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Conservation
"In marine archaeology conservation is not simply a set of procedures and treatments. Often the conservator is the first and, in the case of some very fragile items, the only person to see the actual artifact. The conservator's responsibilities are that of archaeologist, mender, caretaker and recorder of the artifacts that come into his or her care. Conservation, like archaeology, is a state of mind: a state of mind which holds a deep concern for the integrity of the artifacts and what they represent as remnants of history."- Donny Hamilton, Director of Conservation Laboratory at Texas A&M University
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This sealed wooden chest and its unknown contents, have been kept stored in an aquarium at the Texas A&M Conservation Research Laboratory.
Conservation means to preserve an object. The majority of objects recovered from the ocean need to be preserved with special chemicals. If this is not done quickly and properly the artifacts will rapidly deteriorate.
When Conservators receive artifacts they usually follow a four step procedure:
Step 1
Documentation, Conservators document artifacts by video taping, photographing and drawing them.
Step 2
Analyze the artifact, Researchers sometimes x-rays objects if they are covered by concretion. Concretion is made up of grains of sand, shells particles, coral and sea plants. This material begins to build up on objects beneath the sea as they start to rust and corrode. After awhile concretion covers the object, preserving it in a hard protective shell. Removing the concretion is a painstaking and tedious operation. Conservators X-Ray the artifact before going to work. They must determine the exsact shape of the object underneath the tough outer casing. After determining the fragility of the artifact the conservator goes to work using special tools to free the artifact from the concretion. How much concretion is built up on the artifact depends on where it was found and how long it was in the water.
Step 3
Clean the artifact When removed from the sea metal artifacts often contain salt (sodium chloride). Nautical Archaeologist, Donny Hamilton, Director of the Conservation Laboratory at Texas A&M University states "Artifacts from a marine environment are saturated with salts that must be removed when an artifact is recovered. In addition, the salt water environment accelerates the corrosion processes of many metal artifacts. If the salts are not removed and the artifacts treated in a timely manner they will, over time, deteriorate and become useless as a diagnostic or museum display specimen." The salinity content varies greatly from ocean to ocean and as a general rule the less salt the less destruction. The Vasa's artifacts were remarkably preserved because of the low salt content in the Baltic Sea. If the metal was left untreated, the salt would react with the air and the object would crumble away.
Step 4
Stabilize the artifact. Conservators clean and stabilize artifacts to protect them against having a bad reaction when removed from the water. Electrolysis is time consuming process that draws salt out of the metal by running an electrical current through it. The more salt the metal contains the longer the process takes. Artifacts are treated according to their individual material make-up . For instance porcelain, bronze and wood are all be treated differently. The conservator makes the object stable by using special chemicals and tools.
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Artifacts such as this cannon, from the Belle are usually stored in tap water with special stabilizers added to prevent further corrosion.
Photographs courtesy of the Texas Historical Commission and Texas A&M University