H.L. Hunley submarine on the transport barge immediately following
its raising from the sea floor.
The submarine H.L. Hunley represents one of the most complex composite structures ever recovered by an archaeological team. At this point, only the exterior of the submarine has been extensively analyzed. The exterior hull is comprised of wrought-iron plates of various sizes, several cast-iron fittings and glass view-ports. The excavation of the interior has produced a large number of artifacts taken on board by the crew including navigational instruments, paper, clothing and personal items. In
addition, the presence of human remains trapped in this 'iron tomb' has made the conservation of the H.L. Hunley a unique and somewhat daunting task. All actions undertaken on the submarine have been balanced and controlled so that the impact on the fragile artifacts and organic remains is minimized.
Conservation is extremely important in the field of underwater archaeology. The uncontrolled exposure to air of any material recovered from a marine environment can lead to irreversible damage and the disastrous loss of archaeological data. Iron artifacts in particular are susceptible to rapid deterioration when exposed to an oxygen rich environment. Moreover, chlorides from the seawater penetrate the iron on the molecular level. When in solution, these chlorides present no real problem. However, when exposed to air, they slowly dry in crystal form. As the crystals grow, the surface of the metal will expand and flake away, eventually reducing the artifact to a pile of iron oxide dust. Similarly, organic materials will literally collapse upon drying in a matter of days. These reactions are due to a sudden break in the equilibrium reached by the artifact after years of submersion. The main goals of conservation, therefore, are to provide archaeologists with the proper tools and techniques to handle, store, stabilize, and study the recovered artifacts.
Claire Peachey and Paul Mardikian working on the Mark’s Tide during
the excavation of the submarine.
Unfortunately, the stabilization of marine artifacts is often an expensive and time-consuming endeavor. The duration of the conservation work on the H.L. Hunley and its associated artifacts is anticipated to take seven to ten years before they can safely be handed over to an exhibition facility. The conservation process includes: a pre-excavation study, interior excavations, long-term stabilization of the vessel and interior artifacts, and a study of the human remains by a forensic team from the Smithsonian Institute before reburial.