Dr. Raymond Hayes (left) and Head Conservator George Schwarz examine p-XRF data taken from a Civil War-era Aston pistol recovered from USS HOUSATONIC at the Underwater Archaeology & Conservation Laboratory.
NHHC volunteer, Dr. Raymond Hayes, Professor Emeritus at Howard University, Washington DC, and Woods Hole Biological Laboratory, Woods Hole, MA, has partnered with the Underwater Archaeology & Conservation Laboratory (UACL) to analyze archaeological materials from historic naval shipwrecks.
Dr. Hayes has been awarded a Research & Discovery Grant from Olympus INNOV-X to examine archaeological components from shipwrecks using an innovative Delta portable X-Ray Fluorescence (pXRF) unit. This state-of-the-art technology uses an x-ray beam to identify the specific elements present within archaeological material. Dr. Hayes’ research endeavors to use this data to trace the elemental composition of a wood sample back to original construction materials, marine sediments, and sealing or fastening materials applied to wooden ships. Included in the study are data from USS Housatonic, USS Tulip, and CSS Alabama, as well as recently recovered artifacts from the 2011 USS Scorpion field project, the archaeological investigation of a Patuxent River shipwreck believed to be the flagship of the Chesapeake Bay Flotilla, which fought to defend Washington D.C. from the British during the War of 1812. As part of the Navy’s commemoration of the Flotilla’s important role in the War of 1812, a full excavation of the USS Scorpion site is anticipated.
Scientific technologies like pXRF provide archaeologists and conservators valuable chemical information that can be used to better conserve and interpret submerged cultural heritage. An innovative feature of pXRF devices is that they can be used in both the laboratory and the field to analyze artifacts recovered from wet environments. Artifacts from underwater sites can be difficult to initially identify as they may be encased within thick concretions or obscured by unidentifiable corrosion products, however, pXRF data can give archaeologists data which can signal the presence of an artifact.
Detail of portable X-Ray Fluorescence machine collecting data from Civil War-era pistol.
Following recovery from underwater archaeological sites, artifacts are particularly susceptible to damage caused by soluble salts (e.g., chlorides) accumulated from the water or sediment that surrounded them for decades or even centuries. If allowed to crystallize, the salts expand and cause catastrophic damage which may result in complete destruction of the artifact. Data from pXRF can determine the concentration of chlorine within an artifact to help conservators understand the degree of salt contamination and mitigate it properly. During conservation, pXRF can help conservators develop the most optimal treatment plan for artifacts and reveal the presence of toxic components, such as lead, cadmium or arsenic. Comparative data may also reveal similarities or differences in artifact composition that could suggest age and geographic origins.
This is only one part of the extensive research that goes on at the Underwater Archaeology & Conservation Lab, where over 2300 artifacts recovered from US Navy shipwrecks and aircraft wrecks are curated, 140 of which are currently undergoing active conservation treatment. The Laboratory, located in BL 46 of WNYD, also hosts public tours showcasing important artifacts that span from the American Revolution to World War II and make the Navy’s history come alive! Please feel free to contact us anytime (202.433.9731) if you’d like to visit!
For more information about the NHHC Underwater Archaeology Branch and the Underwater Archaeology & Conservation Laboratory, please visit http://www.history.navy.mil/underwater.