A new gel could hold the key to preserving thousands of wooden shipwrecks found on the ocean floor. The breakthrough, made by Chinese scientists at the Sun-Yat Sen University and the Hong Kong University of Science, involves coating waterlogged artefacts with a new hydrogel that dissolves over time. Thus, the need to freeze-dry decaying timber, replace sea water with carbon dioxide, or, more recently, coat artefacts with potentially harmful gels that involve ‘peeling off’ precious items from the damaged artefacts is eliminated.
Published in the ACS Sustainable Chemistry & Engineering, Alignate-Nanosilver Hydrogels—A Self-Dissolving System for Comprehensive Preservation of Waterlogged Wooden Artifacts, Xiaohang Sun and Qiang Chen led a team of scientists in developing the hydrogel—combining potassium bicarbonate with silver nitrate and sodium alginate – derived from brown seaweed, used as a thickening agent for food, cosmetics and the pharmaceutical industry — before testing it on Nanhai One, an 800-year-old wreck salvaged from the South China Sea.
Sun and Chen found that wood treated with the gel retained its cellular structure and was far less brittle than samples tested with traditional gels – revealing that the “gooey” dissolving agent was ideal for preserving cultural relics: “The hydrogel system incorporates silver nitrates demonstrates notable preservation effects on wooden relics, regarding solubility, stretchability and antibacterial properties,” they said, now hoping the new solution “will provide a timely and multipurpose solution for preserving wooden cultural heritage.”
Why waterlogged timber is a treasure for archaeology
In May, Wood Central revealed that submerged wooden structures are considered green gold for archaeologists, with rare” and “well preserved” objectives dating back to the Bronze Age and even the Stone Age. Whilst in October, archeologists made an incredible find after discovering cargo and weapons that pirates used as part of a ‘dive’ around a 500-year-old shipwreck off Stockholm’s coast.
Long mystified, the wreck was discovered in 1969 after local divers discovered “a sizeable medieval trading ship filled with bricks.” However, it wasn’t until May 2022 that an archeology team conducted a full underwater investigation of the ship.Â
During the ‘deep dive,’ researchers took photos of different aspects of the wreckage before publishing the findings in the International Journal of Nautical Archaeology. Because so little is known about ships from the 15th century, anything scientists find is precious:Â Â
“Not so much is known about the architecture of these ships, so every new wreck that is surveyed increases our knowledge a lot,” said the study’s co-author Niklas Eriksson, who made a statement to US media. Samples were taken from the 15-metre-long oak hull, which lies under 26 metres of water, where they were subjected to dendrochronological analysis, a technique that archeologists have used to date the 15th-century Newport and 18th-century Endeavour.
- To learn more about wood protection, visit Wood Central’s dedicated preservation website.
