A
stained glass window consists of many individual
pieces of glass held together by strips of lead
caming. The average life of the window is usually 70
to 100 years. As the lead and putty decay, the
entire structure of the window begins to weaken
under its own weight. Expansion and contraction of
the lead due to heat from poorly ventilated exterior
protective coverings also contribute to the windows
movement. The sagging and bowing are evidence of the
final stages of this process.
If this problem is not addressed, the glass will
crack or fall out of the caming until the window
eventually collapses. However,
proper
restoration can extend the life of the stained
glass window for up to another 100 years.
