The sea is an unforgiving environment for any shipwreck, but sunken wooden ships are particularly susceptible to the corrosive effects of seawater and its high bacterial content. The risk of deterioration does not end when archaeological remains are recovered. Preservation methods such as freeze-drying and displacement drying can make artifacts more fragile, distort their overall shape, and take months to complete. But a new hydrogel developed by Chinese researchers could offer a safer option for eradicating harmful microorganisms and acids in the wood of flooded shipwrecks.
This innovative content is ACS Sustainable Chemistry and Engineeringis the result of collaborative research between multiple institutions in China, including Sun Yat-sen University and the Hong Kong University of Science and Technology. Experts have already used certain hydrogels in similar artifact recovery projects, but they require removing the coating after injecting the hardener into the wood, a potentially damaging procedure in itself. However, this new material safely dissolves after a few days without direct physical removal.
To create this material, the researchers combined precise amounts of acid-neutralizing potassium bicarbonate and antimicrobial, polymer-bound silver nitrate. The substance also relied on sodium alginate, a natural polysaccharide made from brown algae that is often used as a thickening agent in the food, cosmetic, and pharmaceutical industries. After mixing, the team tested the hydrogel’s capabilities in a proof of concept using real shipwreck wood. In this case, the samples were taken from an 800-year-old shipwreck provided by the Guangdong Maritime Silk Road Museum.
Reacher and colleagues then analyzed the preservation ability after applying multiple versions of the hydrogel coating to blocks of wood soaked in brine. According to Notice of December 3rdeach hydrogel mixture neutralizes acids up to 1 cm deep within 10 days after application. However, the hydrogel containing less silver nitrate began removing the harmful chemical after just one day. Similarly, lower amounts of silver nitrate gel liquefy completely after three to five days, while higher amounts of silver nitrate leave the coating a “gooey solid,” according to the study. Overall, the hydrogel-treated wood ended up being less brittle than the samples treated with the more solid gel.
[Related: A hunk of coal from the Titanic could fetch $780 at auction.]
“… [T]Incorporating a hydrogel system [silver nitrates] “We demonstrate remarkable preservation effects of wooden cultural properties in terms of solubility, elasticity, and antibacterial properties,” the researchers wrote in the paper. Research conclusionIt added that it hoped the new material would “offer a timely and versatile solution for preserving wooden cultural heritage.”
