The Jesse Window at Wells Cathedral is one of the most splendid examples of 14th century stained glass in Europe.
It dates from about 1340 and, considering its age, is still remarkably intact. Fortunately, the window has survived the vicissitudes of time and British history (narrowly escaping destruction during the English Civil War) and so what we see today is basically how medieval glaziers designed and created it and how our ancestors viewed it before us.
There have been sensitive repairs over the centuries, of course, and steps were taken during World War II to protect the Window.
There had been growing concern over the past few years that the Window would deteriorate beyond repair unless urgent conservation work was carried out. Inspections showed that some of the lead was bowing and needed attention, and some of the leaded panels of glass were bulging and loose. More significantly, the medieval glass was suffering the effects of condensation and consequent mould growth. This was attacking the painted layers on the glass: the paint was peeling and the glass was suffering from corrosion, putting the whole medieval structure at risk.
A successful fundraising campaign to save the Jesse Window allowed us to seek the advice and assistance of a team of the best medieval glass experts in the country, as well as the eminent German consultant conservator, Dr. Ivo Rauch.
During the last eight months, the team have been working full time to save the fourteenth century glass of the Jesse Window. After recording the condition of each piece of glass and lead within the panels, the two lights and tracery above to the right hand side of the Window (as viewed from the choir) were removed.
Work then began on the panels themselves. First, both faces of the panels were photographed on a light box in both reflected and transmitted light. They were then cleaned under a microscope to ensure that the paint was not damaged in any way. The panels were wet cleaned with cotton wool swabs (tens of thousands of them) and a mixture of acetone and deionized water to remove surface dirt. Leaded light cement that had been smeared over the glass during previous works was cleaned back by careful use of the scalpel.
Panels where all or part of the lead matrix was judged in need of replacement were stripped, ready for full or partial re-leading. The conservators reported that a few vital areas of paint have been lost, and they have managed to find reference to paint 1mm reinforcing plates. Bronze support frames will stabilize the window panels and prevent them from bowing.
This exciting project is now complete; scaffolding was removed from the window during November 2014 and the beauty of the Jesse Window is apparent once again for all to see.