New Consolidants for the Conservation of Archeological Wood
The preservation of cultural heritage is of great importance worldwide and, as such, has been the focus of an increasing number of research projects in recent years. In spite of considerable efforts around the world, significant problems have arisen with the conservation of many shipwrecks. The most common issues facing conservators are structural instability upon drying and biological degradation stemming from the aquatic flora and fauna active around the excavation site. However, many important artefacts – such as the sixteenth century warship Mary Rose – also suffer from metal ion saturation from degraded bolts and fittings. In most cases Fe3+ is the greatest problem, which catalyses the production of sulfuric and oxalic acid in the waterlogged timbers, adding chemical degradation to the potential conservation issues. Moreover, the Fe3+ also feeds biological degradation by providing bacteria with an iron source for sustained growth. As such, multi-functional consolidants are greatly needed to tackle not only the many-pronged conservation issues already visible, but also to prevent others from evolving over time. This paper discusses the recent successes in the development of such materials from sustainable, bio-based sources and some potential areas for the future development of these tools.
KeywordsWaterlogged archaeological wood Mary rose Poly(ethylene glycol) Bio-based polymers Supramolecular materials Conservation
The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union’s 7th Framework Programme (FP7/2007-2013) under REA grant agreement n. PCOFUND-GA-2013-609102, through the PRESTIGE programme coordinated by Campus France, awarded to ZWK (PRESTIGE-2016-2-0008). ZWK acknowledges the help of Drs J.T. Hodgkinson, M. Welch, J. Sedlmair, A. Koutsioubas, and Profs. D.R. Spring, C.J. Hirschmugl, C. Toprakcioglu, A. Dent and J.R. Nitschke in the characterisation and development of these materials. ZWK and OAS acknowledge financial support from the Mary Rose Trust, the Engineering and Physical Sciences Research Council (EPSRC) UK and the European Research Council (ERC) (Starting Investigator Award No. 240619, ASPiRe). OAS also acknowledges the Walters-Kundert Charitable Trust for a Next Generation Fellowship. ERJ thanks the EPSRC for a doctoral training grant.
- 4.Almkvist, G. and I. Persson. 2008. Fenton-induced degradation of polyethylene glycol and oak holocellulose. A model experiment in comparison to changes observed in conserved waterlogged wood. Holzforschung 62, 704–708.Google Scholar
- 5.Almkvist, G. and I. Persson. 2008. Analysis of acids and degradation products related to iron and sulfur in the Swedish warship Vasa. Holzforschung, 62, 694–703.Google Scholar
- 7.Bjurhager, I., H. Halonen, E.L. Lindfors, T. Iversen, G. Almkvist, E.K. Gamstedt and L.A. Berglund. 2012. State of degradation in archaeological oak from the 17th century Vasa ship: Substantial strength loss correlates with reduction in holo(cellulose) molecular weight. Biomacromol. 13, 2521–2527CrossRefGoogle Scholar
- 9.Gray, F. M. 1997. Polymer Electrolytes. RSC Materials Monographs. Cambridge: Royal Society of Chemistry.Google Scholar
- 12.Berko, A., A.D. Smith, A M. Jones, E.J. Schofield, J.F.W. Mosselmans and A.V. Chadwick. 2009. XAS studies of the effectiveness of iron chelating treatments of Mary Rose timbers. J. Phys. Conf. Ser. 190, 012147.Google Scholar
- 18.Walsh, Z., E.R. Janeček, J.T. Hodgkinson, J. Sedlmair, A. Koutsioubas, D.R. Spring, M. Welch, C.J. Hirschmugl, C. Toprakcioglu, M. Jones, J.R. Nitschke, and O.A. Scherman. 2014. Supramolecular polymer networks as next generation consolidants for archaeological wood conservation. Proc. Nat. Acad. Sci. USA 111, 17743–17748.Google Scholar