Preserving ancient artifacts for the next millennia

Abstract

When wood is kept dry, it can remain intact for millennia, as evidenced by numerous artifacts from ancient Egypt (1). However, when wood interacts with water, numerous problems arise that can cause the wood to become permanently damaged or destroyed completely. Wood exhibits swelling on moisture uptake and shrinkage on drying, and these cyclical moisture changes lead to internal stresses and can eventually form splits and checks within the wood. When there is an abundance of moisture in the wood, it is susceptible to microbial growth, fungal decay, corrosion of embedded metals, and chemical depolymerization from certain ions and free radicals. These moisture-induced damage mechanisms pose problems for conservation of wooden artifacts that were at one time waterlogged, notably recovered warships such as the Mary Rose. In PNAS, Walsh et al. (2) propose a way to protect historical artifacts from moisture-induced damage mechanisms by introducing chemicals that polymerize within the wood structure. The interpenetrating polymer network strengthens the artifact, while at the same time, functional groups on the polymers protect the wood from further breakdown by biodeterioration and chemically induced depolymerization.

Citation

Zelinka, Samuel L. 2014. Preserving ancient artifacts for the next millennia. PNAS. 111(50): 17700-17701. https://doi.org/10.1073/pnas.1420835111