BIG changes, little details

On November 1, our Museum announced the commencement of our  Building Transformation  campaign, a monumental project which will include a full renovation of our building structure and reinstallation of many of our signature galleries, including our iconic Egyptian Galleries.

The first glimpse of this work will be the opening of our Middle East Galleries in April 2018. This is not news for readers of this blog – you have been hearing about the conservation work for this project for awhile now (for reference, see these related blogposts).

Graduate intern Marci Jefcoat Burton (standing) and pre-program interns Fallon Murphy, Jennifer Mikes, and Alyssa Rina during an open window session in the Artifact Lab (with one of the al-Ubaid mosaic columns in the foreground)

In fact, you can get a glimpse of several exciting projects that are underway for our Building Transformation right now, on a daily basis, in either of our 2 public conservation labs.

In the Artifact Lab, you will mostly see objects being conserved for the Middle East Galleries and for our Mexico and Central America Gallery, opening in November 2018.

An assortment of artifacts for the Mexico and Central America Gallery in various stages of conservation treatment.

Our other public lab is down in our Lower Egyptian Gallery. Work in that space is dedicated exclusively to conservation treatment of the carved and painted limestone blocks from the Old Kingdom tomb chapel of Kaipure.

A view of the Kaipure tomb chapel lab space in Lower Egypt

Project Assistant Anna O’Neill at work on a block in the Kaipure lab

While you can watch the conservation team at work most days in the Kaipure lab, unlike the Artifact Lab, it does not include open window sessions. But have no fear – the Kaipure team has promised to write some blogposts about aspects of their work, so stay tuned for more information on this project!

Big projects like the Building Transformation campaign come down to a lot of little details, and no one knows details like the Conservation Department. We hope you visit us to learn more about these details, and all the work underway to make these big changes possible.

Sometimes you just can’t get close enough (intern Celine Wachsmuth in the Kaipure lab)

To learn more about the vision of our Building Transformation, check out this ~3 minute video which captures the grandeur of the project (and features Project Conservator Tessa de Alarcon!).

A Columnar Matter Part I: The Technical Examination of a 3rd Century BCE Mosaic Column from Al Ubaid

Marci Jefcoat Burton

My first project as a curriculum intern with the Penn Museum Conservation Department involves the conservation of a mosaic column from the Ninhursanga temple site of the ancient Mesopotamian city of Tell al-Ubaid in Iraq (column in digital collections: (B15887.1 – 15887.4). Dated as 2400 – 2250 century BCE, the column was excavated sometime between 1919 – 1924 as a pattern of alternating triangular and diamond shaped shell, pink limestone and shale tiles. Fortunately, the years of resting in the compacted dirt of the burial environment preserved the shell and stone tesserae and maintained their original conformation. The original column interior, more than likely palm logs, did not survive the centuries of burial.

Figure 1 (left): Before treatment image of the four column sections stacked together to make a mosaic column.
Figure 2 (right): Reconstructed façade of the Ninhursanga temple of Tell al Ubaid. The columns were originally believed to be outside the entrance of the temple doorway, although it is not certain if both columns were on the exterior or interior of the building. (Both images courtesy of The Metropolitan Museum of Art. (2003). Art of the First Cities: The Third Millennium B.C. from the Mediterranean to the Indus. The Metropolitan Museum of Art: New York)

Without a support, the delicate tesserae were lacking a method of storage and display. Working with the materials available on site and with technology available in the early 20th century, the archaeological team constructed four drums to mount the tesserae into four stackable sections. Although reports attribute the original 3rd century BCE binding medium as bitumen (i.e., asphaltum, tar, pitch) to hold the tesserae in place on the original wooden supports, the 20th century excavation team reconstructed the shell and stone mosaic pieces with a grey plaster. In addition, only half of each drum holds original tesserae, and the remainder of each section is filled with a painted plaster reconstruction.

Figure 3: c. 1920s, on-site with the recently assembled tesserae onto the wire mesh and wood drums. (Image courtesy of http://www.mesopotamia.co.uk/tombs/story/page07b2.html).

X-radiography of one of the drum sections revealed that each drum is constructed as a hollow metal mesh cylinder with wooden caps on each end, and several nails to keep the cylinder together. After 100 years in this conformation, the drums have become problematic for the long-term display of the tesserae. Fluxuations in temperature and humidity, as well as the weight of the tiles and the thick, rigid plaster have caused opposing shifts in the internal structure, leading to the formation of cracks in the plaster and several tiles to dislocate and fall from the support.


Figure 4: X-radiographs of column section B15887.3 detailing the inner drum structure consisting of an open wire mesh and hollow interior. (Left (a)): X-radiograph of the column section side reveals the radiopaque grid pattern indicative of a metal mesh. (Right (b)): X-radiograph of the column section top, revealing numerous nails in various locations that hold the cylindrical drum together. (X-radiographs courtesy of Julia Commander (2016)).

The column, with all four sections, is one of the many objects selected for exhibition in the upcoming Middle Eastern Gallery (scheduled to open in Spring 2018). Therefore, it was decided it was time for the over 4,000 year old tesserae to be removed from the hollow wire mesh supports and then remounted onto a structured, solid support made with materials that will prevent structural damage and be sustainable for its preservation and long-term display in the gallery. Following a treatment protocol implemented successfully on one of the four column sections by Julia Commander (WUDPAC, Class of 2017), I will deconstruct the tesserae from the current supports, clean and repair each piece, and remount the tesserae in their same arrangement to new cylindrical supports made from solid, very dense Ethafoam measured to the exact shape for each section awaiting treatment. Stop by the Artifact Lab to see the progress of the column treatment, which is already underway, or stay tuned for a follow up blog post!

Figure 5: Start of the disassembly of the shell, pink limestone and shale mosaic tesserae from column section 2. Note the color difference of the large painted plaster fill on the left versus the original tesserae on the right. Several breaks are also observed in the inlays (most notably the beige shell pieces) and a layer of dark, brown grime has accumulated on the surface overall.

Cleaning – it’s complicated

by Lynn Grant

Not that long ago, a museum colleague was heard to say “I suppose cleaning counts as conservation” in a doubtful voice. We conservators found this both appalling and amusing as cleaning is a huge part of what we do. And knowing when and how to clean is a big part of our education. Using the wrong methods can permanently damage an artifact. Those of us who finished our conservation training more than ten years ago mostly relied on the rule of thumb ‘try gentlest methods first’. But there have been rumblings in the field about better ways to do things, with terms like Modular Cleaning Systems and Gel Cleaning drifting by. Clearly this was something we needed to know more about.

Richard Wolbers (in blue polo shirt) demonstrates basics of cleaning gel production to Museum conservators and interns

Fortunately for us, one of the ‘rock stars’ of gel cleaning research, teaches nearby at the Winterthur/University of Delaware Program in Art Conservation. Richard Wolbers, who describes himself as a ‘Cultural Materials Engineer’ to reflect his interest in applying new ways of thinking about conservation issues, is Associate Professor at WUDPAC and has graciously lent us his expertise on specific projects previously (one example here). But now that we have so many conservators and interns working on different projects and with a major campaign to reinstall our Egyptian Galleries after 90 years about to start, we asked Richard to give us a two-day workshop on the basics of gel cleaning. This was an abbreviated version of week-long workshops he gives around the world but we certainly squeezed a lot of learning into two jam-packed days.

The conservators and interns get into gel (and emulsion) production!

Richard has basically turned much traditional conservation ‘wisdom’ on its head: looking deeply into the complex interactions among surfaces, dirt, and cleaning materials and using his observations to develop new approaches to cleaning. Even gels aren’t the new frontier anymore; custom made emulsions may allow conservators to use water and solvents in combination when the surface is easily damaged by them when used in liquid applications. Many of the techniques and materials that Richard uses come from the cosmetics and food industries. In fact, as we listened to his explanations, I kept thinking of the Molecular Gastronomy movement. Some of our new cleaning tools have as much relation to our old way of doing things as this does to your grandma’s chicken soup:

Chicken soup spheres (http://jordancaterers.blogspot.com/2013/07/chicken-soup-spheres.html)

It’s a brave new world for conservation cleaning….

Conservation (training) in action

Our new curriculum intern, Marci Jefcoat Burton, was here for only couple weeks before we seemingly threw her to the wolves. That is, we asked her to work in the Artifact Lab and handle the open window sessions.

Marci describes her work to 2 visitors during an open window session

But we knew that Marci would do a stellar job working in front of the public and answering their questions. Although Marci is technically an intern, she already has extensive experience in conservation. In fact, as a curriculum intern, this is her final year of her graduate studies in conservation (she will complete her MA at the UCLA/Getty Master’s Program in the Conservation of Archaeological and Ethnographic Materials in June 2018).

One does not get to this point in their conservation training without a lot of experience working in conservation labs – to even be considered for an interview at many of the graduate programs, prospective students must have completed hundreds of hours interning with a conservator. More information about the path to becoming a conservator can be found here on the AIC website.

Marci is working on a number of projects here at the Museum, at least one of which she is basing in the Artifact Lab.

Marci working on a mosaic column drum from Al’Ubaid, Iraq (left) and examining an Islamic bowl at the microscope (right).

Stay tuned to the blog for more information about the column drum (in image above), and visit the Artifact Lab during open window hours for a chance to speak with Marci about her work!

Laser cleaning a trio of birds

In addition to the frieze of 6 bulls (which we are still working on in the Artifact Lab), we are also treating a frieze of 3 birds, in preparation for our new Middle Eastern Galleries, scheduled to open in April 2018.

B15883, frieze of 3 birds before treatment

This is a section of a frieze from the site of Al-Ubaid, Iraq which was excavated by Sir Leonard Woolley in the early 1920s. The birds are the only original pieces of the frieze – the rest is a modern reproduction. The birds (possibly doves?) were carved from limestone and each has a pair of drill holes at their center which would have served as an attachment point. Copper alloy twists would have been used to secure the birds in antiquity – fragments of the original copper remain in one of them.

Due to structural stability issues in the modern reproduction, we needed to disassemble the entire frieze. Once the birds were removed, it was evident that their surfaces were very grimy, related to both the burial environment and time in museum storage. A variety of cleaning methods were explored and tested, but none worked better than using our laser.

One of the birds, after removal and before cleaning

The Conservation Department purchased a Compact Phoenix Nd:YAG laser several years ago, and we are still learning about all of its possible applications. We recently had a workshop with conservator and laser-guru Adam Jenkins, which helped us further develop some testing and health and safety protocols.

Essentially, the Nd:YAG laser works like this: the laser emits a beam of light, typically with a wavelength of 1064 nm (in the infrared), which selectively irradiates and removes unwanted dirt and surface coatings without damaging the object (a process called laser ablation). This type of laser cleaning works well for removing dark substances from light-colored objects, so trying it on one of the birds made a lot of sense.

Easy for me to say. I didn’t do this treatment – project conservator Madeleine Neiman did. So she gets all the credit for this.

After testing, Madeleine carried out her first laser cleaning treatment on the bird in the image below. Here she is getting set up to carry out the work:

And here is a shot of the bird after the surface was partially cleaned: (WOW!)

I think the process and results are best displayed in a gif, or a video, so I’m including the gif below, and here is a link to the video.

Go Madeleine! I think this was a really rewarding treatment to carry out. Please take note of all of the PPE (personal protective equipment) involved, including special eyeware and ventilation.

CAAM takes over the Artifact Lab (for a day)

If you visit the Artifact Lab tomorrow (Tuesday August 22) during our open window sessions, you’ll be in for a treat. Instead of speaking with one of us (the conservators) you’ll have the opportunity to chat with two of our CAAM* teaching specialists, Dr. Kate Moore, Mainwaring Teaching Specialist for Zooarchaeology, and Dr. Marie-Claude Boileau, Teaching Specialist for Ceramics. We frequently consult and collaborate with them, but this will be their first time working behind the glass walls of the Artifact lab for our open window sessions.

Dr. Kate Moore and Dr. Marie-Claude Boileau in the Artifact Lab

They look ready for anything, don’t they? Don’t miss this unique opportunity (between 11:00-11:30am and 1:30-2:00pm) to ask them questions and talk to them about their work and research!

*CAAM, which stands for The Center for the Analysis of Archaeological Materials, is a joint endeavor between the Penn Museum and the University of Pennsylvania’s School of Arts and Sciences (SAS)

A lion relief from Nippur

Yesterday we received a new artifact in the lab: this terracotta lion relief from Nippur, Iraq.

B20014: the lion relief in fragments

Some may argue that this object could be a candidate for the Ugly Object of the Month club. Well, we like him, and one of our conservators pointed out that he looks a lot like one of these wonderful characters from William Steig’s Rotten Island.

Illustration from William Steig’s “Rotten Island”. Image courtesy of scienceblogs.com

This relief was excavated in the University of Pennsylvania’s Babylonian Expedition to Nippur in 1899. Like the Nippur slipper coffin currently on display in the Artifact Lab, it was previously repaired with metal staples and (at least one type of) adhesive, likely around the same time as the slipper coffin.

The staple-like wire tires used to repair the relief are visible in this view of one of the break edges.

More evidence of the old repairs on this fragment.

Getting this relief ready for exhibition in the Middle Eastern Galleries will not only require significant conservation treatment, but also a custom mount so that it can be displayed safely. We will provide updates as we work on this.

Update from the Gordion Excavations

Julia Commander is a third-year graduate student in the Winterthur/University of Delaware Program in Art Conservation. She is currently completing a curriculum internship at the Penn Museum.

In my last post, I introduced the Gordion Archaeological Project and what I’ve been up to as a conservation intern here. The season has continued at a quick pace, with a steady stream of incoming small finds and projects at the Gordion Museum.

While some objects only require a light cleaning, others can take a few days to process. I mentioned two pairs of copper alloy tweezers, and second pair has now been fully treated. In addition to mechanical cleaning, the copper alloy object was treated with the corrosion inhibitor benzotriazole, also called BTA. Objects are immersed in the solution and placed in a vacuum chamber to ensure effective application. The corrosion inhibitor is then protected by a coating of dilute acrylic resin. After these treatment steps, any structural breaks can be reconstructed and joined with an adhesive. For objects with weak points that may be susceptible to further breakage, small supports can be added to the housing. Here I included an Ethafoam support with a cavity cut out to hold the pair of tweezers.

Copper alloy objects are rinsed with acetone prior to treatment with BTA, a corrosion inhibitor.

Copper alloy objects drying after treatment. This group includes an arrowhead, a fibula, tweezers, and a decorative fitting.

Another example is this small ceramic figurine fragment. In this case, the female figure has a stable structure but a very delicate pigmented surface. The pigment was consolidated with a dilute adhesive mixture, applied by pipette to avoid any action on the surface. To further protect the surface, the figure was cavity packed with a layer of smooth Tyvek, which will prevent abrasion and further pigment loss.

Ceramic figurine fragment in protective housing, made from an Ethafoam cavity with smooth Tyvek barrier.

Processing small finds often involves unexpected discoveries. While working on a small ceramic vessel, I was interested to learn what was contained inside. One of the best parts about working on site is the opportunity for immediate collaboration. After talking about the soil samples with an archaeobotany student, I knew to expect small bones in the vessel interior, potentially from a mouse. After pulling out many, many vertebrae and rib bones, I consulted our zooarchaeologist to figure out what the bones may be. There were no signs of a skull, which likely deteriorated further due to its fragility. However, the other bones indicated not a mouse but a snake coiled inside the vessel. We can’t say what the snake was doing there, but all the associated bones and soil will be kept for potential further study.

Excavating the interior of a small intact jug.

Small rib and vertebrae bones, likely from a snake, from the interior of the jug.

During the season, we’ve also had some very large finds in the active excavation areas. This includes a large ceramic pithos that was found almost completely intact. In this case, conservation made several site visits to consult about techniques for supporting and lifting the object. After padding the interior of the vessel, we added supportive wrapping over a thick layer of dirt that was left as protective casing. This process helps minimize damage from physical forces and also keeps fragments in place if they happen to detach.

As I get ready to wrap up my time here at Gordion, I was lucky to have the opportunity to see the site from a new perspective. Along with several colleagues, I was able to take a hot air balloon ride over Yassıhöyük and some of Gordion’s many burial mounds.We enjoyed magnificent aerial views of our workspace!

Aerial view of the citadel mound with active excavations.

Hello from Gordion!

Julia Commander is a third-year graduate student in the Winterthur/University of Delaware Program in Art Conservation. She is currently completing a curriculum internship at the Penn Museum.

As part of my internship year, I’m spending a month at the Gordion Excavations in the small town of Yassıhöyük, Turkey. This site, the capital city of ancient Phrygia, has been excavated by the University of Pennsylvania since the 1950’s. As a student interested in archaeological conservation, gaining experience with material in the field is an exciting learning process.

The Gordion dig house.

The conservation lab within the dig house compound.

Our home base is a small lab in the dig compound, where we work on processing whatever the excavators find. This year, we have a large amount of iron and copper alloy material. The metals are corroded and fragile, but many retain interesting details and clues about their use. Some of my favorite small finds so far are these two pairs of copper alloy tweezers, including a miniature version! Cleaning involves mechanical removal of dirt and corrosion products, followed by the application of a corrosion inhibitor for the copper alloy.

Two pairs of tweezers recovered as small finds and modern tweezers for scale. The miniature pair (left) has already been treated by reducing dirt and corrosion products.

We also consistently have a lot of ceramic material. Most of the ceramics are washed, sorted, and stored as bulk pottery, although particularly significant or interesting fragments come to the lab. This category includes painted tiles, inscribed or elaborately decorated fragments, and vessels that can be reconstructed. In the lab, we set up containers for desalination treatments, where ceramics are soaked in filtered water to slowly reduce salt content. These salts came from the burial environment, and they can cause damage over time if they remain in high concentrations. The process factors in ceramic weight, water volume, and time to tailor a treatment plan for each object.

Desalination set-up. Each container holds a ceramic object or fragment, and the soaking process reduces salts in the material.

In addition to keeping up with the current excavations, the conservation team works on projects with researchers and the local Gordion Museum. For researchers, accurately recording artifacts often involves detailed measuring and drawing. Conservators contribute to the process by joining fragments and reconstructing objects so that they can be documented. We also have ongoing preservation projects at the museum to make sure that objects are stored properly and stable over time. One example is the use of silica gel, which can help control humidity in storage housings.

Working on site moves at a quick pace, but there’s still time for exploring. One of my favorite near by sites is Midas City, known for its monumental rock carvings. Visiting different sites and museums, such as the Museum of Anatolian Civilizations, helps contextualize my work and adds to the experience. There’s still more to come from this busy season!

The Midas Monument at Midas City.

Two human figurines from Tureng Tepe

Preparations for the opening of our new Middle Eastern Galleries are well underway. Take a peek into either of our lab spaces (both the Artifact Lab and our main lab spaces) and you’ll see a multitude of artifacts being treated for this upcoming exhibition.

I recently treated two ceramic human figurines which will be going into a case with several other figurines from Tureng Tepe, a site in northeastern Iran.

Map of archaeological sites in Iraq and Iran, with a red star next to Tureng Tepe. Base map image credit: University of Chicago.

One is female, and mostly complete, and the other is a male torso.

Like most objects for the Middle Eastern Galleries, both of these objects needed treatment. And they represent two different reasons for treatment, which we commonly seen in our lab.

The female figure had a couple different problems. First, and most obviously, her head was detached.

A detail of 32-41-68, before treatment.

The other problem stemmed from the fact that she had been treated before. In the 1980s, she was desalinated by soaking in water, and consolidated with PVA-AYAF, a polyvinyl acetate resin. Both of these interventions were important for the long-term structural stability of this piece. But the problem related to old treatment was an aesthetic one – there were areas on the body that were very discolored/gray, which made for a splotchy appearance overall. You can see these gray patches in the images above. These gray patches were also very shiny, and were related to a coating that had been applied to the figure at some point – possibly the old PVA consolidant.

Treatment of this figure included removing the darkened coating by swabbing with acetone, and some mechanical removal with bamboo skewers. The head was reattached with Paraloid B-72. There were some areas where the ceramic body was flaking and these areas were consolidated with a dilute solution of Paraloid B-72 in acetone and ethanol.

32-41-68 before (left) and after (right) treatment

In contrast, the male figure had never been treated. When I first laid eyes on him, I thought to myself, “Terrific! This piece looks like it will just involve documentation. It will be in and out of the lab within a day or two.” Well, looks can be deceiving, and I quickly realized that the male figure had a soluble salt problem, related to the burial environment. I actually haven’t discussed soluble salts on this blog before. You can read a nice explanation of soluble salts, how they affect archaeological objects, and what we do about them, in Tessa de Alarcon’s blogpost on the Penn Museum blog.

The most obvious signs of soluble salts were the small flakes of ceramic sitting under the figure in its storage support. A quick spot test for chlorides was positive, so I made the decision to desalinate the figure by immersion in water for several days. After desalination, I readhered the small flakes, and the treatment was complete.

Before (left) and after (right) treatment images of the male figure from the side. Small flakes were reattached in the area indicated by the red arrow.

32-41-62 before (left) and after (right) conservation treatment.

As I mentioned, these artifacts will go into a case with several other human figurines from Tureng Tepe. We have, or will be treating a number of figurines from several different sites for the Middle Eastern Galleries. I am including images of some of these figurines below. Personally, I like the ladies with their hands on their hips.

Human figures. Link to larger images and more information by clicking on their numbers (listed from left to right): 32-41-25, 31-43-450, 43-29-3, 58-4-3, 31-16-733, 31-16-734