indicates just how much of this resin was used in the process of mummifying him.

Pinahsi

Detail of the head and upper half of Pinahsi’s body, showing resin-soaked linen around the head, and severe insect damage on the linen over the chest

We’ll be working on stabilizing his linen wrappings in areas where they are torn and detaching, and we will make a new support for him before he returns to exhibit.

Pinahsitoes

Detail of Pinahsi’s feet. The linen is badly damaged in this area, exposing the toes. One visitor remarked yesterday that it looked like he was trying to wriggle out of his wrappings!

We will also x-ray his remains again; they were x-rayed back in the 1930s and you can see one of these images by clicking here, which shows that Pinahsi has amulets included in his wrappings. Hopefully with our new digital x-radiography equipment, we’ll be able to capture even better images of these amulets and his remains.

To catch a glimpse of Pinahsi before he goes back on display, visit the Artifact Lab – every day the museum is open over the holiday, we will have someone working in the lab between the open window hours, which are 11:15-11:45 and 2:00-2:30 Tuesday – Friday, and 12:30-1:00 and 3:30-4:00 Saturday and Sunday.

 

Analysis of the shabti box varnish

This is a long overdue post about the varnish on our beloved shabti box (in my last post I referred to the box as troubled…I’ve developed a tiny bit of a love-hate relationship with it, which I’m only now admitting).

A detail of the shabti box before treatment, showing the actively flaking and fractured orange-yellow varnish

A detail of the shabti box before treatment, showing the actively flaking and fractured orange-yellow varnish

Anyway, I’ve briefly mentioned that we believe that the varnish on our shabti box is a pistacia resin, but how did we come to this conclusion? I started out by doing some research into similar objects, and into painted wood from the New Kingdom in general. As I mentioned in a previous post, we know that some painted wooden objects were varnished with pistacia resin during this time period, and these varnishes often look like the coating we see on our shabti box. But there were some things about the coating, including the fact that it was actively flaking, and the fact that there are areas on the box where the paint is lost and where the coating extends over the loss onto the gesso below, which is strange.

In order to start characterizing the coating, I looked at the box under different light sources and did a microchemical spot test, all described here. All roads were leading toward the conclusion that the coating is pistacia resin, but since we had so many available samples (i.e. detached pieces of the varnish) I wanted to investigate further.

First, we turned to a resource that we have in-house: Fourier transform infrared spectroscopy, or FT-IR. FT-IR is a method of infrared spectroscopy, where IR radiation is passed through a sample, and some of the radiation is absorbed and some of it is passed through or transmitted. A spectrum is produced that represents the molecular absorption and transmission, which is unique to that material. I collected samples of detached varnish from the shabti box and from one of the shabti figures, and passed them along to Tessa de Alarcon, a conservator in our department, and consulting scholar Dr. Gretchen Hall. Here is what the spectra look like for each:

FT-IR spectra for samples of varnish from the shabti (top) and the shabti box (bottom).

FT-IR spectra for samples of varnish from the shabti (top) and the shabti box (bottom). The characteristic peaks are labeled on the top spectrum.

They look virtually identical, which confirms that the varnish on the box is the same as the varnish on the shabtis.

Dr. Hall then compared the spectrum for the shabti box sample to spectra for mastic (Pistacia lenticus) and terebinth (Pistacia terebinthus), both pistacia resins.

Spectra for (from top to bottom): the shabti box sample, a sample of terebinth, a sample of mastic from Chios purchased in Athens, and a sample of mastic from Kremer Pigments (the Kremer Pigment mastic sample spectrum was found in the IRUG database). IRUG = Infrared and Raman Users Group

Spectra for (from top to bottom): the shabti box sample, a sample of terebinth collected from the Uluburun shipwreck, a sample of mastic from Chios purchased in Athens, and a sample of mastic from Kremer Pigments Inc. (the comparative spectra were found in the IRUG database, IRUG = Infrared and Raman Users Group)

They all look very similar, with characteristic resinous acid peaks that occur between 1700 & 1720 cm-1 (carbonyl stretching) & the acid OH stretching that occurs ~1460 cm-1.

In order to see if we could classify the shabti box resin even further, Dr. Hall took a sample to Dr. Chris Petersen, Affiliated Associate Professor in the Winterthur/University of Delaware Program in Art Conservation (WUDPAC), where they analyzed it using Gas Chromatography-Mass Spectrometry (GC-MS). GC-MS is a technique that combines 2 methods of analysis, and in conservation we use it to analyze organic compounds.

Dr. Hall and Dr. Petersen ran the sample and here is what the GC-MS chromatogram looks like:

L-55-23A_GCMSlabeled2Dr. Petersen labeled the peaks and included their structures. The structures are consistent with pistacia resin, either mastic or terebinth. They did identify a peak for 28-norolean-17-en-3-one (#3 above), characteristic of heated pistacia resin, which could indicate that the resin was heated before application (which would have turned it from clear to a yellowed varnish). We cannot be certain what color the varnish was when it was first applied, but the analysis does confirm the fact that the shabti box and the shabtis all have aged pistacia resin coatings.

We are grateful to both Dr. Hall and Dr. Petersen for their work on this analysis!