X-ray excursion

If you stopped by the Artifact Lab this week, you might have noticed that our falcon mummy is no longer on display, and this sign in its place:

falcon signAs indicated on the sign, the falcon has been removed for x-radiography. This mummy has never been x-rayed before, and we’re interested in using this imaging technology to learn how it was made and if there are any falcon remains inside!

Along with the falcon, we’re also going to be x-raying/CT-scanning our (possibly headless) cat mummy, the wooden statue heads, and several other pieces.

We do not have the ability to x-ray and CT-scan objects here in the museum, so we will be taking these selected pieces for a little trip tomorrow. In preparation for their travels, they are securely packed, and ready for this exciting excursion!

The falcon mummy is secured inside its storage support and packed into a larger box for travel.

The falcon mummy is secured inside its storage support and packed into a larger box for travel.

We will update the blog with our findings soon after we return.

 

Let’s focus on the eyes.

eye

In a former post we saw that a conservator has to gather clues about an object’s past and do a lot of bibliographical research. Now let’s talk about the materials themselves and the amazing eyes of these two wooden heads.

During these last few weeks we have been busy trying to identify the materials used to make the eyes; we knew that there were three of them, one for the outer line (or eyelid), a second for the white part, and the third one for the black pupil. We first observed the eyes under a binocular microscope, which is the easiest way for a conservator to have a close look at an object.

Leica Picture

Wood is missing around the eyes, but it allows us to see more of the metal !

Leica Picture

Here is a pink-golden layer of copper that we can identify through the corrosion layers.

 

The material used for the eyelids was immediately identified as a copper alloy because of the green corrosion products observed on the surface. Moreover we can see the metallic pink-golden surface of the copper here and there. However, the metal could have also been silver with some copper impurities; indeed when two metals are combined or in contact with each other in a burial environment, the less precious metal preferentially corrodes (also called galvanic corrosion).

To know more about the chemical composition of this alloy, we carried out X-ray fluorescence analysis (XRF), with the portable XRF device of the Lab.

Here are what the results look like:

E17911 - eye - bluefilter

Those peaks indicate what kind of elements we have in the metal. We learned that this is an arsenic-copper alloy, which is well-known for Egyptian artifacts. The other elements can be impurities in the metal or due to the burial environment of the objects.

Concerning the white material, the first thing we observed under the microscope was the lines in the material.

Leica Picture

Some detail of the lines.

IC800516

A clue for us was that we don’t see the lines across the entire surface, as we can see on the picture on the right (near the upper part of the pupil).

We first wondered if these lines indicated elephant ivory, since elephant ivory has unique features called Schreger lines. However, the lines in the whites of the eyes do not look like Schreger lines, which look more like cross-hatching. That’s why we then thought about tool marks; indeed, the Egyptian sometimes marked the material they used to make the white of inlaid eyes, to make them look more realistic. We quickly abandoned this theory because the pattern on the eyes is too regular and not spread across the entire surface.

So we returned to the idea that the material might be ivory, but what kind of ivory? We were lucky that our department recently acquired a complete set of ivory samples, so we could compare directly. It turned out that our eyes are made of hippo ivory. XRF analysis also revealed that the white is composed of calcium, which is coherent for ivory.

ivory

This is elephant ivory.

 

IC800527 - Copy

Here is an example of what hippo ivory looks like, with the entire surface covered with lines.

IC800522

Here is an area of the hippo ivory where we can see the limit between the lines and a smooth part.

Concerning the material used to make the black of the eyes, a few paths could be followed. According to the literature, Egyptians used obsidian, glass with a black substance on the back, or other black materials for the inlaid eye pupils. The microscopic observation of the wooden statue eyes revealed that the black material is translucent with tiny bubbles. This structure could indicate obsidian, which is a natural glass. Moreover, the Penn Museum has several spare eyes in storage; comparison with these known references confirmed that the pupils of the wooden heads are indeed made from obsidian.

Leica Picture

We will know more about the structure of the eyes by next week, since this Friday the heads are going to be X-rayed and CT-scanned !

 

First step for the heads

Last week I introduced you to two wooden statue heads that I’m working on and promised to share the step by step process of their conservation.

laura blog 2 image3

A first step in understanding these objects is gathering information about their past. As we said in the previous post, they are from Dendera and were discovered in 1898. The other questions were: Who discovered them? How and when did they arrive in Philadelphia? And more…

To address these questions, the best place to begin is the Museum Archives. I first checked Clarence Fisher’s field notebooks, since we know that he excavated in Dendera for the museum from 1915-1918, continuing the work begun by Charles Rosher and Flinders Petrie. An afternoon looking at (all!) of his notebooks revealed no leads. The other possibility was to refer to Petrie’s own field records; and here I found reference to the heads, or more precisely the “statuettes”, noted in his field notebook.

This page notes the “2 statuettes” at the foot of the coffin.
From Petrie Notebook n.15, p.30, courtesy and copyright of the Petrie Museum of Egyptian Archaeology, UCL.

That mystery solved, we moved onto the next one. Included in the storage drawer with the wooden heads, we found a note indicating “2 wooden statuettes nearly consumed by white ants”.

laura blog 2 image2After a little more digging, I found that this was a quote from Petrie’s publication about Dendera, on p.10, paragraph 2…and the rest is still meaningless to us! In this publication Petrie indicates that the heads came from a secondary burial, belonging to a woman, under Adu II’s own funerary chamber.

Moreover, it unveiled a new clue: Petrie wrote that he discovered “statuettes” and not only their heads. That could imply the fact that they were still complete statues at the time of the excavation. It is possible that they were in such a poor condition that the archaeologist left the bodies and only took the heads. We definitely do not have any more parts of these statues in our collection – after checking, no “spare bodies” are registered in the Egyptian storerooms of the Penn Museum.

All of this may seem to be only details but it is essential information for a conservator: the fact that W.M.F. Petrie discovered the heads is highly interesting, because he most likely treated them in the field. He published a book where he explains his practical way of applying a “first-aid” treatment to damaged artifacts (Methods and aims in Archaeology, 1904) which may provide critical information for us! Indeed, knowing this will allow the conservator to be aware of what kind of material was added to the original object and how to deal with it.

My investigation into these old treatment materials will be the topic of a post to come!

 

About two wooden Egyptian heads…

“You have a wonderful job!” It’s a sentence that a conservator often hears. But what is really this incredible job? I propose to you to have a closer look at what a conservator usually does by following step by step the conservation of two artifacts recently arrived in the Artifact Lab.

Laura blogpost1Not really the glamorous objects you imagine when you think about Ancient Egypt, right? But they can reveal so many things to us.

Let’s begin with all what we knew when they arrived in the Lab: these artifacts are two Egyptian wooden statue heads. They bear remains of polychromy (blue and red painting) and have inlaid eyes. In their storage drawer were three labels: one quoting a publication about Dendera (the place where they were excavated) describing the heads, and two others mentioning a previous treatment in 1965 with an adhesive called Vinylite.  Other information about these objects came from our curators, who knew that the heads are from the site of Dendera, more precisely the mastaba of Adu II, excavated by Flinders Petrie, a famous British archaeologist. Moreover, the heads are from the Sixth dynasty (2374-2140 BCE). That’s all we knew about those two heads before beginning our work !

Let’s have a closer look at them…

Left: one of the wooden heads viewed in profile Right: a front view of the other wooden head

Left: one of the wooden heads viewed in profile.  Right: a front view of the other wooden head.

A long quest is ahead and we’re only starting to think about an appropriate conservation treatment. Indeed, before any scalpel reaches their surface, we need to gather as much information as possible about the artifacts. Stay tuned to hear more about our discoveries and the decisions that we make based on what we learn.

 

Examinations of a baby boy mummy

I think it’s about time we introduce you to a special occupant of the Artifact Lab.

This baby boy mummy, who dates to the Third Intermediate Period (1075-656 BCE), has been in our collection since 1898, when he was donated to the museum by Dr. Henry Shurtleff.

Photograph of the baby boy mummy from the museum Archives

Photograph of the baby boy mummy ca. 1930

In the University’s 1898-1899 Annual Report of the Provost to the Board of Trustees, it states that Dr. Shurtleff presented the infant mummy to the museum on Christmas Day, as an “admirably preserved specimen and an interesting pathological subject”.

It seems that this mummy came into the collection unwrapped – he only has small amounts of textile preserved on his body (and there is currently no evidence that the cloth partially covering his body in the image above is related to his remains, but this remains to be determined). While the fact that he is unwrapped is unfortunate, it allows us to see how well preserved his remains are and evidence of how his body was mummified, including evisceration through an incision on the left side of his torso.

The open incision on the left side of his body reveals a mostly empty body cavity, containing small bundles of linen.

The open incision on the left side of his body reveals a mostly empty body cavity, containing small bundles of linen.

A CT scan in 2009 further reveals how this boy’s body was mummified, and also reveals damage not visible from the exterior. For example, it is clear that his brain was removed, likely through the nose (but due to the small side of his nasal bones it is not possible to see evidence of this). The scan also reveals a large hole in the left lower side of his skull, and the piece of missing bone resting inside his skull.

Two CT still images show the child mummy's skull with a piece of bone resting inside the cranium (left) and the hole on the lower left side (right).

Two CT still images show the child mummy’s skull with a piece of bone resting inside the cranium (left) and the hole created as a result of this loss (right).

Oddly, this damage to his skull is not visible from the exterior, but it may be the result of trauma. His cause of death has still not been determined, but this damage may provide a clue.

The information from the CT scan tells us that this child was less than 2 years of age when he died, based on the fact that his fontanelle (the soft spot) is still open, and also on the development of his teeth.

The open fontanelle on the top of the baby's head is indicated in these 2 images with blue arrows.

The open fontanelle on the top of the baby’s head is indicated in these 2 images with blue arrows.

The excellent preservation of his body is not the only remarkable thing about this baby boy. While examining his remains, we noticed traces of a green substance in areas, including on his face and fingers.

A detail of the green substance under the boy's right eye (left) and an overall view of the boy's face, highlighting the locations of the green substance in green (right)

Left: A detail of the green substance under the boy’s right eye. Right: An overall view of the boy’s face, highlighting the locations of the green substance in a brighter green color.

This substance resembles copper corrosion, and it may either be corrosion from copper that was once in contact with his body (during burial), or may be traces of a green copper-based pigment. How do we know this green substance is copper-based? We tested it with our portable x-ray fluorescence analyzer, which showed high peaks for copper in these areas.

While we’re still working to interpret some of this information, I can tell you one thing for certain: this baby boy mummy sure is special. And if you visit the lab, you just might catch a glimpse of him.

 

Losing it and faking it: investigations into our animal mummies

Hello! I’m Anna O’Neill, a summer intern working in the Conservation Department at the Penn Museum. I’m currently studying to get my MSc in Conservation Practice from Cardiff University in Wales. This summer, I’ve been helping Molly in the Artifact Lab a few days a week and she asked me to write a little bit about one of my projects.

The Egyptians often made votive animal mummies—small, mass-produced animal mummies that pilgrims could offer to the gods. Cats were especially popular as they represented Bastet, the cat-headed goddess of protection, fertility and motherhood. The Penn Museum has several cat mummies in their collection. A few are below:

cat mummiesWe recently started working on E16205, a cat mummy from Abydos (seen below in the image on the left). It was excavated in 1901-02 through the Egypt Exploration Fund through financial support of the Penn Museum, and dates to ca. 381-343 BCE. The linen wrappings are in bad shape—loose, torn and powdery—but that is the least of its problems. After a light cleaning, it became clear that something was missing.

overhead and vertebraAs you can see in the image on the upper right, the linen is damaged and there is a bone exposed at one end of the cat mummy. Zooarchaeologist and Penn professor Dr. Kate Moore confirmed that it’s a cervical vertebra visible at the narrower end of the wrappings.

Dr. Kate Moore examines the exposed cat mummy bone

Dr. Kate Moore examines the exposed cat mummy bone

Animal mummies occasionally lose their heads, as the neck is the weakest point of attachment to the body. Back in March, Molly wrote about our falcon mummy’s floppy head.

In the hope that maybe the head had simply been misplaced, we sent an email to Egyptian Section curator Jen Wegner. A few hours later, Jen turned up in the Artifact lab, smiling and toting a small, tissue-wrapped package. Inside was this little beauty:

Cat head 3quarterIt is evident that this head does not match our cat mummy’s body. The colors and weaves of the linen are different, and the head has carefully articulated features while the body is rather haphazardly wrapped. But the main difference is that there doesn’t appear to be any cat parts within the sculpted wrappings! Inside, the mask contains bundles of linen and resin, but no bones that we could see. A quick look at the records for the head showed that it was X-radiographed in the 1980s and contains “no bony skull”. It is a fake—but an ancient one!

Cat head above below

Additional views of the cat mummy head from above (left) and below (right)

Faking mummies, particularly animal mummies, was not uncommon in ancient Egypt. The materials to make a mummy, like myrrh and natron, were costly. Instead of embalming, the expense could go towards elaborate wrapping and detailing. Once the linen was in place, a religious pilgrim wouldn’t know whether or not there was an actual mummy inside. Several other Penn Museum animal mummies were X-radiographed along with the false head, and it turned out that the middle cat mummy in the image at the very top of this post doesn’t contain any skeletal matter, either. A clue is in the shape of its body—it is wide at the top and narrow at the feet, upside-down in comparison to the real cats.

So, were the mummy-makers pulling the, ahem, linen, over devotees’ eyes?  It is unclear whether the pilgrims knew that the votive mummies they offered to the gods were impostors, and nor do we know if it mattered. The qualities represented by the animal sacrificed may have been more important than its physical body. This way, a fake mummy representing the “idea” of a cat was an equally valid gift as the mummy of a real cat.

We’re disappointed that we can’t reunite our cat mummy body with its head, but Molly and I are going to work to stabilize the wrappings so that it can be CT-scanned and studied. In the meantime, it’s been interesting to see which of the Penn Museum’s votive mummies are real and which are (ancient) fakes.

 

Unwrapping mummies?

If there is one thing that I try to emphasize to visitors to the Artifact Lab, it is that we are NOT unwrapping or cutting open mummies. While this type of examination may have been appropriate and acceptable in the past (think PUM I) we don’t do this anymore. As you may gather from the title of this blog and our project, we are focusing on the conservation of our mummies, and we do this by aiming to use non-invasive and reversible examination and treatment techniques as much as possible. Our ability to carry out our work with much less interventive procedures than those used in the past is due in part to advances in technology. And when you see what is possible with new technology, you can see why autopsying mummies just doesn’t, errr…cut it.

Take, for example, one of our mummies that was CT-scanned back in 2009.

Hapi-Men on display in the Secrets and Science exhibit

Hapi-Men on display in the Secrets and Science exhibit (Hapi-Puppy is by his feet!)

As part of a larger CT-scanning project funded by the National Science Foundation, Hapi-Men, along with his puppy (Hapi-Puppy) was CT-scanned at the Department of Radiology at the Hospital of the University of Pennsylvania (HUP) (a special thanks to Felicia Williams and Erica Durham for this work!).

Although Hapi-Men had been x-rayed in the past, this type of examination is limited in that it does not provide much detail of any of the preserved soft tissue and other materials (like amulets) included in the mummy’s wrappings. But CT-scans can help reveal these details, and they also allow for 3D reconstructions, like the one you can see below, created by Penn graduate Samantha Cox under the supervision of Dr. Janet Monge.

CT-scanning, combined with other imaging techniques such as photogrammetry and laser scanning, leads to some pretty amazing virtual representations of mummies. Most recently, such work has been carried out in a collaborative effort between The Museum of Mediterranean and Near Eastern Antiquities in Stockholm, a group of Swedish visualization researchers, FARO (a 3D technology company) and Autodesk (a software company focusing on 3D design). This collaboration has resulted not only in the capture of new information for researchers, but the creation of an interactive exhibition for museum visitors, scheduled to open in Stockholm in February 2014. The interactive part of the exhibit, created using Inside Explorer will allow both museum staff and visitors to use simple gestures to virtually unwrap the mummies and to explore their multiple burial components.

You can read more about this exciting project, and see several images and videos of the process by following this link.

Our current work to conserve the mummies and funerary items In the Artifact Lab will stabilize some of these fragile objects enough to allow us to CT-scan them, and hopefully so that we can create some of our very own interactive exhibition features in the future.

 

The “conservation story” of Nefrina’s Funerary Mask, Part 1: Condition

Now that Nefrina is on display, I thought it might be helpful to discuss the condition of the mask as well as the treatment it underwent in 2011. Just as a bit of background, the mask has been in the Penn Museum’s collection since 1893 and was recently on display at the Reading Public Museum in Reading, PA.  Below you can see the mask before treatment.

nefrina image 1When the mask arrived to the conservation lab in 2011, it was a return visit. In 1993, the mask was stabilized for in-house photography, but this treatment did not address the many structural and surface issues that really needed to be taken care of before the mask could travel to Reading or be displayed.

As was mentioned in the previous posting about Nefrina’s funerary mask, it is made of cartonnage which is a composite material consisting of layers of linen and papyrus impregnated with glue that has been covered with plaster and painted. This type of material is prone to damage because of the differences in properties of the layers: the linen is flexible and the paint and gesso layers are rigid and brittle. As a result, when the mask is moved or stored unsupported the textile will bend causing damage to the gesso and paint layers.

The damage that the mask had sustained is highlighted in these condition maps, prepared during examination prior to the 2011 conservation treatment:

nefrina image 2nefrina image 3As you can see the cracking and loss to the paint is worse on the sides; this is likely because prior to 1993 the mask had no storage mount and probably rested flat on its back with the face pointing up. This position would have allowed the linen to flex and bend on the sides causing the paint to crack and detach from the surface. Areas on the front and back of the mask were also distorted and dented, also likely as a result of lack of proper support.

In addition to these surface issues, the mask also had tears and losses to the linen support. The tears and losses were temporarily stabilized in 1993 with the addition of internal patches made of spun bonded polyester lightly tacked in place with an adhesive. Again, these details are highlighted in the condition map below:

nefrina image 4The goals of the treatment in 2011 were to stabilize and realign the tears, compensate structural losses, and stabilize cracks, which will be discussed in an upcoming post.

- posted by Tessa De Alarcon

 

Elephant and giraffe hair? No problem!

There are many reasons why I love working at the Penn Museum, and this is one of them: just the other day, I was casually talking to some colleagues during a break, and mentioned that I’d love to get my hands on some elephant and giraffe hair to use as a reference to compare to some of the material included in our Predynastic mummy Bruce‘s bundle.

“What’s that you say?” quipped Egyptian Section Curator Dr. Jen Wegner. “Why it just so happens that we have a drawer with some elephant and giraffe hair down in storage!”. After working here for 9 months, this should come as no surprise to me. And what a delight – just the next day I ran down to storage and brought this drawer of goodies up to the lab.

Contents of the drawer, containing bits of elephant and giraffe hide, with the hair intact.

Contents of the drawer, containing bits of elephant and giraffe skins, with the hair intact

In addition to the animal skins, this drawer also contains a small woven basket, made of either elephant or giraffe hair and dating to the early 18th Dynasty, according to it’s catalog card.

Overall view of the small basket made of elephant or giraffe hair

Overall view of the small basket made of elephant or giraffe hair

These materials will be useful to compare to the animal skins and the basket that we have documented in Bruce’s bundle. We will provide updates as we learn more about our Predynastic mummy and the materials he was buried with.

 

From the Archives

The Penn Museum Archives is an incredible resource for us here at the museum.

A view into the Penn Museum Archives

A view into the Penn Museum Archives

When we begin working on objects in the conservation lab, we carry out preliminary research, which often includes searching for related materials in the Archives. Among the materials we may be interested in are archaeological field notes, letters between curators and archaeologists or collectors about the acquisition of specific artifacts, and old photographs.

Recently, Senior Archivist Alex Pezzati scanned some images for me, including this one, a shot of the Egyptian “Mummy Gallery” in 1935.

31011_mummyroom_1935_compressed

I was excited to see some of the artifacts we’re working on in the Artifact Lab right now in this photo. Can you pick some of them out? In the image below I’ve circled some of them in red.

The objects circled in red above are either being worked on in the Artifact lab or are on display in our accompanying exhibit

The objects circled in red above are either being worked on in the Artifact lab or are on display in our accompanying exhibit

These old exhibition photographs can be extremely valuable to conservators. Not only does this particular image tell us that certain artifacts were definitely on display, and when (which may not be recorded elsewhere), but it also shows us how they were displayed. In some cases, seeing the way that artifacts were previously displayed may help to explain damage, such as excessive fading on one side or adhesive residues left behind by an old mount. We can often make good guesses about this type of damage, but it’s always nice to have some proof!

What particularly excited me about this photograph is that it shows the coffin of Tawahibre in the gallery. We are currently working on this coffin in the lab, but it is still too fragile to separate the lid from the base to allow for examination of both pieces individually.

The coffin of Tawahibre in the Artifact Lab.

The coffin of Tawahibre in the Artifact Lab.

Just recently, Curator Dr. Jen Wegner was up in the lab and we were discussing the coffin and some of my observations, and she wondered out loud if the back had any text written on it. I had wondered the same thing myself but I knew that until we carried out further work, we wouldn’t be able to know.

BUT, since this 1935 photograph shows both the lid and the base of the coffin on display, we don’t have to wait any longer!

The lid and the base of Tawahibre's coffin, side by side in the Mummy Gallery in 1935.

The lid and the base of Tawahibre’s coffin, side by side in the Mummy Gallery in 1935.

As you can see in the above image, there is writing on the back! Now only if we could just hasten the conservation treatment so we can examine it for ourselves…

Another thing that is useful about this image is that is shows that much of the damage we’re seeing on the coffin today was present in 1935. This includes both major structural damage and extensive paint loss in areas. It is likely that the coffin came into our collection with this damage, which is somehow reassuring to me. I will also note this in my documentation.

Tawahibre's coffin in 1935 (left) and today (right). Much of the major damage we see today had already occurred by 1935. To highlight this, I've circled some of the damaged areas in red in both images.

Tawahibre’s coffin in 1935 (left) and today (right). Much of the major damage we see today had already occurred by 1935. To highlight this, I’ve circled some of the damaged areas in red in both images.

We continue to plug away on the treatment of the coffin and we are hoping to soon reach the point where we can separate the lid. I will provide an update shortly about some of the more recent work we have been carrying out on this artifact!