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.

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.

 

Wilfred or Wilfreda?

So, there has been some controversy over the fact that our mummy Wilfred is being referred to by a man’s name because there is some suspicion that this mummy may in fact be female!

Just before Thanksgiving, Dr. Janet Monge, Keeper and Curator-in-Charge of the Museum’s Physical Anthropology Section, along with colleagues Page Selinsky and Francesca Candilio, took at peek at the mummy and there was a hot debate over some of the features on the pelvis, but they all started leaning toward the conclusion that the mummy may be a woman.

The group huddled around the mummy. Photo by Nina Owczarek, copied from the Museum's Instagram account.

The group huddled around the mummy. Photo by Nina Owczarek, copied from the Museum’s Instagram feed.

The group felt like they needed to see the bones better. One of them (half-jokingly) asked if we could just lift the pelvis out. While we plan to take some new x-rays using our new digital radiography equipment, we have to do some work on the mummy in the lab first. But in the meantime, we can take a look at the x-rays taken in 1932 over at the Hospital of the University of Pennsylvania. The only notes from this old radiographic study say “adult”.

Radiograph of the chest area, showing the crossed arms, ribs, vertebrae.

Radiograph of the chest area, showing the crossed arms, ribs, vertebrae

Radiograph of the pelvis.

Radiograph of the pelvis

Radiograph of the feet.

Radiograph of the feet

Dr. Monge offered to share these images with her colleague Dr. Morrie Kricun, Emeritus Professor of Radiology, Hospital of the University of Pennsylvania. Dr. Kricun was able to manipulate the image of the pelvis to view it as it would look like if it was undisturbed.

Manipulated radiographic image of the mummy's pelvis

Manipulated radiographic image of the mummy’s pelvis

He’s also leaning toward female, but wants to do some additional imaging, which we plan to do soon. I promise to update the blog as soon as we do this! But for now, I feel like I may need to start calling this mummy Wilfreda.

 

Glowing in the dark: multispectral imaging and Egyptian blue

There is something I’ve mentioned before on this blog, but never actually shown, and that is the ability to “see” Egyptian blue on objects using multispectral imaging. On many objects Egyptian blue is very well-preserved, so there is no need for special examination techniques in order to spot it. But there are cases in which being able to accurately identify this pigment is important. Sometimes Egyptian blue deteriorates either by changing color (to green or black) or by becoming lost altogether, making it difficult to know which areas may have originally been blue, or if blue was used at all.

And then there are objects like this one:

Front view of the shabti box in normal lighting conditions

Front view of the shabti box in normal lighting conditions

You’ve seen it before, it’s our painted wooden shabti box. I have been working on the treatment of this box for awhile now, mostly to stabilize the flaking paint and varnish. And this thick, orange-yellow varnish, which we believe is original, and is pistacia resin, makes it difficult to see the painted surface, both the details and the colors. While I could see that there is some green and possibly blue paint on this box, between deterioration of the paint and/or pigment, and the thick application of pistacia resin, I couldn’t say for sure which areas may have originally been painted blue…until now…

Taking advantage of the fact that Egyptian blue has luminescent properties when illuminated with visible light and captured in infrared, we can detect where Egyptian blue was applied. And wow, look at these results:

Visible-induced IR luminescence image of the shabti box. Light source: SPEX Mini Crimescope with 600nm band-pass filter. Captured with a Nikon D5200 modified camera with an IR 87C filter.

Visible-induced IR luminescence image of the shabti box. Light source: SPEX Mini Crimescope with 600nm band pass filter. Captured with a Nikon D5200 modified camera with an IR 87C filter.

This is the same surface of the shabti box seen in the first photo, but zoomed in a bit, and taken under different lighting conditions and captured with a different camera. The areas that appear white are where Egyptian blue was applied. Because everything else pretty much disappears on the box in this image, to better visualize where the Egyptian blue is in relation to other details, we created a false-color image in Photoshop:

False color image of the shabti box. The areas painted with Egyptian blue appear red.

False color image of the shabti box. The areas painted with Egyptian blue appear red.

In this false color image, the areas that appear red are where the Egyptian blue was applied. It’s not perfect (you can see that the bands in the hair of the figure on the right don’t really show up) but we could play around with the photographs a bit to improve this.

We did this imaging on all surfaces of the box, and on the box lids. Here is a regular photo, a visible-induced IR luminescence photo, and a false color image of one of the box lids, also showing lots of Egyptian blue:

Shabti box lid, normal light

Shabti box lid, normal light

Visible-induced IR luminescence photograph

Visible-induced IR luminescence photograph (areas in white = Egyptian blue)

False color image (areas in red = Egyptian blue)

False color image (areas in red = Egyptian blue)

You can use any regular/visible light source to produce the luminescence, but in this case, we used our fancy-schmancy new Mini Crimescope, which was developed for forensic work, but is useful to us because it allows us to examine objects under specific wavelengths of UV and visible light. We found that using a peak emission 600nm light source worked best for the excitation of the Egyptian blue.

In order to “see” the luminescence, we have to capture images using a modified digital camera, with an 87C IR filter.

In summary, we’re having lots of fun with our new equipment, and finding that these Egyptian objects are perfect subjects for learning how to use the Crimescope and the modified camera, because they produce such great, dramatic images.

 

Views inside a painted wooden coffin

It is impossible not to see this object when you enter the Artifact Lab, as it’s front and center, and immediately impressive, due to its well-preserved painted details:

view of lab with coffin with arrowThis is the lower-half of a late New Kingdom painted wooden coffin, that recently came up to the Artifact Lab. Our visitors are always commenting on how vibrant the colors are, and that is mostly based on what they can see from the exterior. But the interior of this coffin is fully decorated, and arguably even more impressive, and I promised some people this week that I’d post photos of the interior soon. Here they are:

Overall view of the interior of the coffin from above

Overall view of the interior of the coffin from above

coffin right side

View of the right side

coffin left side

View of the left side

View of the interior, top of the coffin

View of the interior, top of the coffin

The only areas on the coffin that are not decorated are the exterior of the back, and both sides of the foot/base.

All in all, this coffin is in great condition, but it needs some treatment, including surface cleaning and stabilization of the wood and paint in some areas.

There are also a few mysterious things about it, in particular, these drilled holes in the back – what the heck are these all about?

There are 8 rows of holes drilled through the back of the coffin

There are 8 rows of holes drilled through the back of the coffin

Stay tuned as we investigate further.

 

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.

E12505_woodID

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.

More about our Predynastic mummy

Last year we posted some information about Bruce, our Predynastic mummy (and the oldest Egyptian mummy in the museum) here in the lab. Bruce has been on ongoing project, but he is often tucked toward the back of the lab unless we are actively working on him. While he’s often not front-and-center, when visitors enter the gallery and they catch a glimpse of him, they know that he’s special, even if they don’t know what he is, exactly.

Bruce on his cart, near the back of the lab, as viewed through the Artifact Lab windows.

Bruce, near the back of the lab, as viewed through the Artifact Lab windows.

As soon as he is spotted, I am often asked “what is that?” “is that a mummy?” and “what are you doing with him?”. In conservation, we are not always actively treating objects (or in this case, mummies); some of our projects involve close examination and study of objects (often referred to as technical studies). These technical studies may be a precursor to conservation treatment, but they may also be independent of treatment.

We are not currently carrying out conservation treatment on Bruce. Our focus at the moment is careful examination and some analysis, in consultation with other specialists. At the moment, we are focusing on trying to identify the type of animal hide that he’s wrapped in:

The red arrows are pointing out pieces of the animal skin bag wrapped around Bruce.

The red arrows are pointing out pieces of the animal skin bag wrapped around the mummy.

and also the animal hairs used to make the finely woven baskets included in his burial bundle:

E16229_basketsThese baskets are actually made of plant and animal fibers – the baskets are twined, and the passive elements (or warps) are made of plant fibers, while the active elements (wefts) are made of light and dark animal hairs. We know that the wefts are animal hairs based on our examination of these fibers using our polarized light microscope (PLM).

Views of the light-colored hair (left) and a cross-section of the hair (right) at 100X magnification

Views of the light-colored basketry fiber at 10X (upper right), at 50X (lower left), and a cross-section (lower right) at 200X magnification

Views of the darker hair (left) and a cross-section of the hair (right) at 100X magnification

Views of the darker basketry fiber at 10X (upper right), at 100 X (lower left), and a cross-section (lower right) at 200X magnification

Sometimes animal hair can be identified based on the features observed under a microscope, by comparing the unknown hairs to known reference samples. Some great animal hair ID sources on the web include this great resource on the FBI website and the Alaskan Fur ID website.

While we can clearly see that these fibers from the basket are animal hairs, we have not been able to identify them based on microscopy alone, so we are pursuing other analytical methods of identification, such as peptide mass fingerprinting (PMF). PMF uses a mass spectrometer to analyze the peptides in a proteinaceous sample, which can identify mammalian material to the species level using a micro-sized sample. Next week, I am attending a collagen identification workshop at Harvard, where I will learn more about PMF and its application to cultural artifacts.

We are excited by the possibilities this technique offers – being able to identify the skin(s) Bruce is wrapped in and the materials used to make the baskets found in his bundle will add to our understanding of very early technologies and funerary practices in Egypt. We will certainly share our findings as we learn more.