Over the last ten years our approach to a project is often as conservator rather than restorer. Gone are the days when we would automatically remove a window, dismantle it, clean the glass and relead it. Today the emphasis is much more biased towards minimal intervention. This might even involve leaving the glass in situ and carrying out preventative measures such as re-waterproofing and re-mortaring to prolong the life of the window panels. But when a windows' lead matrix becomes too brittle to hold itself together and the saddle bar support structure can no longer do its job then it’s time for it to be removed and returned to the studio.
Condition Survey of Windows
We would advise that a window report is obtained from a competent glazier in order to ascertain the condition of the glazing and its support structure. Whilst preparing the condition report for St. Alban’s Church in Copenhagen we noted that United Kingdom Royal Coat of Arms that form the cinquefoil to this window was incorrectly formed and were able to conserve and restore this. Prior to any work we will digitally photograph all of the window panels and note any relevant details.
Professional Glass Cleaning
We study the type of dirt we are dealing with, often under magnification, and the best way to deal with it without any risk to the glass surface and painted pigments. This might involve anything from swabbing with purified water, to soft brush cleaning, or glass fibre pen cleaning. Using glass fibre pens is an abrasive method of cleaning and should only be carried out by a competent conservator, it can however yield great results.
Replacement of Missing or Broken Window Panes
Missing or broken panes can be dealt with by either edge-bonding the pieces with conservation grade adhesive, or if necessary replacing them with matching glass. Much of the machine made glass produced today is often too bright and garish to use for a successful match, so we try to use salvaged glass or restoration glass where permissible. We try to re-use as much of the original glass as possible and in some cases we would attempt to insert a matching piece and edge-bond it together in order to retain as many of the original fragments.
Stained Glass Leading
Todays’ lead cames are stronger and thicker than those used before the twentieth century. During the recent project at Ely Cathedral, we noted that the old lead cames had an unusually thin core. We contacted a lead came supplier about this and had a thin core lead specially milled which overcame this problem. Although we buy in the regular sizes of lead came, we can still mill the more unusual sizes and profiles ourselves, using either a motor driven mill or a hand driven mill. Once the panels are leaded, the joints where the leads meet, are soldered and they are now ready for waterproofing.
Waterproofing Stained Glass Windows
The waterproofing compound is a mixture of linseed oil and calcium carbonate with a very small amount of red lead and white spirit. Although the application of the lead light cement is a messy and laborious process, it is also one of the most important. It would only take one small leak to undo all the good work done so far, not to mention the reputation of the studio involved.
Metalwork and Protection
The leaded panels are secured to bronze saddle bars, which in turn are secured to the window with copper ties. The glazing groove is filled with a lime-based mortar and given a final brush down. Some bigger projects will then have a post-conservation report detailing the work done and accompanied by photos of the work at different stages.
New Stained Glass Replacement
In some cases a church may be granted permission to replace the glass in an existing window with new glass. This is often desirable where the glass is of a heavy texture, an odd colour or a combination of both. A good example of this is the east chancel window at St. James Church in Southrepps, Norfolk.
Repair of Vandalised Stained Glass
Sadly, not all of our work is conservation or restoration. More often than we would like, we find ourselves dealing with the results of vandalism. Sometimes it may only be a few single pane repairs that can be dealt with insitu, or it could be much more serious. Where possible we re-use as much of the original glass as possible by edge-bonding and only replace pieces that are totally smashed or missing.
To discuss conservation of stained glass in any space in the UK or further afield please contact our studio on 01379 677111
One of our recent contracts was at St. Alban's Church, Copenhagen. See more...
We were appointed conservators for the North and South transcept window glazing at Ely Catherdral. See more...
We replaced the old cold looking pale blue colour glass in the east chancel window at St. James church. See more...