Conserving waterlogged wooden artefacts

Supplementary content information

An EPSRC-supported research team have developed a safer, greener method for conserving waterlogged wooden artefacts, such as those recovered from Henry VIII’s ship, the Mary Rose.

  • New natural polymer material protects against the primary causes of waterlogged wood degradation
  • Formation of harmful corrosive acid is prevented by ‘trapping’ ions from iron fastenings and bolts
  • System enhances structural integrity and protects against biological damage

The team, led by Professor Oren A Scherman, from the University of Cambridge, in collaboration with the Mary Rose Trust, developed a natural polymer-based system that appears to protect against all three primary causes of degradation in waterlogged wood, the first time this has been possible in a single treatment.

Initial tests of the material, carried out on wooden artefacts recovered from Henry VIII’s warship, the Mary Rose, have shown that it effectively protects waterlogged wood against the main causes of collapse, and is a safer, greener alternative to current methods. 

A number of factors can contribute to the degradation of wooden artefacts once they are removed from the sea. Warping or cracking as the wood dries out, damage from bacteria, and the build-up of acid formed by the corrosion of iron fastenings and bolts can all cause cellulose and hemi-cellulose – significant components of the wood cell wall – to break down.

The protective material created by the team uses two naturally-sourced polymers to build a molecular cage around the iron ions, preventing them from acting as a catalyst and generating acid in the timber. This not only traps iron ions, it helps to enhance structural stability. In addition, the material has antibacterial properties which protect against biological damage. Even if there is no iron in the wood, the treatment still works. The team are now conducting tests on larger wooden artefacts.

Dr Zarah Walsh, a postdoctoral researcher on the team, says: “The polymer gets stronger relative to the amount of iron that’s there – in that way it’s quite responsive to its environment.”

Dr Walsh performed the research while a postdoctoral researcher in the Department of Chemistry’s Melville Laboratory of Polymer Synthesis, which is led by Professor Oren A Scherman, an EPSRC RISE Rising Star.

The research was funded by EPSRC, the European Research Council, the Walters-Kundert Charitable Trust, the Mary Rose Trust, the National Science Foundation (NSF) and the US Forest Service and Forest Products Laboratory.

Image credit: Geoff Hunt, PPRSMA