| As our
stained glass treasures past through time impacts from environmental
conditions, improper cleaning and daily activities can have adverse
effects. If caught in early stages steps can be taken at a relatively
minimal cost to correct or alleviate the issue(s). When left unchecked
these effects can be devastating to the artwork. Please use this
only for a reference to quickly check the status of your windows.
If any of these factors are evident please contact a professional
to properly evaluate your art.
Signs of deterioration,
fatigue, stress and/or failure can include:
Buckling
- When the "window" appears to bulge in or out of its
original plane caused by factors like expansion, settling and freezing.
Some movement is normal and may not continue. Any signs should be
monitored for continuing movement can lead to major problems. Also
known as bulging.
Window with serious "bulge"
Paint Deterioration
- Painted Glass can be very susceptible to damage and decay caused
by poor craftsmanship/techniques and moisture. There are two major
forms of painted glass Vitreous paint - fired using a kiln to bond
paints with glass and Cold paint - oils and enamels that are not
fired. Vitreous paints when used correctly and without erosion stand
the test of time. Cold Paints tend to be a much less permanent application
and most often should be replaces with a fired technique.

Dedication on the left shows much less deterioration
than on the right.
Oxidation
- Leads and sometimes glass, especially painted, will corrode under
certain circumstances. This corrosion is caused by chemical reactions
on the surfaces from environmental conditions. Moisture and deposits
- acid rain, pigeon droppings, incense/oil smoke - all lead to various
forms of oxidation.

Signs of heavy oxidation.
Broken Glass
- Cracks or holes in individual pieces. Some cracks just add character
and can be left as the are. Holes or missing glass usually require
some form of repair.
Viewable Daylight
- There should not be any light showing between the window and its
sash or the lead and glass.

Lead deteriorated
to the point Daylight is visible
These
factors can lead to the above issues:
Thermal Expansion
- Stained glass like all materials expand and contract when heated
and cooled respectively. This is normal and should be accounted
for in original design and installation. Lead's coefficient of expansion
is twice that of steel and 3 times that of glass. Windows become
solar collectors and heat up during the day and cool at night. When
the glazing (putty) between the lead and glass becomes dry and looses
its elasticity the movement caused by expansion leads to crumbling
of the putty which inhibits the window from contracting to its original
position causing buckling and/or cracking.
Vandalism or
accidental impact - usually broken pieces from stone or
bb impacts are minimal but we have see major breakage from much
larger objects
Poor Maintenance
- Improper cleaning and/or poor past repair attempt can adversely
affect a window. Make sure that the studio you choose to conduct
maintenance or repairs has the knowledge and experience to properly
care for your glass objects. Never use windex, harsh chemical or
abrasive cleaners to wash your stained glass. Usually a soft, clean
natural hair brush will clean loose dirt and polish leads. For areas
of grime a soft cloth and warm water will get the job done.
Weatherproofing
- Use of silicones or other sealers on windows to stop
"leaks" has been a common "quick fix" - THIS
IS NEVER APPROPRIATE! Sealers deteriorate and yellow over time and
also dull the glass. It can also be very expensive to remove them
from glass properly. If a window is leaking it is a sign that the
window should be restored. Most commonly it is the sash or window
frame that is leaking.
External Glazing
(Storms) - Often plastic or glass and sometimes screen have been
used to protect a window. When done correctly external glazing works
well. If installed incorrectly the effect on a window can be devastating.
If not vented glazing can increase thermal expansion exponentially |