Horizontal Surface Repair and Stabilization
The Castillo de San Marcos has been under assault since its construction started back in 1672. Aside from attacks by cannon and musket fire, the fort has also been battling Florida’s destructive climate, including powerful hurricanes and tornadoes, unrelenting heat and humidity, and corrosive salt air.
In addition, inappropriate repairs have occurred utilizing modern day cements, such as Portland, which are chemically and physically incompatible with the original coquina stone. For these reasons, combined with the 3,500 visitors storming through on a busy day, the Castillo de San Marcos has been steadily deteriorating.
The horizontal surfaces, in particular, have suffered damage to a level that requires immediate attention. Individual coquina stones have disintegrated and mortar joints have failed. This has resulted in the surface becoming irregular and has created 'battle scars' where water collects and vegetation takes hold.
The NPS Historic Preservation Training Center (HPTC), Park staff, NPS Southeast Regional Office, and the State of Florida Historic Preservation Office worked together to draw up a battle plan to stabilize the Castillo, one of our nation’s greatest treasures.
The preservation crew is inspecting all of the coquina which comprises the top level of the inner and outer fort walls. Poor condition stone is being replaced with healthy coquina. In addition, any previous repairs made with modern cements are being carefully removed and replaced with historically accurate lime mortars.
It is important to note that the work is not being preformed to improve the visual appearance of the fort. Coquina stones are only replaced in cases were it is absolutely necessary in order to preserve and protect the Castillo de San Marcos for future generations.
The deteriorated coquina is being replaced by stone taken from a location near where the fort’s original coquina was quarried. In addition, compatible lime mortar is being used for the bedding, pointing, and finishing of the stones.
Currently in its final phase, the project is estimated to be completed in May 2008.
Did You Know?
Black, or gun, powder is a mix of potassium nitrate, sulfur, and charcoal used as a propellant charge in cannons. Burning rapidly when ignited, it expands 600 times its volume creating pressures that can hurl a cannonball up to 3.5 miles! Castillo de San Marcos National Monument, Florida