Conservation United Kingdom

Software could reconstruct medieval mosaics

Project to conserve Coventry’s 5,000 stained-glass fragments—some believed to be the work of a master

The pieces were stored next to the cathedral’s boiler

Experimental software developed to reassemble Cold War documents may soon shed light on the mysteries surrounding around 5,000 medieval stained-glass fragments from Coventry Cathedral, as well as on the work of John Thornton, one of England’s greatest stained-glass artists. The British arm of the World Monuments Fund is funding a project to prevent the glass from deteriorating.

The glass was removed from the cathedral before German air raids left the building a shattered ruin during the Second World War. The majority of the pieces have remained disassembled ever since, and have been stored in poor conditions next to the building’s boiler.

The chief executive of the World Monuments Fund, Jonathan Foyle, says that, to a medievalist, “it is like rediscovering [a painting from] Picasso’s blue period in fragments in a basement. It is a magnificent puzzle.”

The full history of the glass is not clear, but the fragments were mosaics, rather than complete windows, installed in the clerestory in the 19th century following earlier reorderings of the church.

Although some choice panels have been extracted, many of the fragments remain unexamined, having been catalogued eccentrically by colour and image. The categories include portraits of merchants and their wives, beasts and angels, architectural visions and calligraphy. Foyle describes them as a “medieval encyclopaedia”.

Stylistically, some fragments appear to be the work of John Thornton. The first references to the artist appear in a 1405 contract for York Minster’s Great East Window—one of the masterpieces of medieval art. The contract stipulated that the cartoons and important elements be done by his own hand. His characteristic approach consists of white glass of sinuous yellow silver oxide stain with deeper reds and blues used in backgrounds.

“Thornton brought an entirely fresh design eye and gave manuscript scenes fresh vigour on a huge scale,” says Sarah Brown, the director of the York Glaziers Trust. “He has yet to be explored. It will be difficult to say if any particular piece is by his hand, but we will be much more confident in talking about his hand.”

Ian Crick-Smith, a researcher at the University of Lincoln, says that renderings of the broken edges of the glass will be created using two- or three-dimensional laser scanning, and that software will then be used to suggest best matches and alignment. “There is definitely a growth area for digital technology in the heritage investigation sector,” he says. Similar technology was used by Princeton University to help reconstruct fragments from ancient frescoes at Akrotiri.

The software was developed after the fall of the Iron Curtain, when it was used to recreate documents that had been destroyed by shredding and tearing. “It has also been used to reassemble damaged works of art on paper,” Crick-Smith says. “We don’t know of any other instance where this has been used for stained glass.” The composition of the glass and Thornton’s production system are also being explored.

The conservation is part of a larger project to investigate the cathedral’s ruins. The public will be invited to witness the glass conservation process later in the year, and pieced-together elements will be incorporated into contemporary works of art for the cathedral.

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7 Jul 12
21:31 CET


Fundamentally, this is FABULOUS.

6 Jul 12
23:29 CET


There was also 15th c glass in St Mary's Hall at Coventry.

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