Few items last forever, and stained glass windows can break. Some of them have individual panes that have broken over the years, but it is often the wood surrounding them that has worn down. Taking out the window can be a difficult procedure with onlookers biting their nails, but most professionals are able to do it without adding to the damage. Repairing old stained glass windows is an art, and it often takes months for them to assemble all the right parts to get the job done.
A repair job of this magnitude begins with the artisan making a full evaluation of the damage. It would do little good to only make repairs that are noticeable, and then the window could disintegrate because a small hole in the frame allows water damage months or years later. Repairing this type of art requires a person to be patient as they examine every facet of the window, and they must then decide how to proceed.
There are times when it is actually easier to take the entire window apart, and then each individual piece can be re-seated in new caning. Older windows used lead, but other alloys are used today for safety reasons. The window would not look right if different metals were used, and that is often the reason the entire window is reset.
The framing on most older stained glass windows is made of wood, and weathering is generally the issue that causes the damage in the first place. While the actual window may have only sagged to one side, re-caning or replacing some of the original glass pieces might be a good idea while the frame is being rebuilt. Doing a thorough repair job often allows the piece to be placed back in its original spot and remain there for decades into the future.