Any stained glass window
that’s been exposed to the weather or has been improperly installed may
need to be restored, according to Bill Reinart, of Reinarts Stained
Glass Studios of Winona, Minnesota. The lead “came,” the metal between
the glass pieces, oxidizes, becomes brittle, cracks, buckles, and
stretches. The putty or grout, pushed under the lead giving the window
its rigidity, has usually fallen out by this time, making the window
rattle, as well as showing obvious signs of buckling and cracking of the
However, before a window can be restored, it must be inspected by a
professional such as Reinart to determine the exact cause of its
deterioration. Once that’s determined, work can proceed.
The restoration process begins by first removing the window panel from
the frame. After the restorer takes a rubbing of the design, he can then
remove the individual pieces of glass from the old lead. But before he
can work on restoring the lead, each piece of glass must be cleaned,
removing the old putty, paint and dirt that has accumulated over the
years. He’ll also have to replace any broken pieces using the same or a
similar type of glass. The window's original fabric, especially the
original glass, should be re-used whenever possible. The work should
also be thoroughly documented for future reference. And, unless imminent
loss will result, all repair and restoration methods used should be
After he putties the window, it’s ready to be re-installed. By the time
the process is finished, the collector has, in every respect, a new
window, with the historic glass intact. While it’s possible to match
color and paint, it’s often not as easy to restore a certain texture. In
this case, the restorer will have to replace the textured glass with
something similar. The finished window will be more brilliant after the
glass is cleaned and restored and shouldn’t require re-leading for about
200 years or more.
If the window is painted, it may require even more intensive
restoration. “Often windows are painted with a combination of kiln-fired
and cold (regular) paint which can come off,”
Reinart says. “Faded painting on windows often is the result of improper
firing. A correctly fired paint design should last for the life of the
window. Today, we use electric computerized kilns to fuse the paint onto
the glass. It makes a difference how long the paint is fired, how long
it stays at the optimum temperature and how it cools. If glass cools too
fast, it becomes brittle.”
Complete restoration offers the best long-term benefits, but this
approach is often not financially practical. “Total re-leading is often
not necessary,” says Reinart. “But Tiffany windows and those with layers
of glass and intricate leading are the most difficult to restore and,
therefore, the most costly.”
While in-place repairs are appropriate in certain instances, they rarely
serve as long-term solutions to the problems of a window. So, most
frequently, a compromise between complete, museum-quality restoration
and simply patching the window is the solution.
What is the Purpose
of the Restoration?
Before considering the specific needs of a window, such as which
technique to employ where, the craftsman must consider general issues of
the overall purpose and scope of the intended restoration. Is this
window a fine and valuable example of the highest level of stained glass
art? Was it created by a recognized master artist or studio? If so, it’s
essential to employ the most meticulous and demanding museum-quality
restoration techniques to preserve the work.
Is the window a remarkable example of its genre? Again, if so, it must
be approached in the most sensitive and delicate way. Unlike easel
painting, sculpture and other fine arts, many of whose best examples are
protected in museums and art galleries around the world, most of the
finest examples of stained glass art reside in churches, public
buildings and residences, where they’re exposed to more potentially
damaging elements and circumstances. Then, too, as a general rule,
stained glass windows, even museum-quality ones in their original
settings, are under considerably less preservation scrutiny than their
painting and sculptural counterparts.
The proper restoration of these windows involves extraordinarily
time-consuming, delicate, frequently costly, restoration methods. And
the restoration of a valuable window should be attempted only by the
most knowledgeable and experienced craftspeople.
Even windows which might be described as “commercial” ones—that is,
they may have originally been part of a catalogue offering, like those
sold through Sears & Roebuck, or common designs of the time—should be
looked upon as examples of the art of that period. Although complete,
museum-quality restoration of these windows may not yield the same
financial return as the more recognized artistically unique windows,
their restoration is nonetheless important.
If no documentation exists for the window in question, the collector
should gather as much information about it as possible. The window
should also be photographed on 35mm slide film. The window’s owner
should also prepare, a provenance, as with fine furniture, including the
window’s maker and history. This should be filed with the Census of
Stained Glass Windows in America, which is currently cataloging all of
the windows in the United States for scholarly purposes.
of Restoration Can a Collector Do?
Collectors should avoid cleaning their own windows if they’re painted or
adorned with other surface decoration, as modern cleaning agents might
damage the painted surface. The least intrusive cleaning method is to
dust the window with a feather duster or soft cloth. Accumulated cobwebs
and insect debris can be gently vacuumed away or dusted.
If a heavy build-up of dirt exists on unpainted windows, the collector
can perform a wet cleaning with a lukewarm solution of water and a
non-ionic detergent, such as Triton X-100 or OrvusTm. It’s important
that no residue of these cleaning products be left on the glass. If
possible, the windows should be rinsed with lots of clear water
afterwards. Cleaners containing either ammonia or alcohol should not be
used, as these chemicals may react with the lead or the cement
compounds. Stubborn accretions of oil-based paint that may have been
accidentally deposited during a window’s lifetime can be removed with
methylene chloride thickened with cellulose.
If a window is in rather good shape but has one or two pieces of broken
or cracked glass, a craftsperson can perform a stopgap repair. Though
these repairs are temporary measures taken to prevent further
deterioration and possible damage, they’re not restoration.
Before executing a stopgap repair, however, the collector should
ascertain whether numerous repairs needed within one panel will severely
weaken the window. Also, will the material of the supporting matrix
support an in-place repair? Zinc came and round lead are more difficult
to work on than flat leads, while copper-foil is virtually irreparable
in a vertical plane, due to the physical impossibility of drawing an
adequate solder bead. If the repair is appropriate, the glass should
match the texture, color and density of the original, whenever possible.
In some cases, it may be too costly to restore a window at the present
time. If a collector cannot afford a complete restoration, then
stabilization of the window is the next best step. For instance, the
edges of cracks can be damaged further if they are not stabilized. As
the glass flexes, the pieces abrade one another and result in shelling
of the glass edges.
Questionable restoration techniques can diminish the artistic value of a
window, and in some cases, actually accelerate the deterioration of the
Certain repairs cannot be done while the window is in place in a
building. Re-cementing a window must be done
while it’s lying flat on a bench. All of the old putty must be carefully
removed with hardwood picks, and after the cementing process, the panels
should remain in a supported, flat plane for a minimum of two weeks to
let the putty set up.
It’s also impossible to flatten bulges in-place without breaking the
glass. To properly flatten a panel, the support bars must be removed,
the putty must be scraped out from under the lead flange, and the window
must be gently coaxed into its original design plane.
Restoration is a term used broadly and, quite often, inappropriately. A
restoration brings a work back to its former undamaged condition and
doesn’t affect the value of the window, as is often the case with
furniture. “There’s a ton of misinformation out there on restoring
stained glass,” says Reinart. “It’s important to go to someone who knows
the right procedures.”
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