In a completely innovative approach to the problem, the technique 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.There's a video too. This technique may, for example, give us better access to some Old Testament pseudepigrapha, many of which survive only in medieval manuscripts. Some technological projects with similar goals are noted here, here, here, and links.
Using a method called microtomography, a 3-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.
Advanced 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. An image of the document as it would appear unrolled or unfolded can then be produced.
The key difference between the new method and other techniques previously developed to read un-openable historical documents is the unprecedentedly high contrast resolution it provides to distinguish between ink and parchment. This means the ink shows up very well against the parchment and is genuinely readable.
Bit by bit, a letter at a time, whatever it takes. Until we're done.