Steps Involved in Stained Glass Restoration
Periodically in the life of a panel of stained glass, attention is needed to guarantee continued use of the windows. Like windows in our homes and other structures, panes of glass can be replaced when damaged. Unlike typical windows however, exact replacements cannot easily be made due to the discontinuation of production of various types and colors of glass. But as with most windows, with regular maintenance and periodic restorations, stained glass windows can last for hundreds of years.
Restoration of stained glass windows is generally needed between 80 and 100 years after the original installation. Rarely does a panel last longer than 100 years. If preventative maintenance is not performed the windows are likely to sustain irrepairable damage. The most common example of unrepairable damage is the discontuation of adequate replacement glass. In extreme cases, it may not be possible to replicate the window panel.
Windows can be partially restored without removing them from the building in which they reside. This is done by pressing cement into the channel between the segments of glass and the caming. (Note: Caming are the lines in a stained glass window and the material that holds the pieces of glass together.). This is not advisable due to the affects of nature which have a tendency to counteract any good done by recementing. If done, re-cementing an in-place window acts only as a temporary solution which delays a complete restoration of the window.
A complete restoration involves removing framed sets of windows from the structure in which they were installed. Once in a stained glass studio, window panels are removed from the frame. The windows are then completely disassembled and cleaned. At this time any repairs needed such as replacement of broken glass are made. At times the original type of glass is no longer available. Should this be the case, attempts are made to find replacement glass which will retain the integrity of the windows composition.
Disassembly involves several steps. After window panels are removed from the frames, rubbings of the various window scenes are taken. Rubbings are similar to photo copies of the window which are taken by laying a sheet of paper over the panel. Then, by rubbing charcoal or crayon over the old caming, the various shapes of glass are identified, as well as the shape of the caming. This is used as a reference that documents the original glass.
The next step is to identify the various sizes of came used in the original construction of the window. Samples of the various sizes of came are taken and taped to its corresponding location on the rubbing. This is another step taken to accurately record how the window was originally constructed and to remain historically true to the original intent of its makers. This will also help ensure that the window panels fit back into the window frame. After the old caming has been removed and each piece of glass has been scraped clean of old cement, the panels are reconstructed in flat storage boxes to keep each window separate. It is at this time that broken pieces of glass are taped together.
During reconstruction, broken glass is replaced with glass that resembles the original. If replacement is not possible, the broken pieces can be reused without threatening the structural integrity of the window. Narrow depth caming can be used between the broken pieces of glass, essentially treating the broken glass as two separate pieces. This allows repairs to be made without severely interrupting the integrity of the window as a whole.
Prior to recaming a window, a tracing is made of the space in the frame from where the panel was removed. Small dimensional variations can make a difference between a window panel fitting or not. While the windows are disassembled and reassembled, repairs are made to the window frames. When frames are beyond repair, new frames can be made to fit the original structure. New frames though, often cost more than the restoration of the windows. So, whenever possible, old frames are repaired by using a combination of wood filler, steel rods, and epoxy which can make the windows stronger than they were in their original condition. If it is neccesary to replace a frame, mahogany is generally the wood of choice, because it stands up to the harsh seasonal weather variation much better than native American hardwoods. Aluminum is also another commonly used material for reframing a window.