Spring cleaning?

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

coffin board cleaningHe also posted this on our Instagram page.

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

E12617A-C, boards from a painted wooden coffin

E12617A-C, boards from a painted wooden coffin

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

To see the process of how we go from

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

corner before after

click on the link below.

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

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

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

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

Multispectral imaging of Wilfred/a’s cartonnage

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

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

E12328B_visible01_compressed

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

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

E12328B_IR01_compressed

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

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

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

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

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

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

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

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

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

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

Conservation at the Penn Museum: the next generation

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

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

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

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

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

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

Jar of dirty cotton swab tips

Jar of dirty cotton swab tips

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

 

Jessie with a successfully-rolled swab

Jessie with a successfully-rolled swab

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

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

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

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

 

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

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

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

TessaJessieKate

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

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

Heron bones

Heron bones with sharpie marker used for scale.

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