The MAC (Maryland Archeological Conservatory) Lab
, located at the Jefferson Patterson Park and Museum
, curates artifacts from over 90 sites within the Park and stores over 8 million artifacts collected from sites throughout Maryland. In the lab we were able to tour all of the Conservation and Treatment facilities and have an inside look at what artifacts were being preserved to be put on display or used in research.
We learned how cleaning the artifacts and preserving them correctly when they come out of a “dig” (whether it be in the ground or in the water) can affect their condition and long-term stability. The best examples shown to us were two cannons we saw at the beginning of the tour. The first was a cannon from Fells Point at Baltimore Harbor; it was taken out of the water and allowed to dry with no further treatment. After years in saltwater, this cannon had many chlorides within the metal. Upon drying the chlorides crystallized and loosened the outer surface of the cannon. By the next day any markings that could have provided archeological information about the cannon, such as where the cannon was made or who owned it, had disappeared. We then examined a second, properly preserved cannon. All its surface markings were intact. It goes to show you that when it comes to artifacts, you have to be careful how you remove them from a site. Once you do, you must immediately try to conserve them properly, or you’ll loose what is needed for research or identifying the artifact.
Cannon recovered from Baltimore Harbor near Fells Point
Artifacts being preserved can take as short as a few weeks or as long as a few years to conserve. The length of time necessary largely depends on the material the artifact is made of. The conservation process is done in three steps: The first step in preservation is to desalinate the artifact by soaking it in water or basic solution. This removes any salts or chlorides from the artifact, which was not done to the first cannon and therefore resulted in a loss of markings. Once the artifact is cleaned, it is put into a vacuum freeze-dryer, if it is an organic material such as wood. The vacuum freeze-dryer at MAC was 12 feet long, and at the moment, we were able to see a piece of palisade timber inside it. We were told that the timber was cleaned off and then placed in the dryer after soaking in PEG (Polyethylene Glycol). As the water from the timber is removed by sublimation, the PEG holds the shape of the timber in place and keeps it from becoming distorted. After the artifact has been cleaned and stabilized, it is pieced together or mended, if required. For example, a Native American pot we saw was being pieced together with an adhesive that is a mixture of B72 and acetone.
This Native American clay pot is being reconstructed at the MAC Lab.
The process of conserving artifacts is so intense and carefully done that I was nervous at times when I was handed the stuff to look at because I was afraid of dropping it. It fascinates me so much though, that we can piece together so much of the past with the advanced technology that we have.
Also today we hiked to Calvert Cliffs while enjoying the site and identifying trees. We identified American Holly, which really reminded me of Christmas time. We laughed when Kimmy put the American Chestnut leaves in her hair; she looked like the Tree Queen. On the way down to the beach, at the end of the hiking trail, Katie found an eastern wormsnake. She at first thought it was a worm, which she hates, but after looking closely she realized it was a baby snake. It was dark colored on top and had a very orange underbelly. When we arrived at the beach, it was slightly unpleasant due to the land breeze that was blowing at us, sending swarming biting flies our way. We didn’t stay there too long . The hiking trail we took was a total of 1.8 miles, uphill and downhill, and it was muddy and slippery at times. Overall, it was a beautiful day and I had a good experience touring the lab and taking a stroll in the park.
Here is our group at Calvert Cliffs State Park.