At the Core of the Problem: A Bespoke Method Used to Clean the Bores of USS Monitor’s XI-Inch Dahlgren Shell Guns

ABSTRACT When the turret from USS Monitor (1862) was recovered in 2002, it still contained the ship’s primary armament: two XI-Inch Dahlgren Shell Guns. These guns are the largest caliber smoothbore, cast iron artillery ever recovered from a marine archaeological site, and as a result of their size, weight, and fragile condition they represented a particular engineering challenge to clean. After comparing equipment used by other conservation laboratories to clean artillery bores, it was found that no existing method ideally fitted the predicted requirements set out for the guns from USS Monitor. As such it was necessary to create a new method to remove concretion from within the ship’s artillery, in order to facilitate their future stabilization and treatment. This article describes the reasoning behind the decision to create a bespoke treatment methodology, details the equipment designs and construction, and provides a case study for its operation.