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SYM-106: Conservation of Archaeological Materials from Submerged Sites
Time:
Saturday, 06/Jan/2024:
1:30pm - 3:15pm
Session Chair: Chris Dostal
Location:OCC 201
Oakland Convention Center
Level 2 / Room 201
Session Abstract
The conservation of archaeological materials from submerged sites brings in unique challenges not present in terrestrial archaeological conservation. Storage, pre-treatment, conservation strategies, and curation all have to be tailored to contend with the way different materials degrade in water. Significant strides have been made in recent decades to overcome several of the more serious issues that have plagued conservators, but there are plenty of new challenges ahead, especially as more modern materials begin to fall into the archaeological record. This session is a broad forum to highlight recent developments in methodological approaches, some of the challenges facing conservators, and interesting case studies related to the conservation of archaeological materials from underwater sites.
Presentations
1:30pm - 1:45pm
Post-conservation Carbonate Blooms on a Bronze Gun from the Alamo
Chris Dostal
Texas A&M University, United States of America
In 2008, a Spanish-made 4pdr bronze cannon thought to have been used to defend the Alamo in 1836 was donated to the Alamo Museum, which sent it to the Conservation Research Laboratory at Texas A&M University for conservation prior to display. After 12 years, it began to exhibit new corrosion, and was sent back to the lab for retreatment in July of 2020. After undergoing the same conservation process as it had previously, a previously unseen white precipitate formed on the surface. Analysis of the powder showed it to be a mixture of carbonates and copper hydroxide, indicating that it was likely occurring due to the electrolyte used. To address this, a series of small like-composition ingots were put through the same process to mimic the precipitate, then various acids were tested to identify an appropriate in situ method for neutralizing the carbonate blooms without damaging the metal.
1:45pm - 2:00pm
Conserving US Navy’s Heritage
Shanna L Daniel
Naval History and Heritage Command, United States of America
Naval History and Heritage Command (NHHC) Underwater Archaeology (UA) Branch provides a unique look into the United States Navy’s history through the management, research, preservation, and interpretation of its sunken and terrestrial military craft (SMC). The archaeological material recovered from SMC sites is managed by the NHHC Conservation, Research, and Archaeology Lab (CORAL). This paper delves into the preservation and management of Navy’s archaeological collection highlighting on-going conservation projects that will help broaden our knowledge of Navy’s heritage.
2:00pm - 2:15pm
Fully Loaded: Conserving the Contents of Revolutionary War-Era Cannon
Karen E. Martindale
Texas A&M University, United States of America
In early 2023, the Conservation Research Lab began work on 17 Revolutionary War-era iron cannon and associated artifacts recovered during the Savannah Harbor Expansion Project. Many of these cannon had wood tampions concreted in place, protecting the contents in the bores. This presentation will discuss the contents and their conservation, with a focus on the paper powder cartridges.
2:15pm - 2:30pm
Conservation Observations of the Tin Ingot Assemblage of the Uluburun Shipwreck
Annaliese Dempsey1, Angela Paola2
1Texas A&M University, United States of America; 2Texas A&M University, United States of America
The Late Bronze Age Uluburun shipwreck sank ca. 1325 BCE and was excavated by the Institute of Nautical Archaeology from 1984 to 1994. It yielded a large assemblage of raw metal, including around 1 ton of pure tin in the form of ingots. Artifacts of pure tin are rare from any context, and especially from an underwater context from this period. As such, the conservation needs of pure tin from maritime contexts are not robustly understood, with some sources stating that artifacts of this type are stable and require little to no conservation beyond desalination. Processes observed in this assemblage demonstrate that the conservation needs of maritime tin artifacts are more complex than previously realized. The conservation of this assemblage is active and ongoing, and this presentation will provide an overview of observed changes in the tin ingot assemblage as well as possible underlying causes.
2:30pm - 2:45pm
Physical Characteristics, Including Digital Models, of Seventeen Revolutionary War Cannons from the Savannah Harbor Expansion Project (SHEP)
Alyssa M Carpenter
Texas A&M University, United States of America
A total of nineteen cannons were recovered from the Savannah River during the Savannah Harbor Expansion Project (SHEP) in 2021. It had been assumed that these cannons were from a British scuttled ship during the American Revolutionary War in 1779. Seventeen of these cannons were later transported to the Conservation Research Lab (CRL) at Texas A&M University. Physical characteristics (such as markings and reinforcement band patterns) have been revealed during the conservation process. Each of the cannons were laser scanned and 3D modeled to digitally preserve and document their condition. These characteristics could indicate foundry manufacturer, country of origin, weight, age, or identification number. Preliminary analysis indicates an inconsistent blend of cannon types from this site. While all the cannon are 6-pounders, there is a variety of markings, weights, lengths, band patterns, and ages. This paper will discuss these physical characteristics to provide a holistic analysis of the collection.
2:45pm - 3:15pm 15min presentation + 15min break
Addressing Iron Sulfate and Sulfuric Acid Generation in Artifacts Treated with Silicone Oil
Kimberly L. Breyfogle
Texas A&M University, United States of America
The generation of iron sulfates and sulfuric acid in submerged organic artifacts was originally recognized in the early 2000s and has been the subject of research and concern since then. Initially thought to be the result of iron contamination interacting with PEG, it is now evident that the problem is not limited to artifacts treated with PEG. Recent analysis of degradation products from a 17th century gun carriage treated with silicone oil has revealed that the artifact is suffering from the same process. Subsequently, research has begun on whether such artifacts will respond to traditional chelation treatments and how the treatments affect both the artifact and the silicone polymers embedded within it.
