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CONSERVATION RESEARCH LABORATORY REPORTS COMPOSITE WOOD/IRON ARTIFACTS:
LA SALLE SHIPWRECK PROJECT,
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CONSERVATION RESEARCH LABORATORY REPORTS COMPOSITE WOOD/IRON ARTIFACTS:
LA SALLE SHIPWRECK PROJECT,
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Throughout each year, the Conservation Research Laboratory conserves material from a number of different archaeological projects. The purpose of these CRL reports is to showcase the conservation procedures used to treat some of the more interesting archaeological material. The conservation of a partisan found on the Belle is presented in this report. The Belle, one of the ships of French explorer Robert Cavelier, Sieur (Lord) de La Salle, was lost in Matagorda Bay, Texas in 1686. It was excavated by the Texas Historical Commission.
CONSERVATION OF AN IRON BLADE
Radiographs (right) of encrusted metal artifacts, such as the partisan
(below), can reveal where sound metal remains, as well as show areas of metal that have since corroded. It
is sometimes difficult, however, to determine from the X rays if the corrosion products are solid or if they are
merely loose slush. To find out, the conservator has no choice but to break open the encrustation.
If all that remains is loose slush and a natural mold of the artifact, the mold can be easily cast in epoxy.
If the corrosion products are solid, a different tactic must be used. |
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When the encrusted partisan (above) was broken in half, we realized that the corrosion products were, in fact, solid. Our original plan of casting the entire piece had to be slightly modified.
After the broken encrustation was fitted back together, it was pressed into a box containing plaster-of-Paris (below left). The plaster supported the back half of the encrusted piece, while the conservator slowly removed the encrusted top half. The conservator used an S.S. White Airbrasie unit to cut through the encrustation (below right). The precision of this tool ensured that the thin cutting edge of the partisan blade would not be inadvertently destroyed.
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After cutting off the top surface of the encrustation, all of the
metal corrosion layers were removed. Special care was taken to clean the sharp edges of the blade. Hysol
LE-6329 NA epoxy (no longer available) was poured into the open areas, making sure it flowed along the edges. The
different pieces of the top encrustation were then placed on top of the epoxy, so that it would pick up the natural
surface of the original blade surface.
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Part epoxy/part metal partisan removed from the encrustation |
Silicone rubber mold made of part metal/part epoxy partisan |
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Part metal/metal oxide and part expoxy partisan as removed from the encrustation after filling voids with epoxy |
Silicone rubber mold cast with Hysol LE 6329 NA epoxy |
After the epoxy set, the cast was removed and covered with a coating of graphite to give it a metallic appearance (right). There is additional work to be done on the metal straps that project from the partisan, connecting it to the shaft. |
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SEE HOW WE CONSERVED THE WOOD SHAFT
FIND OUT MORE ABOUT POLE ARMS AND PARTISANS
Donny L. Hamilton
1998, Composite Wood/Iron Artifacts: Pole Arms - Partisans,
Iron Blade Conservation, Conservation Research Laboratory Research Report #2a, World Wide Web, URL, http://nautarch.tamu.edu/crl/Report2/polearm1.htm,
Nautical Archaeology Program, Texas A&M University, La Salle Shipwreck Project, Texas Historical Commission,
Austin, Texas.
E-mail:dlhamilton@tamu.edu
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CRL PROJECT REPORTS |
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LA SALLE SHIPWRECK PROJECT |
The contents of this site - text, images, and data - are intended for personal information only. Downloading of information or graphic images contained herein for private use is not discouraged; however, written permission from either the Nautical Archaeology Program or the Texas Historical Commission is required for the publication of any material. Any use of this information should credit the Nautical Archaeology Program. For additional details, contact Donny L. Hamilton (dlhamilton@tamu.edu).
