Conservation Lab: Preserving the world’s oldest objects

Editor’s Note: This is part of a new series called Inside the Lab, which gives audiences a first-hand look at the research laboratories at the University of Chicago and the scholars who are tackling some of the world’s most complex problems.

Deep inside the Institute for the Study of Ancient Cultures—past cases filled with cuneiform tablets and giant stone sculptures that guarded the temples of long-dead kings—is a very modern laboratory. In it, a team of highly trained conservators, armed with tiny brushes and large microscopes, work diligently to preserve these pieces of cultural heritage for the future.

Since 1974, the Conservation Laboratory at ISAC (previously the Oriental Institute or OI) has helped care for thousands of objects from West Asia and North Africa—a region home to some of the world’s oldest civilizations.

The lab specializes in caring for archaeological materials, or things that have been buried for up to thousands of years. Over time, buried items can be physically and chemically damaged by environmental factors like insects, water and soluble salts. Even human conflicts can put archaeological artifacts and sites at risk.

When they are excavated, artifacts may be in pieces or partially disintegrated. That’s where conservators step in. These experts use their in-depth knowledge of art history, materials science and chemistry, as well as steady hands and extreme patience, to prevent further deterioration.

We spoke with conservators Laura D’Alessandro and Alison Whyte to get a behind-the-scenes look of the important work that happens inside the lab. 

What does a conservator do?

Whyte: In the broadest sense, a conservator is responsible for the preservation of a collection of cultural heritage. Some conservators specialize in paintings, some train in paper-based materials and some focus on 3D objects. The conservation of archaeological materials is a sub-specialty of object conservation.

No matter what the specialty is, our major focus today is on preventive conservation. We try to control the environment that houses an artifact—whether it's storage or display—to try to prevent, or slow down, decay processes.

How does someone become a conservator?

Whyte: A graduate degree from a recognized conservation training program is required for most professional conservator positions. There are only a handful of training programs in North America, and competition for admission can be fierce.

Once admitted, students select a specialty (paintings, paper, or objects) and complete coursework in a variety of subjects including technology and manufacturing methods, materials science, analytical techniques, documentation, ethics as well as hands-on training in conservation treatment.

What happens in the Conservation Lab?

D’Alessandro: Hundreds of objects come through the lab each year for a conservation assessment to determine their readiness to go on exhibit, on loan to another museum or their ability to be safely handled by visiting researchers. 

Whyte: We spend a lot of time figuring out and maintaining the optimal relative humidity and light levels for artifacts. We carry out treatments on objects when necessary, including cleaning, stabilization, repairs and reconstructions.

D’Alessandro: Despite creating an optimal environment for the objects, there is a certain percentage of the collection that continues to corrode or deteriorate. Those at-risk objects are our highest priority.

What kinds of objects have ISAC conservators worked on?

D’Alessandro: In the 1990s and early 2000s, large-scale Assyrian reliefs were removed from the walls of their 1933 location, stabilized by conservators and placed in steel frames to make them “easily” movable. 

The reliefs were then placed in their current configuration to form the recreation of Sargon’s palace that can be seen in our galleries today. 

Another major project involved the relocation of our statue of Tut. It was too tall to be removed in one piece and had to be cut in half (through an area of restoration!) in order to be moved to its current location.

What’s a project you’re working on in the lab right now?

Whyte: Currently, we are conserving a collection of 282 glazed baked clay bricks that formed one of two facades that stood on either side of the entrance to the eighth century B.C.E. Sin Temple at Dur-Sharrukin, which is in modern-day Khorsabad, Iraq.

The bricks have a multicolored glaze decoration that shows different figures and symbols in a procession leading towards the entrance. There are human figures, a plow, a tree, a bull, an eagle and a lion. There are different colors—a blue background as well as details added in white, black and yellow glaze.

How did the bricks come to ISAC?

D’Alessandro: The French first excavated at the site of Khorsabad in the mid-19th century. Then, in 1929, ISAC (the former Oriental Institute) received permission to excavate the site from the Iraqi government’s Department of Antiquities.

When archaeologists uncovered the facade of the Sin Temple, still intact in its original position, they realized the importance of this amazing find.

As per the division of finds determined by the Iraqi government, the more complete right side of the frieze went to the National Museum in Baghdad. We were given the left side, which was more fragmentary.

The bricks were packed very carefully on site. The excavators took photographs of the frieze and labeled each brick in the photos. The brick numbers were written on each crate (over 40 crates!) as the bricks were packed.

How do you go about conserving bricks that have been packed away for almost 100 years?

Whyte: The bricks are so fragile that when they first come out of the crate, there are lots of loose pieces. It takes a lot of patience and time to do it properly.

We've developed different methods to create temporary support to transfer the brick to a bench where we can continue the stabilization process under the microscope if necessary.

Stabilization can involve cleaning to remove any residual dirt from burial, consolidation and repairs. Consolidation essentially means applying a low concentration of an adhesive to the surface to try to make it stronger.

Ultimately, it's very rewarding once you can get all those separate fragments back together. They're not going to look like they haven't been broken, but we can at least put them back together in a way that you can appreciate what they might have originally looked like.

How much do you have left to do?

D’Alessandro: We still have around 28 crates to open, each containing eight bricks. The unpacking, conservation and reconstruction of the frieze is at least a two-year job, with additional conservators needed to carry out the work.

We are currently sharing a postdoctoral position with the Field Museum in Chicago, focusing on 3D imaging.  

The ultimate goal is to display the frieze in the galleries at ISAC. There are also plans for a 3D version at the Field Museum, which will make it available to a lot more people. And the digital version will be made available online. The future is really promising, and we're at a very exciting stage of this project.

Why are the bricks important?

D’Alessandro: We are so fortunate to have this incredible piece of cultural heritage from the time of Sargon II. Even though the bricks are damaged, we have an entire façade, which is unbelievable. The fact that we will be able to recreate this frieze, after thousands of years, is amazing!

It's also important because, due to wars and changes in government over time in the region, ours is the only frieze that possibly still exists.

Why is the work happening in the Conservation Lab, and beyond, so important?

Whyte: The museum at ISAC houses one of the most significant collections of archaeological material from West Asia and North Africa. Our goal is to make this collection available not just to researchers and specialists, but also to our museum visitors through our galleries and exhibits.

D’Alessandro: We are the caretakers of a remarkable part of the world’s cultural heritage here at the University of Chicago. And it's an amazing resource for people locally, as well as researchers from all over the world. Our museum is often called the secret jewel of the South Side of Chicago, and it’s here in our backyard.