Friday, February 08, 2008

 

'Super-scope' shines on Mary Rose

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BBC
By Rebecca Morelle
February 08, 2008


Scientists are using a "synchroton" to study the Mary Rose's timbers

The research is taking place at the Diamond synchrotron, a beam-generating machine that covers the area of five football pitches.

Scientists are using the facility in a bid to fine-tune the conservation of the historic vessel's timbers.

The Mary Rose, pride of Henry VIII's English fleet, sank in 1545 and lay on the sea bed until being raised in 1982.

The work carried out at Diamond will help conservators understand more about the sulphur compounds buried deep within the ship's timbers.

Researchers aim to find out how stable they are, as these can be converted to sulphuric acid when oxygen is present - threatening preservation efforts.

After sinking in the 16th Century, the Mary Rose lay on the bottom of the Solent for the next 400 years.

Thanks to a protective covering of sea-bed sediment, many of her timbers and artefacts remained intact when she was raised from the salty depths in 1982.

Since then, scientists have been endeavouring to ensure the preservation of the historic vessel, which is housed at Portsmouth's Historic Dockyard.

From 1994, her hull timbers have been continuously sprayed with a water-soluble wax called polyethylene glycol.

Dr Mark Jones, from the Mary Rose Trust, who is leading the research project, said: "It prevents the wood from distorting, shrinking, splitting, cracking or collapsing.

"But, in addition to that you have to remove some of the salts that have occurred over the many centuries - chlorides, which are easy to wash out, and the iron and sulphur compounds, which in the presence of oxygen can be converted into sulphuric acid."

The biochemist said that over the last 15 years, researchers had successfully neutralised all of the acids in the wood and had removed the vast majority of the troublesome compounds.

Dr Jones told the BBC News website: "What we are now trying to do using Diamond technology is to investigate any remaining compounds that could present a threat in 20, or 30, or even 500 years time."

Silver doughnut
The scientists, from the Mary Rose Trust, the National Museum of Scotland, Daresbury Laboratory and the University of Kent, have been placing thin slivers of the ship's timber into the "microfocus beamline" at the Oxfordshire-based synchrotron.

The facility - sometimes described as a super-microscope - works by speeding electrons around a huge doughnut-shaped chamber until they are travelling so fast that they begin to emit light.

These intense rays are then channelled off into beamlines and focused on to samples of material, like the Mary Rose timbers, allowing their fine structure to be analysed.

By observing the wood at the cellular level, the team has been able to look at compounds of sulphur and iron buried deep within the timbers.

Dr Jones said: "Over time, sulphur has bonded with the cell walls in the wood, producing a compound that is extremely stable and impossible to remove because it is so deep in the timber.

"With the help of Diamond and university research, we want to make sure that these compounds will remain stable over long, long periods of time under different display conditions."

He added: "Essentially, what we are trying to do is to fine-tune the conservation process so that it lasts for many, many more centuries."

Charles Barker, managing director of Mary Rose Archaeological Services, added: "It is all about looking at potential problems that might crop up that we don't know about now."


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