High-Energy X-Rays Used to Unroll Fragile Ancient Scrolls

At the recently held 2007 Festival of Science sponsored by the British Association for the Advancement of Science, Tim Wess and his colleagues at the UK’s University of Cardiff Institute of Vision announced that they have developed a method for reading historical documents that cannot be handled easily. Especially useful for determining the contents of scrolls that are too brittle to be unrolled by hand, the technique uses a high-power x-ray source to scan a document.

Software can flatten each layer of text that the x-ray technique reveals. Courtesy of Cardiff University.

For several centuries, scribes used parchment and ink composed of a mixture of iron particles and oak apples — leaves or other parts of an oak tree that have been transformed by insect infestation into apple-shaped galls. Unfortunately, the animal-based parchment contains collagen, and, over the years, the iron gall ink has degraded it, making it very brittle when dry and jellylike when damp.

The iron, along with a small amount of copper also in the ink, acts as a contrast agent — that is, x-rays passing through a scroll scatter at different frequencies through the ink and the collagen, producing an absorption image similar to those produced by lower-power x-rays used to image human bones. An x-ray tomography method developed by the group in conjunction with Graham R. Davis of Queen Mary, University of London, will be used to read fragile documents such as the Dead Sea Scrolls and several centuries-old music manuscripts.

In addition, to develop a noninvasive method for studying such documents, the researchers used the recently opened I22 beamline at the Diamond Light Source synchrotron facility in Oxfordshire, UK, to subject a sample parchment scroll to high-energy x-rays to assess the level of damage in parchment samples, including fragments of the Dead Sea Scrolls. The beamline, opened in July, produces x-rays at 3.7 to 20 keV and sends them to samples placed about 48 m away.

X-ray tomography and custom software are enabling researchers to “unroll” ancient parchment scrolls that are too brittle to handle. Courtesy of Graham R. Davis, Queen Mary, University of London, and Tim Wess, Cardiff University.

Wess and his colleagues hope to use the synchrotron to further spectroscopically analyze the collagen itself to help conservators determine the best way to preserve ancient paper and parchment documents.