X-ray technique should help historians uncover lost information

Fragile, rolled-up historical documents could be read for the first time in centuries, thanks to new X-ray techniques.

Old parchment is liable to crack and crumble if it is unrolled or unfolded. This can create a conflict between those who want to preserve documents and those who want to read them but researchers at Cardiff University and Queen Mary, University of London believe that their approach could get around the problem. Their technique enables parchment to be unrolled or unfolded ‘virtually’ so that historians can access previously unusable written sources and gain new insight into the past. 

The technique, which the team says has been tested successfully on a medieval legal scroll provided by the Norfolk Record Office, works by scanning parchment with X-rays in order to detect the presence of iron contained in ‘iron gall ink’ – the most commonly used ink in Europe between the 12th and 19th centuries.

The approach is based on microtomography, where a three-dimensional ‘map’ showing the ink’s exact location is built up by creating images made from a series of X-ray ‘slices’ taken through the parchment. Software specially developed by the Cardiff project team combines the data obtained with information about the way the parchment is rolled or folded up and calculates exactly where the ink sits on the parchment. This means that an image of the document as it would appear unrolled or unfolded can be produced. 

Scanning takes place at the Institute of Dentistry at Queen Mary, University of London led by  Graham Davis. He explained: 'Because no commercial or research X-ray tomography scanners were capable of providing the quality of image we needed, we’ve developed our own advanced scanner which is also being adapted for a diverse range of other scientific uses, including those within our own Institute of Dentistry where enhanced, high contrast images are enabling the detection and analysis of features in teeth that we haven’t been able to see before.'

Tim Wess of Cardiff University commented: 'This is a milestone in historical information recovery. The conservation community is rightly very protective of old documents and isn’t prepared to risk damaging them by opening them. Our breakthrough means they won’t have to.'

The four year project ‘High Definition X-ray Microtomography and Advanced Visualisation Techniques for Information Recovery from Unopenable Historical Documents’ is receiving just under £1.3 million in funding from the UK's EPSRC.