Tawahibre all tied up

Posted on April 13, 2013 by mollygleeson

When I wrote about the fantastic image we retrieved from our Archives a couple weeks ago showing our Mummy Gallery in 1935, I promised to provide an update on the treatment progress on Tawahibre’s coffin.

Well, why don’t I start with this:

A view of Tawahibre’s coffin from above

While you may not be sure what you’re looking at here, this looks like progress, doesn’t it? I’ll tell you what you are seeing – the coffin is tied in several places with cotton twill tape, holding small pieces of white Volara foam and blueboard (acid-free, lignin-free corrugated board) in place against the coffin surface.

A detail of the Volara foam and blueboard held in place with cotton twill tape

The purpose of this system, other than looking kind of intriguing, is to place select pressure in areas on the coffin (whenever I say this I always think of the useful book The Gentle Art of Applied Pressure-the title speaks for itself). As I have described previously, the coffin is pretty distorted in areas, due to the fact that many of the individual wood elements have separated and moved apart and that the plaster has separated from the wood substrate. We are trying to realign these pieces as much as possible using humidification with a Preservation Pencil, which allows us to direct a small stream of warm humidified air in select areas, which helps the plaster and wood relax a bit and encourages movement. Once we get an area to move sufficiently, we then apply pressure to the area to hold everything in place.

Here Nina is directing a stream of humidified air with the Preservation Pencil and I am applying pressure with my hands.

We’re also continuing to consolidate the painted surface and readhere loose pieces of plaster and wood.

We don't usually work in teams, but yesterday we had a little group humidification and consolidation party!

This treatment has been a team effort, and yesterday we had a little group humidification and consolidation party!

While we’re making progress and becoming pretty comfortable with the coffin and the treatment, there are still some scary areas to deal with. This is an area that I’ll be tackling next:

A detail of a badly damaged area on the coffin, showing significant cracking and flaking and detached and displaced fragments

Wish us luck as we continue this work!

From the Archives

Posted on April 3, 2013 by mollygleeson

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

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.

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

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.

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.

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.

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!

Mystery fiber

Posted on February 23, 2013 by mollygleeson

In a recent blog post I mentioned that I am working on the painted coffin of Tawahibre, which has fibers mixed into the ground layer (gesso). In my examination prior to starting treatment, I had noted these fibers, and observed that they are present all over the coffin lid, mixed into the ground layer just below the painted surface. They are exposed in many places where there are losses-here is an image of one area where the surface of the coffin is badly damaged, revealing these fibers:

Fibers visible in the ground layer of the painted coffin lid

There are quite a lot of these fibers in some areas (as seen in the photo above), and then in others, there are very few. They are found in areas where the ground is thick and also where it is applied very thinly. They are not arranged in any particular way-they appear to have been mixed haphazardly into the ground. The fibers are light brown in color, and while most of them are very stiff, they react almost immediately to moisture, becoming very flexible when wet. I had initially assumed that these were plant fibers-possibly flax-but they always seemed a bit odd, and to be honest, these fibers remind me a little bit of sinew (animal tendon).

As I have been working on the coffin, several of these fibers “presented themselves to me” for sampling-meaning, as I’ve been working to stabilize some of the areas with these fibers, a couple became detached, allowing me to investigate them further using PLM. So far I have looked at 2 samples, and both look the same. I prepared the fibers by mounting each one on a glass slide with water. When looking at them in plane-polarized light, they look like this:

Two different fibers from the coffin ground layer viewed at 50X magnification

I didn’t really know what I was seeing-it was difficult to pick out any really distinguishable features, so I then viewed both fibers under crossed polars. This is what I saw:

Same two fibers viewed under crossed polars at 50X magnification

What the heck is that? I’ve never seen anything like this before. When I showed this to a few other people, the first reaction has been-it looks like a worm! And it totally does. This very regular banding pattern has got to be characteristic of something-I just don’t know what.

I thought I had a lead last week-I found this image in a book, showing a bundle of sisal fibers with a commonly-seen spiral element:

Sisal sample showing a characteristic spiral element. Image from “Color Atlas and Manual of Microscopy for Criminalists, Chemists, and Conservators” by Nicholas Petraco and Thomas Kubic, p. 94.

However, just last week I obtained a sisal sample from one of the Winterthur art conservation graduate students and I’m pretty sure that’s not what I have. The sisal sample looks distinctly different to me-here it is in both plane polarized light and under crossed polars:

Sisal reference viewed at 400X magnification in plane polarized light (left) and crossed polars (right). Also, note the difference in magnification between these fibers, viewed at 400X, as opposed to the coffin mystery fibers above, viewed at 50X.

For the moment, I’m stumped. But I’m continuing to investigate this and to get input from colleagues, and I’m open to suggestions/ideas! I’ll also certainly provide more information when I know more. To be continued…

A sticky issue: choosing a consolidant for our painted coffin

Posted on February 9, 2013 by mollygleeson

In a previous post, I described some of the issues we’re facing in the treatment of our painted coffin of Tawahibre.

The top of the coffin before treatment – note the large losses and areas where the paint and gesso are just barely hanging on by a (plant fiber) thread

We’ve managed to clean much of the painted surface, but there are many areas of the paint and gesso that are so fragile, you get the feeling that a deep exhale – not to mention a sneeze – would send fragments flying. (And when I say gesso, I’m referring to the calcium carbonate preparatory layer/ground, which has plant fiber inclusions, that I’d like to investigate further).

Such areas require consolidation. We use this word, consolidation, a lot in conservation, and many of our treatments involve this process. Consolidation is essentially the reunification/reinforcement of a weak or powdery substance through the application of a material that we refer to as a consolidant. Consolidants often consist of dilute adhesive solutions, and they may be applied directly to artifacts with a brush or syringe, by spraying onto the surface, and in some instances, it may be appropriate to immerse an artifact in a consolidant solution. Ideally, a good consolidant must be stable (good aging properties), reversible (can be removed if necessary), and should not change the appearance of the artifact.

We have mixed up a variety of consolidant solutions to have on hand in the Artifact Lab – here are a few, along with some brushes, a plastic pipette, and syringes

Choosing an appropriate consolidant requires testing ahead of time. To start, it is important to test a variety of solvents (such as water, acetone, ethanol) – knowing which solvents can be used safely on a particular artifact will likely narrow down the range of adhesives that can be used (due to the fact that many adhesives are only soluble in a select number of solvents). In the case of our painted coffin, this involved testing all of the colors of the painted surface as well as the gesso substrate. Testing was carried out by rolling a swab dampened with each solvent over a discreet area and then observing the area for changes.

Solvent testing on an area of blue paint

After carrying out these tests, I did some research into what other conservators have used successfully for similar treatments on similar artifacts. In our field, we are fortunate to have a good body of published literature, and there is increasingly more information that can be found on the web as well. The sources I referred to included articles in the Journal of the American Institute for Conservation (JAIC), and a variety of books that have been published on the subject of conservation of Egyptian collections. Websites/blogs that I have found really useful include Inside the Conservator’s Art: A behind-the-scenes look at conserving Egyptian artifacts at the Phoebe A. Hearst Museum of Anthropology, conservator’s entries on the Brooklyn Museum blog, and the British Museum’s online collections database, which has many records with detailed conservation treatment information. There are actually lots of great blogs and websites out there, and I am grateful to my colleagues for actively sharing information in this way.

After this work, I selected several consolidants, and conducted another round of testing. During my testing I discovered that water was the key to getting the paint and the gesso to relax. Unfortunately, the painted surface is sensitive to water, but I found that a 50:50 mixture of water and ethanol is acceptable for use, especially when applied in a solution behind the lifting paint. In the end, we’ve chosen to consolidate the very fragile paint with a solution of methyl cellulose (a water-soluble cellulose ether) in a 50:50 water/ethanol mixture. To re-adhere larger flakes and chunks of gesso, we are experimenting using higher concentrations of methyl cellulose alone, and in combination with other adhesives, including Lascaux, a water-based acrylic resin.

An area near the foot of the coffin, before (left) and after (right) readhering detached gesso and consolidating paint

As I’ve stated before, this will be an ongoing project in the Artifact Lab – we will continue to report on our treatment progress, and any interesting discoveries made along the way (which is inevitable!).

Flaky, crumbly, and fragile: approaching the treatment of our painted coffin

Posted on January 24, 2013 by mollygleeson

Overall shot of our painted coffin, before treatment

Okay, you have heard a lot about PUM I lately, but there are other things going on in the Artifact Lab as well! Awhile ago, I wrote about the painted coffin of Tawahibre we have in the lab, that is in poor condition and is requiring significant conservation treatment.

This has been an ongoing project in the lab, as visitors may have noticed. I am not the only one working on this – treatment of this painted coffin has turned into a group project, and conservators Lynn Grant, Julia Lawson, and Nina Owczarek are also working on the coffin during their time in the lab, usually on Sundays.

Before I write a little bit about what we’ve been doing, I wanted to mention the fact that I’m referring to this object as a coffin, and not a sarcophagus. I have heard others – both museum staff and visitors – use both words when referring to it, and I have caught myself doing it too, and I thought this could be a little confusing. I am going to stick with the word coffin, because coffin typically refers to the container closest to the body, while a sarcophagus (which I read derives from the Greek for “flesh-eater”, apparently from a Hellenic belief that some stone used for body-containers actually consumed its contents!) refers to the outer case. Sarcophagi are also essentially rectangular, while coffins can be rectangular or anthropoid (meaning human-shaped) – our coffin is anthropoid.

Okay, now that we have that out of the way, I’ll start telling you what conservation treatment has been carried out on our coffin so far. I wrote in my previous post that after full documentation, we removed accumulated dust from the surface with a HEPA-filtered vacuum and a soft brush. Then, after some test-cleaning, we continued to clean the coffin using cosmetic sponges. While I was originally finding success cleaning the surface with Groomstick, it ended up being too sticky for fragile areas, and the cosmetics sponges work just as well, and especially in very small, delicate areas.

A section of the coffin before (left) and after (right) cleaning with a vacuum/brushes and cosmetic sponges

This initial cleaning has made a huge difference. There are a lot of areas on the coffin, however, that cannot be cleaned until they are stabilized. There are many areas where the paint, along with some of the gesso ground, is cupped and lifting, or completely displaced.The exposed gesso ground in these areas is very fragile and crumbly.

An area on the coffin where the paint is cupped and lifting away from the surface, revealing the gesso ground below.

In other areas, the paint and ground have completely separated from the wood substrate.

A large piece of paint and gesso that has separated from the wood below.

After a lot of testing, we have started stabilizing, or consolidating, the flaking and displaced paint and gesso with a very dilute adhesive solution. We are also re-adhering loose and detached pieces of gesso and wood. In my next post, I will describe the testing involved in choosing adhesives, the treatment methodology that we’ve developed, and some of the complexities we’re facing in treating this fragile object.

pXRF follow-up

Posted on November 9, 2012 by mollygleeson

A couple weeks ago we brought out our portable X-ray fluorescence (pXRF) analyzer to aid in our study of some of the objects in the Artifact Lab. We provided an overview of this session earlier on our blog-read more by clicking here.

One of the objects that we looked at with the pXRF is this painted wooden coffin. I also wrote a blogpost about this artifact and you can read more about it there.

Painted wooden coffin of Tawahibre

A critical part of the conservation process is examining and documenting objects-their materials, technology, and condition-all of this information is recorded in condition/treatment reports. Beyond saying that this coffin was decorated with red, yellow, white, black, and blue paint, we would like to provide more information in our report about which pigments were used, if possible. Based on knowledge of the painting materials used in ancient Egypt, we had some ideas, and we were hoping that the pXRF could confirm that our ideas were on the right track.

One pigment we were interested in knowing about is the blue. Here is a detail of the blue paint in one area:

Detail of coffin, showing blue paint

Considering that Egyptian blue was the principal blue pigment used in ancient Egypt, this was our first guess. Egyptian blue is a synthetic pigment, one of the first synthetic pigments ever produced, made by heating together copper, silica (sand), lime (calcium oxide) and an alkali such as natron (sodium sesquicarbonate). This pigment is found on objects from as early as the 4th Dynasty through to the Roman Period. The hue varies from dark to light blue, depending on the components and the grinding process (or the final particle size). Dark blue colors tends to have a larger particle size and smaller particles produce a lighter blue.

So how can the pXRF help us understand what blue pigment was used on this coffin? Well, as previously described, XRF is useful for identifying elements present in a sample or targeted area of an object. We simply positioned the pXRF in contact with the area of interest, in this case, a stable area of the blue paint, and took a reading.

The pXRF analyzer positioned in contact with the target area of interest

The reading produced a spectrum with peaks representing the x-ray energies of the elements present.

pXRF spectrum of the blue paint from the coffin

Here we have labeled the peaks of each element detected-you can see that there are very high peaks for Calcium and Copper. This is what we would expect to see for an Egyptian blue pigment!

We’re looking forward to continuing to use this technique for examining other objects in the Artifact Lab-especially those artifacts with only traces of paint left or those objects with surfaces that have darkened and where the original colors are more difficult to interpret. We’ll continue to update the blog with this information as we find out more.

Painted wooden coffin of Tawahibre

Posted on October 25, 2012 by artifactlab

By now, many of you may be familiar with this object from it’s appearance in our recent media coverage:

Painted wooden coffin from the Late Period

This is a painted wood coffin from the Late Period, post-558 BC. It has been fairly inaccessible in storage until coming up to the Artifact Lab. Now that it’s up here, we’re realizing that it’s going to be a complex project, in more ways than one.

First of all, it’s a bit confusing who this coffin belonged to. In our records, is listed as the coffin of Tawahibre or Teker-Wah-Eb-Re. The mummy associated with the coffin was x-rayed in 1932 and examined in the 1970s and both times determined to be a woman in mid-adult life (about 40 years old). However, in 1946, the hieroglyphic text on the coffin was translated as identifying a male court official, the son of J-se(t)-N-Ese. Our curators are going to work to translate the text to see if we can figure out who the coffin belonged to…however…

The second complication is that, unfortunately, this coffin hasn’t aged particularly gracefully, and it is now very fragile and in poor condition. And even more unfortunately, the areas that contain much of the text are in the worst condition, with major losses to the painted surface.

Detail showing major paint loss across the foot area of the coffin

So, one of the first things we’ve done to improve the condition of the coffin and aid in translation is to remove years of accumulated surface dust using a soft-bristled brush and a HEPA-filtered vacuum. This made a big difference and already allows the text to be read more easily. I am now conducting cleaning tests to see how much more surface grime can be removed. I did some dry-cleaning (meaning cleaning without the use of solvents like water or alcohol) testing today using Groomstick, a natural rubber product similar in consistency to SillyPutty, and cosmetic sponges, and I’m pretty happy with the results. Look at how much more dirt I was able to remove with these products:

Partially cleaned surface (left) and bits of Groomstick and cosmetic sponges after dirt removal (right)

Next I’ll have to start addressing how to approach the stabilization of the fragile and flaking paint and gesso and unstable wood elements.

Posted by Molly

In the Artifact Lab-Week 1

Posted on October 5, 2012 by artifactlab

And what a week it has been! We are officially moved in to our new conservation lab, up on the 3rd floor of the museum and work is now underway in the Artifact Lab.

A view of the Artifact Lab from the entrance to the gallery

Since we opened on Sunday, we’ve spent the week getting situated in our new lab, preparing our work space, tools, and materials, and starting to examine several of the objects we’ll be working on over the next few months. We have a fascinating variety of objects in the lab-including mummified human remains, mummified animals, and funerary items such as painted and inscribed coffins and coffin boards (parts of coffins). These objects have spent many years in storage, some of them since being acquired by the museum over 100 years ago. One of the huge advantages of working on them in the new Artifact Lab is that we have the space, suitable lighting, and proper equipment to thoroughly examine and research these objects, and in the last few days, it quickly became clear that in several cases, we have our work cut out for us.

This painted wood coffin, for instance, is going to be a major project-

Wood coffin dating to the Late Period (post 558 BCE). Notice the heavy layer of grime and significant cracks in the paint and gesso layers.

It’s surface is heavily obscured by dust and grime, and it also has significant structural issues as well, including severe cracks that extend though the paint, gesso and wood and significant losses to the painted surface. We can already tell that this will be a project that will be ongoing in the lab for awhile.

Oh, and in addition to our regular conservation lab work, did I mention that we’ve spent a lot of time this week speaking with the public? Our work will always be visible to anyone who stops by-our Head Conservator Lynn Grant appropriately refers to the space as a fishbowl-there is literally, nowhere to hide (and if there was I wouldn’t tell you). But twice a day, 11:15am and 2:00pm Tuesday-Friday and 1:00pm and 3:30pm Saturday and Sunday, we open the windows to answer questions and speak about our work. We also have the advantage of using our new Smartboard to show additional images-photos showing the progress of our work and images collected through research.

We use this Smartboard for presentations and also for communicating to visitors when we are working.

Stay tuned for upcoming posts featuring some of the objects that we’ll be working on in the Artifact Lab, and some of our latest discoveries!