Researchers have developed a novel hydrogel that effectively preserves waterlogged wooden artefacts, such as shipwrecks, by neutralising harmful acids and preventing microbial decay.
The famous Vasa wreck, now on display in its museum in Stockholm, underwent a decades-long preservation process. The new hydrogel promises a much faster and safer method.
Traditional methods for conserving waterlogged wood involve lengthy processes like freeze-drying or replacing water with pressurised carbon dioxide, which can lead to brittleness or warping. These techniques aim to remove water that fosters acid-producing bacteria and wood-eating fungi, but they often compromise the artefact's structural integrity.
Hydrogel development and application
The innovative hydrogel combines potassium bicarbonate, an acid-neutralising agent, with silver nitrate, known for its antimicrobial properties. Researchers tested this hydrogel on 800-year-old wood from the Nanhai One shipwreck, discovered off China's southern coast. The gel successfully neutralised acids up to one centimetre deep within ten days, with variants containing lower silver concentrations dissolving after three to five days, thereby reducing potential surface damage.
The material dissolves over time, eliminating the need for physical removal and reducing the risk of damage to fragile artefacts.
Fact file
A hydrogel is a biphasic material, a mixture of porous and permeable solids and at least 10% of water or other interstitial fluid. Hydrogels have several applications, especially in the biomedical area, such as in hydrogel dressing.
