Importance of Electrolysis

October 13, 2017

Next in our student series is Robert (Austin) Masters. He writes about his project conserving iron artifacts through electrolysis.

Importance of Electrolysis

Last semester I was fortunate to take Professor Seifert’s Historical Archaeology class at Armstrong State University and participated in digs at the Benedictine Monastery and Freedmen School site and the Sorrel Weed House. When I first registered, I was not sure if I would enjoy the class. After the first couple of classes and digs, I knew that I was interested in archaeology and wanted to do more.

At the very end of last semester, John Roberson, our consultant, set up an electrolysis system in the anthropology lab. The main reason that we perform electrolysis is to preserve metal artifacts. This process stops the oxidation in the artifact. Once we had the machine up and running, I wanted to help preserve some of the iron artifacts discovered at the Benedictine Monastery and Freedmen School site and the Sorrel-Weed House. These items include possible door hardware, a piece of a knife, springs from a mattress, and other iron objects. I am doing this project because preservation of artifacts is something that has interested me, and without the use of electrolysis, iron artifacts will continue to rust and will eventually turn into dust. By preserving these artifacts, it will allow us to study them and understand what they were used for and how they were used in the past.

Electrolysis is used to preserve metal artifacts that have exposed to salt, either in the water or in the air. In simple terms, electrolysis is an oxidation reduction reaction. In the Armstrong lab, we have a simple plastic tank that can be found at many hardware stores. The tank contains the artifacts, which are connected to the negative side of the power source. The anode, which is a piece of iron rebar, is connected to the positive side of the power source. Both the rebar and artifacts are in a bath of electrolytes (water and Sodium Carbonate, Na₂CO₃). The length of time artifacts stay in the tank depends on the size and corrosion of the artifacts. Smaller artifacts may only stay in the tank for few weeks, while a cannon could take months to years to ensure the preservation of the artifact. Once the electrolysis is complete, the artifact is coated in epoxy to form a barrier between the artifact and oxygen. After electrolysis and coating, the artifact can either be placed on display in a museum or placed in a depository for further research down the road.