Cannon Preservation Project


Project Update

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Preserving the Past

On June 7, 2018, the first phase of a multi-year cannon preservation project began at Castillo de San Marcos National Monument. Through a partnership with Texas A&M University, 25 iron cannons will receive treatments to protect them from on-going corrosion from exposure to the elements. This project will be on-going over the next 5 years. In Phase One, 14 iron cannons from Castillo de San Marcos National Monument were removed from the fort and transported to the Conservation Research Laboratory at Texas A&M.


Your Fee Dollars at Work

This partnership project with Texas A&M University is funded by park entrance fees collected at the Castillo. These funds help the National Park Service care for the historic structures, museum collections, and other critical maintenance projects necessary to preserve these special places for generations to come.


Where are the Cannons Going?

The cannons that are being removed from the park are being sent to the Conservation Research Laboratory at Texas A&M University to be conserved. These cannons are made of cast iron, which is particularly prone to electrochemical corrosion due to chloride contamiation. The chlorides come from airborne salts (NaCl) and must be removed from the porous metal to stabilize the cannons and prevent future corrosion.

Upon reaching Texas, the cannons will first be mechanically cleaned using pneumatic scribes to remove superficial corrosion and to clear out the bore. Then, each cannon will be submerged into a vat of caustic electrolyte and fed a negative DC electrical charge. This electrical charge will reduce and remove the corrosion materials and drive out the chlorides, stabilizing the iron.

When all of the chlorides are removed from the iron, the cannons will be boiled in a bath of de-ionized water. From there, they will receive several coats of tannic acid to form a corrosionresistant barrier before being sealed up with a special type of corrosion-resistant paint. Once the treatement is complete, the cannons will be shipped back to St. Augustine and re-installed at the Castillo.

Last updated: June 23, 2020

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Contact Info

Mailing Address:

1 South Castillo Drive
Saint Augustine, FL 32084


904 829-6506

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