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Conservation of USS Monitor artifacts is a slow, meticulous process

Posted on Sunday, July 2, 2017 at 12:13 am

It has been over 14 years since the turret of the USS Monitor returned to Hampton Roads from its watery grave off the North Carolina coast. Since the day after it arrived on a barge – August 5, 2002 – the turret from the iron warship has been on the grounds of The Mariners’ Museum in Newport News, Virginia. Originally, the plan for the Monitor Project called for bringing up 30 tons of the famous Federal warship that fought the Confederate ironclad CSS Virginia to a draw in Hampton Roads in March of 1862. Currently about 130 tons of Monitor artifacts are undergoing some form of conservation on museum grounds. The objects being processed include the turret, guns and carriages, five engines, and most of the vessel’s engine room. Processing historic relics on that massive scale has been a formidable challenge for staff members charged with the seemingly impossible task. Conservators are taking the hurdles that accompany that challenge in stride.

“In these projects, you can do the time lines and estimate as best you can, but at the end of the day, you’re working at the rate of your resources,” said Will Hoffman, senior conservator with the Monitor Project. “You have to constantly re-evaluate and re-address the plan every couple of years,” he said. “If you don’t hit your targets, the work goes slower than anticipated, and you’ve tacked on two years.”

Will Hoffman has been with the Monitor Project for seven years. When he arrived at the museum staff members were dragging hoses around the outside treatment tanks and wrapping heat blankets around them. Conditions at the Monitor Center have changed considerably over the last five years. When people from other museums with similar marine conservation projects underway ask about progress on the turret and other artifacts, Hoffman tells them that the museum is kind of in “the middle of the project.”

Over the last couple years, the museum has been actively engaged in figuring out the funding situation. That, according to Hoffman, was really remedied last year.

“The partnership between the museum and NOAA is stronger than it has been before,” said Hoffman. “We’re in a good place so we’ve really started working toward the big picture and where we stand with Monitor and what the future of the project is going to be.”

Although some of the conservation techniques used in treating one or two objects – such as artillery pieces – are very similar to those used in the conservation of the tons of Monitor artifacts, the enormous scale of the Monitor Project makes it unique.
“One of our big challenges has ultimately been space,” said Hoffman. “We just redid the whole electrical-chemical system that we were using to conserve the turret,” he noted. “One of the next big steps will be doing a new form of cleaning to remove the corrosion. We also have to take the roof off of the turret.”

Right now the turret is still upside down, as it was when it first arrived on the barge that transported it from the Graveyard of the Atlantic to its current home at the museum. The turret consists of 192 wrought iron plates. The inch-thick iron plates are 3 feet by 9 feet. There is an overlapping area of 8 inches. The iron plates are fastened together by rows of 2 ¼-inch round-head rivets. Originally, conservators had planned to take the iron plates completely apart and treat them to remove the ocean salts – chlorides – via an electro-chemical treatment. That would have required cutting the iron rivets, separating the plates, treating the plates individually, and reassembling the 20 ½ -foot in diameter turret.

“Our decision has been made to leave the turret together. We’ll do the best we can to desalinate it,” said Hoffman. “There’s a possibility that we’ll never get all the chloride out.”

Concern that ocean salts trapped between the wrought iron plates would lead to massive corrosion if the turret were electro-chemically treated intact initially suggested that separating the plates would be the best course of action. Anxieties related to the difficulties that might have occured in reassembling the turret after conservation have caused conservators to reconsider their plan to dismantle the turret entirely.

“If you don’t remove the chlorides, you can get a really bad voluminous form of corrosion … crumbling iron due to ocean salts,” said. Hoffman. “That’s why if artifacts are brought up from a saline environment and are not treated, they ultimately will fall apart,” he explained. “The time period that it takes to desalinate artifacts really varies.”

Another major challenge facing project conservators is the treatment of composite artifacts. The gun carriages and engines are prime examples of artifacts that are composed of a variety of materials. Different kinds of materials – cast iron, wrought iron, brass, and bronze – require a slightly different method to preserve them. The chloride concentration in the solution in which the articles are submerged is monitored via ion chromatography to determine when an artifact is desalinated. Chlorides are extracted over time. The chloride content of the solution gradually diminishes until it reaches a phase where no more salts can be extracted. That’s when conservators decide that the artifact has reached a point that it can be dried.

“Now with the engine, it’s got a low chloride content, relatively low, but we haven’t taken it apart,” said Hoffman. “Once we pull the cylinder head off, we may have thousands of parts per million in chloride coming out from inside the cylinder that you previously didn’t have access to.”

The Mariners’ Museum has five of the ship’s stream engines. They have the main engine and the two engines that drove ventilation fans. They also have two auxiliary pumps made by a company called H.R. Worthington. The pumps were primarily used for auxiliary boiler feed, but they were also used for firefighting and other purposes.

“They’ve been undergoing conservation for several years,” said Hoffman. “They have what are called pop-in valves – basically a rubber valve that moves up and down on the spring,” he explained. “We have two pumps. During conservation we took them apart. We undid the valve assembly. It’s called the spindle,” he noted. “The spring sits underneath the spindle and a rubber disk moves up and down.” Other conservators on other projects have done similar work. Hoffman and his associates research known techniques and apply them to their specific conservation work. If a method proves to be successful, they use the method as is. If it doesn’t, they have to redevelop, augment, or completely develop a new technique to allow them to do the conservation work. “We have to capture all the information that we can. We only get one shot at it,” said Hoffman. “We really want to make sure that we’ve done as much planning and preparatory work as possible.”

To do conservation right, according to Hoffman, the conservator really has to understand three things – how the artifact was made, how it was used, and how the burial environment affected it. The combination of all the informational specifics allows the conservator to make a holistic assessment of the object and its current condition. The turret was moved into active conservation treatment in 2010 when the reverse osmosis system was installed. Recently, the electro-chemical system was redone to optimize the work in progress.

“It’s a preparatory phase that we’ve installed to help loosen surface corrosion,” he said. “Then we’re going to hit it with a new dry ice cleaning system,” he said. “Hopefully that will remove more corrosion, expose more surfaces, and free more of the trapped ocean salts.”

During the next five years, Hoffman plans to make significant progress in some major aspects of the project. He hopes to have one of the Dahlgren guns with its associated carriage finished. He hopes to remove the turret roof and see major advances on the cleaning of the turret. He plans to have the Worthington pumps complete in their conservation. As the Monitor Project has moved forward, sufficient lab space to treat all the project artifacts has been a limiting consideration. The components from the engine room – bulkheads, floors, railings, and engines – are stored in a secondary facility because there is insufficient space in the lab itself. When treatment has been completed on an artifact in the lab – a gun carriage or turret or an engine – it frees up space to advance treatment on another artifact.

“We can’t take everything apart tomorrow because we don’t have room in the lab. All the tanks are full,” said Hoffman. “We can’t really – to be honest – work any faster than we’re going. Just to do the work that we just did on the turret took 2 ½ months,” he said. “We were just in the turret doing some major excavation work from May through the middle of July.”

-By Bob Ruegsegger