Science Ahoy!

Preserving the Mary Rose with Diamond light

Image Preserving the Mary Rose with Diamond light

Geoff Hunt painting of the Mary Rose sinking. Geoff Hunt, PPRSMA

 

What is the connection between Henry VIII’s sunken flagship and one of world’s most advanced scientific machines? The Mary Rose sank off the coast of England in 1545, and was raised from the seabed more than 400 years later in 1982. From that moment, the race was on to preserve the fragile warship from acid decay.
 
No one knows for sure exactly how the Mary Rose went down. The most likely explanation is human error; the ship turned too sharply and flooded, killing almost all of the 400 men on board; all the while, a powerless Henry VIII stood by on the cliffs watching as his prized ship sank. After this tragic event, the vast hull lay at the bottom of the ocean for four centuries, half covered by silts on the sea bed. It’s these silts that we have to thank for the miraculous state of the Mary Rose today – the tight sediment layer helped to prevent microorganisms from eating away at the ship’s wooden frame. And so the Mary Rose is beautifully preserved, but there’s a lot more to do to make sure she stays that way.
 
After so many years spent buried beneath the sea, there’s only one way to dry out the Mary Rose: air. Unfortunately, the oxygen in air also happens to pose the greatest threat to the ship’s wooden frame. The timber hull of the Mary Rose contains traces of sulphur, absorbed from the surrounding underwater environment. This sulphur wasn’t a big deal whilst the ship was underwater, but now it’s been brought up and exposed to oxygen, and when oxygen reacts with sulphur, it creates acid – not good news for 500 year old wood.
 
Geoff Hunt, a view of the Mary Rose hull
Geoff Hunt, a view of the Mary Rose hull
Sulphur is particularly problematic in parts of the ship that were close to iron elements, like screws, bolts, nails and cannons. Iron acts as a catalyst for sulphur oxygenation, making these areas especially at risk. If this process was left to go ahead, the Mary Rose would quickly begin to disintegrate.
 
Back in the eighties, there wasn’t much that could be done to prevent oxygenation, so the ship was kept constantly wet. In the meantime, conservation scientists set about looking for a more permanent solution. In 1994, polyethylene glycol or PEG was introduced into the sprays keeping the ship wet. This mixture was absorbed into the ship, where it replaced water molecules with polymers that reinforce the wood, preventing decay.
 
In 2013, when the correct level of PEG was reached, the decision was made to turn off the pumps and to start drying out the Mary Rose. This ongoing process is critical to the ship’s preservation. If the PEG has been successful, then we should see the Tudor flagship retain its glory; however, if there are still elements of sulphur present in the hull, then signs of deterioration may soon start to show.
 
That’s where Diamond comes in. Research on the Mary Rose has taken place at other synchrotrons, but Diamond first became involved in 2008, when the X-ray beam was used to determine how sulphur and iron compounds were distributed and how they interacted inside the individual cells of the wood. Now that the ship has started to dry out, scientists can use Diamond to analyse the impact of oxygen on the ship and work out whether the conservation efforts have been truly successful. 
 
Eleanor Schofield is Conservation Manager at the Mary Rose Trust. It’s her job to find ways of monitoring the ship as it dries, and Diamond’s B18 is a powerful tool for helping her to keep a close eye on things. One of Diamond’s spectroscopy beamlines, B18 supports a technique called X-ray absorption spectroscopy (XAS). Different elements fluoresce when exposed to X-ray light, so by exposing slivers of timbers from the Mary Rose to the beam, Eleanor can determine exactly what elements are present and their form. This helps her to monitor levels of sulphur in the drying wood, and to spot any potential oxidation and resulting acid build up as the ship dries.
 
“Time at Diamond is crucial to monitoring the progress of the ship”, Eleanor observes. “People often ask me what science has to do with the Mary Rose; the answer is ‘everything’! Facilities like Diamond allow us to find ways of conserving ancient artefacts – we need the detail Diamond offers because this process often starts at the cellular and molecular level. Science is a vital part of conservation, and it’s great to know that we’re playing our part in preserving our cultural heritage.”
 
Relics like the Mary Rose help us to understand and connect with history. And yet, sometimes it is only with cutting-edge machines like Diamond that we can keep that cultural heritage alive. Eleanor and the Mary Rose Trust have been hugely successful in preserving this important slice of history, and their ongoing work demonstrates that whilst Diamond undoubtedly brings the future closer, it also allows us to protect our past.
 
 
To see the ship up close, why not visit the Mary Rose museum? Details here: www.maryrose.org
 
 

Read more about cutting edge research in Diamond's magazine: