The ESRF gives conservation boost to a 500-year-old shipwreck

27-10-2021

The ESRF has allowed scientists to discover nanoparticles that could lead to degradation in a 500-year-old shipwreck: the Mary Rose, an English warship.

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Almost 40 years ago, a salvage operation brought to the surface the Mary Rose warship, which used to be Henry VIII’s favourite warship and sank in 1545. Throughout these years, scientists have been using conservation treatments to preserve it. Unfortunately, the remains of the ship are vulnerable to degradation after spending more than 400 years at the bottom of the sea, where harmful deposits collected inside the ship’s wooden hull.

A team of researchers, led by the University of Sheffield, with the University of Copenhagen, Columbia University, the ESRF and the Mary Rose Trust, has used ctPDF, an x-ray technique available at the European Synchrotron Radiation Facility (ESRF), to obtain vital information on the nanostructure of substances lodged within the ship’s wood and that could lead to the Mary Rose degrading. 

Researchers were previously unable to obtain information on the nature and structure of these deposits, as they are incredibly diverse and exist on such a small scale. The fragility of the remains also hindered efforts to find out more about the substances.

ctPDF has enabled researchers to identify the harmful deposits for the first time and in a non-destructive way. Serena Cussen, Chair in Functional Nanomaterials at the University of Sheffield and corresponding author of the publication, explains: “This project has brought together researchers from around the world to uncover the nature of potentially harmful deposits lodged within the wooden hull of the Mary Rose. These deposits, when exposed to air, can act to degrade the wood. By understanding their structure, we might understand better these degradation pathways, as well as develop treatments that target their removal”.

The team, which included researchers from the University of Sheffield, the Mary Rose Trust, the University of Copenhagen, Columbia University and the ESRF, came to beamline ID15A at the ESRF to carry out the experiments. “This is the first time that we have used the technique of X-ray total scattering with computed tomography to successfully study cultural heritage samples at the nanoscale. This work opens doors to new experiments in the domain of conservation," explains Marco Di Michiel, scientist in charge of beamline ID15A at ESRF and co-author of the study.

They discovered zinc-containing nanoparticles lodged within the ship’s wooden hull. “The zinc sulphide deposits come from anaerobic bacteria living in the wood as it sat sunk in the seabed, and our results were like a micro-scale archeological dig where, by studying the location and composition of the deposits, we could see how the bacteria colonised the wood and what they ate,” explains Simon Billinge, Professor at Columbia University.

Towards new conservation treatments?

Aside from the nanoparticles, the researchers used the x-ray method to locate the deposits of a polymer that was sprayed on the ship in 1982 to help preserve it after it was salvaged from the seabed. 

At the time, scientists believed that the polymer would lend mechanical stability to the remains, however there is now evidence that the polymer can itself degrade. If the polymer starts to breakdown, it would produce degrading acids that could damage the Mary Rose - so knowing where the polymer is within the ship’s wood and tracking it over time is crucial for the conservation of the artefact.  

The polymer can now be tracked using the ctPDF method. Eleanor Schofield, Head of Conservation and Collection Care at the Mary Rose Trust and corresponding author of the study, explains: “To be able to look inside a piece of Mary Rose wood and see not only the structure but also the level of degradation, previous conservation treatments and other inclusions from the marine environment, is a fascinating insight. It provides us with a wealth of knowledge which we can use to further understand how the materials will react to certain treatments and environments and from that, devise future conservation strategies to keep them safe for years to come.”

Reference:

Jensen, K M.Ø. et al, Matter, In press, Corrected proof, 27 October 2021.

Top image: The hull of the Mary Rose. Credits: The Mary Rose Trust.