2013 Philadelphia Science Festival Preview

Posted on March 12, 2013 by mollygleeson

Our table at the Science Festival Press Preview night, featuring our portable XRF analyzer and a Proscope. At right, Lynn demos the Proscope, magnifying a piece of linen at 50X.

Last night, Lynn Grant, Penn Museum Public Relations Director Pam Kosty, and I went to the Franklin Institute for a Press Preview for the 2013 Philadelphia Science Festival. Our museum is hosting a signature event for the Science Festival this year, entitled: “Long Live Our Treasures: The Science of Conservation and Preservation.” We have partnered with 17 other organizations for this program, which will spotlight the typically “behind the scenes” work of conservation professionals through demonstrations, exhibits and short talks. All of this will be taking place on Wednesday April 24 from 5-8pm at the museum.

At the preview last night, we got a taste (literally) of some of the other programming that will be taking place at the Science Festival, including a chance to try fruit from a cacao pod, thanks to Mars Chocolate Research Fellow Ed Seguine (who tastes chocolate for a living – how envious am I?) and a sample of chocolate bourbon habanero ice cream made with liquid nitrogen (so delicious and creamy!) made by the evening’s host, the Franklin Institute.

A partially opened cacao pod (left) and the liquid nitrogen-prepared ice cream being served (right)

At our event for the Science Festival on April 24, we are looking forward to sharing our work in the Artifact Lab – we will be open till 8pm that evening and visitors will have a chance to use our Proscopes (like the one in the image above) and learn about how we are conserving mummies and other Egyptian materials. This event also, appropriately, coincides with National Preservation Week. We’re excited to be hosting this program and highlighting the field of conservation, and we hope that those of you in the Philly area can join us for this!

A technical study of a child sarcophagus

Posted on March 6, 2013 by mollygleeson

Casey analyzing the surface of the child sarcophagus using a portable XRF analyzer. Photo by Vanessa Muros

I have a special treat for our readers today – I recently had an interesting discussion with Casey Mallinckrodt, a current graduate student in the UCLA/Getty Program in the Conservation of Archaeological and Ethnographic Materials (which is also my alma mater!).

As part of her graduate studies, Casey has been working on a rare example of an Egyptian child sarcophagus, and instead of recounting the conversation for everyone, I asked her if she’d be willing to answer a few questions for our blog. Read on to hear more about Casey and this fascinating project.

1. First, tell our readers a little more about yourself.

I am a second year MA student in the UCLA/Getty Program in the Conservation of Archaeological and Ethnographic Materials. This is a career shift for me having received an MFA in sculpture in 1988 and having had a career in fine arts and education. I did pre-program internships in conservation at the Museum of Modern Art and the American Museum of Natural History in New York before applying to this program.

I am working on this project with Dr. David A. Scott and Prof. Ellen Pearlstein, both of whom are faculty in our program. Marie Svoboda, a conservator of antiquities at the Getty Villa, and Dr. Kara Cooney, an Egyptologist at UCLA are advisors.

A view of the upper half of the sarcophagus

2. Tell us more about this child sarcophagus that you’re working on and why it is so unusual (that’s assuming that it is!!)

The sarcophagus (or coffin) lid is on loan for this project from the San Diego Museum of Man. It was given to the museum in 2001 and it dates to the Ptolemaic period, 305 – 30 BCE although the exact date of this object is not known. It is unusual because sarcophagi were costly and rarely made for children. This is supposed to be one of only seven from this period known to exist. It seems to have been for a girl, and scholars I consulted suggest she may have been a child wife, which would justify the expense. Many people have asked about the mummy and the base of the coffin but these are unknowns.

It is made of a carved out section of a tree trunk with pieces added to create the chest, face and foot. Wood dowels were used to secure the pieces in place. The exterior is completely covered with a polychrome layer made up of a base of a brown granular paste, then a white “gesso” layer and the paint applied onto that. The interior is unpainted.

A side view of the sarcophagus in the UCLA/Getty labs

3. What is your ultimate goal for this project?

The project is a technical analysis of the structure and materials, and development of a treatment plan. The treatment goal is to stabilize the structure and fragile paint layer, and reduce or removal modern fills that may be damaging the original materials. If the museum approves I will carry out treatment in selective areas to establish a protocol so the museum can continue the work after the coffin returns to San Diego in June.

4. Since I get asked this question almost every day, I’m going to turn around and ask you – what is the most interesting and/or unexpected thing that you’ve found so far in your work on the sarcophagus?

It is a fascinating project in so many ways, but two things come to mind. One involves the manufacture, and the other a mysterious surface condition.

The ancient Egyptians frequently reused parts of coffins and I have found evidence of reuse here. X-rays reveal empty dowel holes that indicate changes in the structure, and there are modern metal screws holding the foot block in place.

X-radiographs of the head (left) and foot (right) of the sarcophagus. Note the modern screws holding the foot together.

Scholars I have consulted find the carving of the face more consistent with earlier periods. I am examining the types of wood and indications of changes in the construction, and analyzing the pigments, gesso, fill materials, and coatings to identify differences that might point to different sources for the different parts.

The most unexpected development was the emergence of small waxy exudates on the lower front of the “torso”. I am doing chemical tests on samples, and FTIR (Fourier transform infrared spectroscopy) is being carried out by Getty Conservation Institute Scientist Herant Khanjian to identify the substance and determine whether it poses a threat to the original materials. This is probably the result of a coating or consolidant that was put on the object, but there is no record of its treatment before SDMM acquired it.

Thanks Casey! This is a terrific project, and a great example of how conservation is often a very collaborative process, involving conservators, scientists, archaeologists, and other specialists.

I will be keeping up with Casey as her work progresses. For more information on the UCLA/Getty Conservation Program and other student projects, follow the links I’ve included in the text above.

Outside of the box: freeing a wall painting fragment from its frame

Posted on March 1, 2013 by mollygleeson

Exciting day in the Artifact Lab! We finally freed this wall painting fragment from its old frame-a frame that it has been in since before coming into our collection in 1925.

Wall painting fragment from Deir el-Medina, before treatment

You can read a bit more about this object in a previous post by following this link.

For the last several weeks I have been preparing for this task – I have spent a lot of time examining the painting, documenting its condition, and analyzing the materials used in its construction. I have carried out some cleaning tests and consolidated much of the painted surface. I also dug out a lot of the cracked and loose plaster surrounding the painting, so that I could fully understand how the painting was set into the frame.

A detail of the bottom of the wall painting with most of the surrounding (modern) plaster removed

All of this was necessary in order to carry out the somewhat daunting task of removing the painting from a frame that has done a great job of protecting it for close to 100 years. It had decidedly reached its useful lifespan though, which is why it needed to be removed. Removing the frame was also going to be the only way for me to evaluate the stability of the wall painting and its more recently applied (modern) plaster backing, and also offered the opportunity to do a more thorough examination of the mud plaster substrate.

When I decided that I was ready to try to remove the frame, I still wanted some moral support (and an extra set of hands and eyes), so I asked my co-worker, Penn Museum conservator Nina Owczarek, to come up and help me. And boy, was Nina more than ready for this-apparently she couldn’t wait to do a little destruction.

“This is why I am a conservator” Nina said as she pried off one of the frame elements with a twinkle in her eye.

After weeks of careful preparation-any guesses as to how long it took us to get the frame apart? Armed with just a screwdriver and a metal spatula, we managed to get it off with relative ease in less than 15 minutes. That frame was ready to come apart, and we didn’t need to use a saw to do it (thank goodness) which is what I had been expecting.

Here is the final result:

The wall painting lying next to its frame-bits of the paper and modern plaster from the side of the frame have fallen off to one side

And here are a couple views from the side, showing the thickness of the original mud plaster, and the plaster backing underneath, set onto a piece of plywood.

Two views of the wall painting, with bits of plaster and paper still partially adhered to one side

In the end, even though it got my heart pumping a little bit, it wasn’t really that nerve-racking after all – all of that preparation paid off! And Nina and I deemed it totally high-five worthy. I’m looking forward to working on this tomorrow, and to moving forward with this treatment.

Mystery fiber update

Posted on February 23, 2013 by mollygleeson

A quick update on our mystery fiber (see my previous post for details):

Today I decided to do a chemical spot-test to see if I could determine if the fiber was cellulose or protein-based. Chemical spot tests are inexpensive, generally simple procedures that conservators may use to characterize materials on artifacts. These spot tests are often carried out on small samples removed from artifacts using chemical reagents. In the case of my mystery fiber, I cut a small piece off of one of the fiber samples I previously examined under the microscope-this small piece was enough for a spot test, and there was no need to remove more material from the coffin in order to do this.

The first test I chose to carry out was the Biuret test for protein (according to instructions in Material Characterization Tests for Objects of Art and Archaeology), using copper(II) sulfate. After placing a drop of copper (II) sulfate solution on the sample, I waited for a few minutes, then soaked up the excess solution and added a drop of sodium hydroxide solution to the sample. It immediately turned purple (see below), which indicates the presence of protein (and just in case it’s not clear on your screen, believe me, it is purple!).

Magnified image of the sample used for the protein spot test. The purple hue indicates a positive reaction for presence of protein. 50X magnification

What this means is still unclear, but it’s another clue. It is possible that my earlier comparison of this fiber to sinew was not a bad suggestion! But it’s also possible that this fiber was coated in a protein-based glue before it was incorporated into the gesso (or something like this).

This calls for further investigation!

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…

Art conservation students visit the Artifact Lab

Posted on February 21, 2013 by mollygleeson

Last Saturday, I was pleased to give a special tour of the Artifact Lab to a group of students from the University of Delaware.

Group photo in the Artifact Lab

This group was made up of graduate students in the Winterthur/University of Delaware Graduate Program in Conservation (WUDPAC), a pre-program intern currently working in at Winterthur, and undergraduates majoring in art conservation at the University of Delaware.

Several students gathered for our open window session

They arrived during our open window session, and then we continued the tour afterward, which gave me the opportunity to present some of my ongoing work and experiences working in an open lab. While I speak about my work every day, discussing my work with students who are learning some of the latest treatment techniques and analytical methods, and who have this information fresh in their minds, was incredibly useful for me. Since their visit, I have received some generous offers of sharing material samples and articles. I know that visiting the Artifact Lab must have been a treat for them, but I think it was equally rewarding for me!

A step a- “head”: improving storage for our mummified heads

Posted on February 16, 2013 by mollygleeson

As I mentioned previously, we have several mummified heads in the Artifact Lab. Luckily, all of them are stable and do not require much in the way of conservation treatment – instead we have focused on examination, documentation, and some light surface cleaning, and in one case, the removal of an old exhibit armature.

We have a lot of things going on at the moment, so thankfully, I’ve gotten some help with this work. A couple weeks ago we had a group of 5 undergraduate art conservation students from the University of Delaware in the lab – they spent the month of January interning in our department on a project focused on documenting and cleaning a group of Arctic boats in storage.

Ellen Nigro and Rebecca Selig condition reporting a kayak

They wrapped up that project a day early, and so on the last day of their internship, they got to work on something totally different – and several of them elected to help condition report one of the heads.

Rebecca Cruz, Emily Cummins, and David Brickhouse examining a mummified head

After fully documenting the heads and carrying out any necessary treatment, our main goal is to construct new storage mounts for these remains. Our Egyptian storage areas are fairly packed with artifacts, and because of this, many things are stored in a way that makes them hard to access or see without a lot of handling.

An example of artifacts wrapped nicely in acid-free tissue in a drawer – unfortunately, there is a lot of handling required to see these objects

New storage supports will improve access and provide better protection for these remains. Our plan is to make handling trays for the heads, which can then be housed within custom-made boxes.

An example of a handling tray, made using acid-free corrugated board and Volara polyethylene foam

I’m getting some help with this as well – Artifact Lab intern Melissa Miller has been working on the first tray and box.

Melissa working on creating a custom-made box for one of the heads

We will be sure to post photos once we’ve completed them!

Giving our falcon a little love

Posted on February 12, 2013 by mollygleeson

One of my favorite artifacts in the lab is a falcon mummy, which I described in an earlier post. While he is a fascinating object, this poor little guy hasn’t been able to be exhibited, or even handled very much, because some of his linen wrappings are quite deteriorated, brittle, and breaking apart, causing serious structural issues.

Overall shot of our falcon mummy

Recently, I worked to stabilize the linen wrappings on his feet, which were partially detached, and in some areas, barely hanging on by a few threads.

Side view of the falcon’s “feet” showing the fragile, partially detached linen wrappings

Before carrying out any treatment, I did a little bit of research and carried out some testing to determine what materials I might want to use to repair the textile. I knew that a stitched repair would not be possible, as the linen fibers are far too weak and this would likely cause further damage, so I started investigating different adhesives and support materials to use instead. As part of this process, I consulted with Nancy Love, a local conservator in private practice who specializes in textiles. Nancy recently visited me in the Artifact Lab, and among the other materials I was trying, she suggested that I experiment with nylon bobbinett, a heatset nylon net.

I did some experimentation with it, and I really liked how it behaves, both as a support fabric and as an overlay to protect fragile areas-it drapes well and can be toned easily with dyes or paint. After feeling satisfied with the results of some of my tests, I set out to repair the damaged linen over the falcon’s feet.

I started by toning the bobbinett with Golden acrylic paint. Then I backed the fabric that was dangling off the back of the foot with the toned bobbinett lightly coated with 10% methylcellulose in water. I then used the bobbinett support fabric to raise the partially detached fabric up into place, secured temporarily with pins.

After positioning the linen, I covered the entire back of the foot area with another piece of toned nylon bobbinett.

The back of the foot area with an overlay of the toned nylon bobbinett, after treatment

Finally, I tacked down the strip of linen over the top of the feet, which was also partially detached but otherwise fairly stable, using small beads of methylcellulose. Reattaching the linen over this area also hid the edge of the nylon bobbinett overlay.

View of the front of the foot wrappings, after treatment

I’m pleased with the results, and I can now breathe a sigh of relief that we’re not going to lose any more of the linen from this area. My next task will be to address the falcon’s partially detached head/neck area. Hang in there, little guy!

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!).

Screaming mummies

Posted on February 6, 2013 by mollygleeson

Melissa Miller, our talented undergraduate intern from the University of Delaware, recently created a series of prints in her Intro to Printmaking class – inspired by…you guessed it…mummies!

For one of her projects, she was instructed to make a zinc plate etching of something emotionally significant to her. We have really made Melissa get down and dirty with our mummy PUM I – one of her projects in the Artifact Lab has been to sort through the bag that was found inside PUM I’s chest, which, as it turns out, was filled with fragments of textile from his wrappings, along with bones, fragments of skin and other soft tissue, and even a few more beads that originally made up his beaded shroud.

Just some of the materials that came out of that bag we found in PUM I’s chest

So it shouldn’t be surprising that Melissa may feel a bit…affected…by this subject. Here is one of her first prints:

Melissa’s first “Screaming Mummy” drypoint etching

Melissa chose to create an image of this particular “screaming mummy”, also known as Unknown Man E, for her project because of his dramatic expression, which inspired her to look into the context in which he was buried. Unknown Man E was discovered in the Valley of the Kings, which implies his high status. He was buried with a sheepskin, which was considered by the ancient Egyptians to be ritually unclean, and his organs were not removed, indicating that his body did not receive the traditional mummification treatment. It has been suggested that this man may have been Prince Pentewere, son of Ramses III. According to historians, Pentewere was involved in an assassination scheme against his father, the pharaoh, which was very recently declared to have been successful. After Pentewere’s trial he was permitted to kill himself. Such circumstances may explain Unknown Man E’s curious burial, and as some would suggest, the expression of horror on his mummified face.

While this seems to be a believable theory, as Mark Rose explains in his article “Screaming Mummies”, this open-mouthed expression is also found on other mummies, and may not be reflective of the circumstances of death or the expression on a person’s face at the time of death. For more on this subject, a link to this article can be found in the Learn More section of this site.

Whatever the truth may be, the image of Unknown Man E drew Melissa’s attention and, as she said, made him the perfect subject for her printmaking project.

After her first etching, she applied an aquatint, which allowed her to achieve a wider variety of grey tones. It also gave the image a grainy texture – which Melissa felt added a desirable ghastly feeling to the image.

Screaming mummy etching with aquatint

Finally, she achieved higher contrast between the darks and lights by re-etching some of the lines and enhancing the aquatint, producing this image:

The final, ghastly, image

All three of these images can be found side-by-side in the Fun Stuff section of our blog. I’d like to extend a special thanks to Melissa for her help with this post, and her creativity!