UK: high-tech glazing for Lincoln Cathedral medieval windows

Four medieval windows of the Lincoln Cathedral – dated from the 13th century – are to be fitted with protective glazing, which will shield the stained glass from the elements, while special monitoring sensors will ensure the new glazing is set at exactly the right position to keep the medieval glass protected.

New protective glazing could be fitted to four medieval windows in Lincoln Cathedral to protect the historic stained glass.
Special monitoring sensors will even be fitted to the windows of the cathedral, based in central England, to ensure the new glazing is set at exactly the right position to keep the medieval glass protected.
The project, which is expected to cost GBP 550,000, is planned for four of the lancet windows beneath the Bishop’s Eye, which date from the 13th century.
The new scheme, if agreed by the cathedral’s Glazing Advisory Committee, will start early next year when the old glass is removed for conservation, and new, specially made, protective glass fitted to the window’s exterior recess before the conserved windows are re-hung behind it on special brackets.
The new protective glazing will shield the stained glass from the elements, however, the airflow and condensation between the sheets must be exactly right to prevent any damage to the medieval glass. Sensors will therefore be fitted between the two windows and the measurements automatically sent to a specialist company in Cambridge where they will be monitored for a year. That will allow the works department to adjust the distance between the two windows to the exact millimetre needed. Each of the four windows needs to be measured and monitored individually because they are all slightly different sizes so the entire project will take four years to complete.
“It is a long and very detailed process but it will ensure this priceless medieval glass is protected from the elements,” said works department manager Carol Heidschuster.
“Each window needs to be accurately assessed for humidity, air flow and temperature and monitored for a year so we can ensure the windows are placed at exactly the right distance from one another.
“Most visitors view the stained glass from the inside with the light travelling through it and we specially design the outer panels to ensure the lead work patterns match those on the inside.
“So visitors will still be able to enjoy the splendour of the windows while they are being protected.”
The first window the Lincoln Glazing Department will be conserving is the one damaged by a breakout in 2008 when an intruder used it to escape. The medallion depicted Moses in a biblical scene.