A sunken 16th-century British warship that was once the pride of King Henry VIII’s fleet is getting a high-tech touch-up — with help from microscopic magnets designed to preserve the ship’s once-waterlogged wood for generations to come.
A gel containing the magnetic nanoparticles — each about 1,000 times smaller than the thickness of a sheet of paper — will be applied to sections of the Mary Rose as a way to neutralize iron atoms in the ship's wood that would otherwise form highly destructive acids.
Preliminary tests of the gel on bits of oak that had been soaked in an iron solution showed that the process was 85 percent effective at removing iron particles.
“It’s kind of a simple idea, so it’s been nice that it has really worked,” said Serena Corr, a University of Glasgow chemist and the leader of the magnetic nanoparticles project. She said the scientists are now poised to test the treatment on wood samples from the Mary Rose itself; if that goes well, the gel could be applied broadly to damaged portions of the ship's hull.
The Mary Rose sank in 1545 off England’s southern coast during the Battle of the Solent, a skirmish with the French fleet of King Francis I. The ship was raised in 1982, with about 40 percent of the structure surviving. But after more than than 430 years underwater, the Mary Rose was in bad shape — its wood eaten away by marine bacteria.
When marine bacteria feed on submerged wood, they release a chemical that reacts with iron — in cannons and other metal artifacts — to form iron sulfides. As long as the wood stays submerged, the sulfides do no harm. But once a ship is raised and exposed to air, they form wood-destroying acids.
When shipwrecks are salvaged, conservators typically treat them with a synthetic resin to replace the water in the wood’s cellular structure. “This preserves the wood’s dimensions so that it doesn’t shrink and twist and break apart when it dries out,” said Kimberly Kenyon, a conservator at a laboratory in Greenville, North Carolina, that is working to recover the Queen Anne's Revenge, an 18th-century frigate thought to be the pirate Blackbeard’s flagship.
The treatment developed by Corr and her colleagues goes a step further by extracting iron particles from the wood without damaging the ship's structure.
Kenyon, who is not involved with Corr's research, said she is keen to see more results from the new treatment, adding that the magnetic nanoparticles could also be used to help preserve the Queen Anne’s Revenge. “It has certainly garnered interest from us as an alternate solution to common methods,” she said.
"There are many collections that could benefit from this technology," said Eleanor Schofield, head of conservation at the Mary Rose Trust, a Portsmouth-based charitable trust that is collaborating on efforts to preserve the warship. "It can be applied to any marine archaeological wood," she said, even materials such as textiles and leather.