Restoration, Conservation and Preservation are intrinsically linked and it is not often the 3 are employed separately.
Faced with a broken piece of stained glass can involve several methods of treatment:
- To retain as much of the original glass as possible (conservation)
- To replace any missing fragments that are either too many or too small to make viable repairs (restoration)
- To protect all the collected fragments once a cohesive piece has been made from them (preservation)
A set of 5 stunning windows made by Mayer & Co. of London and Munich in the 1860’s had suffered some damage, but mostly a thick coating of soot from a fire in a nearby wooden screen. The windows depict the relevant greats of the age such as Tyndale and William Shakespeare; the main window depicting Caxton presenting his new printing press to the King.
This edge-bonded piece was back-plated with 1mm float glass and sealed round the edges with acid-free silicone before reinstatement into the window.
Although on a small scale, these fragment replacements are imperative to the ‘legibility’ of the window’s design. Modern resins and methods have enabled the eradication of myriad straps of lead to hold together small fragments of glass. New inserts (as seen above) can be carefully cut and painted to fill the missing gaps which, from the distance most windows are viewed, are lost to the eye amongst all the detail of the design as a whole.
Unfortunately, not all restoration is good restoration. As we can see from this image of the 2 heads of the King and Queen, the Queen’s head has been replaced with a new piece of glass painted by an inferior hand, which sits uncomfortably next to the superb work of the Mayer & Co painter’s handiwork. This is why it is important not to accept the cheapest price for such work – do so at your peril!
The rare pieces of ancient and mediæval glass found in our churches are now in such poor condition that they need protecting from the elements if they are to survive. The pitting and white spotting usually seen on the outside surface are caused by chemicals leaching out of the glass in exchange with chemicals from the atmosphere mixed with water. To prevent this, the glass has to be protected from the rain on the outside and from condensation forming on the inside.
To achieve this, the glass has to be removed, protective glazing fitted in its place and the delicate glass reinstated forward by an inch or so and ventilated to the inside of the building. For entire windows, the ancient glass can be fitted into metal frames and fixed to the inside of the mullions, leaving the protective glazing (glass, polycarbonate, laminated or toughened glass or simple leaded lights) to bear the brunt of the weather. This can also be carried out for the benefit of individual pieces of glass (as shwon above) which can be fixed proud of their supporting glazing, leaving an air gap between it and its protective glazing.