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October 2013 Item of the Month

Pigments of Northumbrian Manuscripts Project

At the end of this month Celebrate Science will once again set up its tent on Palace Green to provide three fun-packed and fascinating days of free children’s events, activities, workshops and experiments celebrating science and showcasing the innovative work of the university’s science faculty. At one of the stands children will be able to explore the science of pigment analysis, as demonstrated in an exciting collaborative and multidisciplinary spectroscopy project under way deep in the ‘dungeon’ at Palace Green Library.

Image of DCL A.II.16, a Gospel written ca. 780 AD. The letter under the lens is illuminated by a 633 nm laser. The spectrum of the scattered light is analysed, revealing that the deep yellow pigment used here is yellow orpiment, or Arsenic trisulphide (As

DCL A.II.16, a Gospel written ca. 780 AD. The letter under the lens is illuminated by a 633 nm laser. The spectrum of the scattered light is analysed, revealing that the deep yellow pigment used here is yellow orpiment, or Arsenic trisulphide (As2S3). DCL A.II.16 is reproduced by kind permission of the Chapter of Durham Cathedral.

Thanks to a generous donation by Rob and Felicity Shepherd, earlier this year a spectrometer was set up at Palace Green by a team led by Professor Andrew Beeby of the Chemistry Department, and with the burgeoning success of the project, a diffuse reflectance spectrometer and a spectral imaging camera have been added to the investigative toolbox as well.

Raman spectroscopy is a non-invasive method of measuring the spectra of light scattered, in this case, by different pigments used in the illumination of a series of 7th to 12th-century manuscripts in the university and cathedral’s collections. A laser targets a small area of an illumination or text with a single wavelength – or pure colour – of light, and fractional changes measured in the reflected light, the Raman spectrum, may be used as an index or fingerprint of the materials on the page. The science of spectroscopy is perhaps more widely known in the field of astronomy where it is used to determine the chemical composition, temperature, and other properties of distant stars and planets. Here on the microscopic scale, by identifying the spectral signature of different pigments the colour techniques and the chemical universe of early medieval scribes can be discovered, affording fresh insights into the distant minds and visions of these devotional manuscripts’ creators.

By analysing a series of samples from the Northumbrian region over several centuries, changes in northern illuminators’ practice and materials can be observed and correlated to landmark events in the region’s history – the migration of the Community of St Cuthbert from Lindisfarne to Durham, and the Norman Conquest – and to fluctuations in their access to networks of ideas and commodities from across Europe and the East. This data can in turn be compared to similar spectroscopic studies recently made of the Irish / Ionian Book of Kells, the Lindisfarne Gospels, and continental manuscripts, which will inform us about the interrelationships of these manuscript production centres and perhaps, in time, answer persisting questions on the provenance of some early texts.

Professor Beeby reports,

“The work has quickly thrown up many surprises. Our first measurements were on the Durham Gospels (A.II.17), a book believed to have been written at Lindisfarne a decade or so before the Lindisfarne Gospels was started. In this we have found widespread use of red lead and orpiment, along with a green pigment derived from copper, and an as yet unidentified purple dye. The last appears throughout the Durham Gospel and could be either Tyrian Purple (a dye derived from sea-shells) or orcein (a dye obtained from lichen). The study reveals some subtle differences between the Durham and Lindisfarne Gospels, providing hints as to how the technology of the time was developing.”
Shedding Light on the Durham Collection of Medieval Manuscripts (see below)

The work of the spectroscopy team came at a perfect time to feed in to the Lindisfarne Gospels exhibition, and their preliminary findings were presented as part of a very popular series of cases on the 'Making of the Manuscript': this free part of the exhibition upstairs in the Wolfson Gallery will re-open to the public every day from 26th October. The Lindisfarne Gospels exhibition itself has now closed its doors to the last of more than 100,000 visitors, but it is heartening to know that, in a joint enterprise with the Chemistry Department and an international team of medieval manuscript scholars, the work to understand and more fully appreciate these illuminated manuscripts and the culture that produced them goes on at the library.

Every month we showcase here an item from our Heritage Collections.