Artifact Corner: Battle of Plattsburgh Edition – Grape Shot

Hi Everyone, and welcome back to a special Battle of Plattsburgh edition of our artifact corner series. Today we will be looking at a 24 pound grape shot from the naval engagement on September 11th, 1814. Grape shot is a series of smaller metal balls tied around a metal post, held in place with cloth and rope. When it’s fired from a cannon it breaks up and the smaller balls scatter, almost like a shot gun. This type of shot is designed to be antipersonnel, not to sink a vessel. Both the American and British forces used grape shot during the battle, so, it’s hard to say which side these came from.

These pieces have been brought up from the bottom of Lake Champlain, and carefully conserved by the Lake Champlain Maritime Museum. Let’s learn a bit more about how you conserve metal when it’s been underwater for over a hundred years. When a metal artifact has been under fresh water for hundreds of years, it is likely going to be covered in rust. The first step in conserving the artifact is to remove all of the rust. A very reliable method for removing rust is electrolysis. The iron piece is submerged in a tank of water with a measured amount of sodium carbonate in it. Then a positive electrical current is run through a piece of wire grate, while a negative electrical current is run through the artifact. The charge will then slough the rust off.

Once all of the rust is removed from the artifact, it’s time to remove any other impurities on the piece. It’s time to rinse the artifact in deionized water, and then you will need to put a protective layer over the artifact. Tannic acid is applied to the artifact, and it reacts to the iron oxide converting it to iron tannate, which forms a protective barrier over the piece. The last step is to create a seal over the iron artifact that will prevent moisture from creating more rust, therefore further damaging the piece. One of the best ways to do that is to seal the piece in a microcrystalline wax. Now your artifact is conserved and will last far longer than if the piece had not been treated.

The shot and post are in fantastic condition thanks to the conservation lab at the Lake Champlain Maritime Museum. They are also able to conserve other types of metals and wood, but the process for each material is different. If you’d like to learn more about the conservation lab, head on over to their website, for more information. We’d like to thank the Marine Research Institute for all of the help in making this special series possible. If you enjoyed this series, check out the rest of our videos commemorating the Battle of Plattsburgh, and as always, thanks so much for stopping by.

Music: Acoustic Breeze by Benjamin Tissot