This Goop Is Saving Shipwrecks, Including One That’s 800-Years-Old
Shipwrecks are always in danger of erosion since the ocean’s environment is so harsh, but sunken wooden vessels are especially susceptible.
The corrosive properties and the high levels of bacteria in saltwater accelerate the decay of wood, making preservation a challenge.
Even when archaeological remains are recovered, they are still at risk of deterioration. Preservation methods like freeze-drying or replacement-drying can cause artifacts to become more brittle. They weaken and warp their shape and structure and take months to complete.
“Upon recovery and exposure to air, waterlogged wood undergoes substantial drying shrinkage and deformation. As a result, marine waterlogged archaeological wood preserved in museums becomes more sensitive to changes in humidity,” said some researchers from Beijing and Quanzhou.
But now, a new hydrogel invented in China may offer better protection for wooden shipwrecks by safely getting rid of harmful microbes and acids.
The new material was developed by researchers from several institutions, including Sun-Yat Sen University and the Hong Kong University of Science and Technology.
Other hydrogels are already used in similar recovery projects, but their coatings need to be peeled away after infusing the wood with curing compounds, potentially damaging the artifact.
The novel substance, on the other hand, simply dissolves after a few days without being physically removed.
The hydrogel is made of water and synthetic substances known as polymers. The research team combined acid-neutralizing potassium bicarbonate with antimicrobial silver nitrates that bind to polymers.
Sign up for Chip Chick’s newsletter and get stories like this delivered to your inbox.
There was also sodium alginate, a naturally occurring polysaccharide that is made from brown seaweed. It is typically used in the food, cosmetic, and pharmaceutical industries as a thickening agent. Once everything was mixed together, the team tested the hydrogel on actual shipwreck wood.
The wood samples came from an 800-year-old sunken vessel from the Maritime Silk Road Museum of Guangdong. It is believed the vessel was built during the Southern Song Dynasty, between 1127 and 1279.
The ship was discovered at a depth of over 80 feet off China’s south coast in 1987. According to the United Nations Educational, Scientific, and Cultural Organization, it was recovered and preserved in an aquarium at the museum.
The researchers also examined the hydrogel’s preservation abilities after applying multiple versions of the gel coating to the wood pieces.
Each hydrogel mixture neutralized acids generated by bacteria metabolism up to one centimeter deep within just 10 days of application.
However, hydrogels containing less silver nitrate started removing harmful chemicals after only a day. After three to five days, hydrogels with less silver nitrate were fully liquified.
Overall, wood that was treated with hydrogels ended up being less brittle than samples that were treated with more solid gels.
The researchers think that the new hydrogel can improve the preservation of wooden artifacts. There are currently an estimated three million shipwrecks on the ocean floor, per the Smithsonian Museum of Natural History.
The study was published in ACS Sustainable Chemistry & Engineering.
More About:News