Cannon Preservation Project


Preserving the Past

On June 7, 2018 the first phase of a multi-year cannon preservation project will begin 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 will be removed from the fort and transported to the Conservation Research Laboratory at Texas A&M.


For the safety of the public, the fort will be closed on June 7 as cannons are removed from the gun deck by crane. Additional grounds closures will be in place along the sea wall directly east of the Castillo.

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 be re-installed.

Last updated: May 22, 2018

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Mailing Address:

1 South Castillo Drive
Saint Augustine, FL 32084


(904) 829-6506

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