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