Christina Duffy, Paul Garside, Gavin Moorhead and Cordelia Rogerson, British Library

Imaging Magna Carta: Incorporating new technologies into old workflows

Magna Carta is one of the world’s most famous documents providing inspiration for some of today’s fundamental liberties. In 1976 the British Parliament loaned the iconic 1215 Magna Carta to the United Stated in honour of 200 years of American Independence. In anticipation of the loan, six manuscripts at the British Museum, later to become British Library collections, were rehoused into wooden frames. In preparation for the British Library’s exhibition to mark the 800 year anniversary of Magna Carta, the copies of this charter held by the Library, as well as several related documents, were removed from their existing frames, assessed and reframed in a more appropriate manner. While out of their frames the manuscripts underwent a series of technical analyses, including near infra-red spectroscopy, digital microscopy and multispectral imaging.

The British Library’s multispectral imaging system from MegaVision integrates high resolution photography and spectral reflectance imaging. It is a non-destructive and non-invasive technique capturing up to 42 images which reveal faded and erased information invisible to the naked eye. These include 14 wavelengths (365 nm in the ultraviolet to 1050 nm in the infra-red), 10 filter wheel shots, and 18 raking light shots.

The ‘Burnt Magna Carta’ (Cotton charter xiii 31a) was a particularly challenging case. A combination of fire-damage and subsequent 19th century restoration attempts rendered much of the ink lost. Further image processing was required. Principal Component Analysis (PCA) is a statistical procedure and iterative process which uses orthogonal transformations to order data. Six iterations produced an output where much of the text was recovered. This was applied to all images and a montage of the entire recovered charter was generated.

Multispectral images resulted in newly discovered inscriptions, marginalia, unknown conservation repairs, seal markings, fold lines and a complete visual documentation. While scientific analysis took place, conservation matt cutting and fabric wrapping went ahead. The charters were mounted into their new frames ready for display. Captured multispectral images were examined by leading scholars during the historic unification event in February 2015 when the four original 1215 Magna Carta manuscripts (two from the British Library, and one each from Lincoln and Salisbury Cathedrals) came together for the first time. The images of the recovered text enabled direct comparison of the scribal hands used on all four charters.

Five of the six the framed charters went on display at the British Library’s major exhibition Magna Carta: Law, Liberty, Legacy, while the two 1215 British Library copies were also displayed at the House of Lords. One of the images of the recovered text was also included in exhibition increasing awareness and raising the profile of our conservation department.

The combination of physical examination, microscopy, multispectral imaging and near infra-red spectroscopy resulted in a complete condition assessment. The development of multispectral imaging as a method of digital preservation and text recovery has highlighted the advantages of incorporating new technologies into old workflows and is now firmly established internally as a valuable conservation technique.