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How to Inspect Your Stained Glass

Each week, congregants thoughtfully gaze at the stained glass in your church, yet perhaps it has been some time since the windows were properly inspected. Even the simplest stained glass designs are subject to degradation and must be evaluated every decade or so to ensure the continued health of the windows for the inspiration of future generations of worshippers. Left to deteriorate, priceless pieces of carefully inspired and crafted artwork can be destroyed by neglect.

So, how do you know whether your stained glass needs attention or not? Do a personal inspection tour. Here's what to look for:

If lead has been protected and given preventive maintenance over the years, the lead cames should not require replacement for at least 100 years!

Look directly at the lead and try to determine how often you can find breaks in the lead itself. Multiple breaks throughout a window mean re-leading is probably necessary. However, this should happen only in windows 75 or more years old, or in windows that have never had an exterior protective covering.

A bulge is a serious threat to a stained glass panel. This bulging effect may extend inward or outward as much as 3 inches, and, when left unattended, the stained glass in a bulging panel will crack and break, stretch the lead, and eventually fall out of the frame. This is caused by the great weight of the stained glass, missing cement, deterioration from weather and poor bracing. 

Observe the window from the interior and look up. Try to determine if the stained glass window is vertical, or if it has one or more areas forming a rounded curve (or folding effect), either inward or outward.

Simply focus on each panel, looking for bulges and then move to the next panel, and so on. If the windows are vertical, that is good. If you see bulges of at least 1 inch from vertical, the process is already underway for glass to start breaking under stress, the lead loosening and breaking, and eventually you may lose the windows.

Steel braces, usually the width/length of the stained glass panel, are used to secure the stained glass panel of lead came, glass and cement and keep it vertical. These braces can be both vertical and/or horizontal, and sometimes at other angles.

Most modern braces are flat and rectangular, while 100-year-plus windows have rounded braces tightened at the joints by wire. They are soldered at the lead joint areas or wired tight and then secured at both ends into the window frame. Bulges are typically avoided in stained glass panels where bracing has been properly placed and remains tightly secured.

From the interior of the stained glass window, take hold of each brace to check for movement. No movement is good. Check both ends of the brace to see if it is firmly attached to the frame.

Also determine if the original solder is holding at the lead joints crossed by the brace. Loosened horizontal braces, prior to a bulge developing, can be corrected relatively easily, but must be addressed or other problems will begin to occur.

Obviously, glass can be broken and improperly painted/fired glass can deteriorate. Nothing bothers a person sitting in the pew more than seeing a broken piece of glass letting gleams of light pour through. A close rival for irritation is a badly mismatched repair, where now a green piece of glass is located where a brown piece was originally.  

Look at each individual piece of glass to see if you can spot cracks, breaks, bullet holes and badly mismatched glass.

A word of caution: stained glass is very hard to match, even by those who say the match will be perfect, so to ensure a better match, leave as many pieces as possible if they have only one or two minor cracks. Those with multiple cracks easily visible from the congregation will need attention. 

Typically, the first element of stained glass to deteriorate is the cement between the lead came and the glass. Much like the preventive maintenance of an automobile requires changing the oil every 3,000 miles, stained glass should be re-cemented every 20 years or so.

The re-cementing process is a simple and time-tested one of applying a cementing compound to the exterior (possibly with a paint brush) and then rubbing the surface with a rag or brush, leaving the new cement to intermingle with the old.

The results are re-strengthened, somewhat water-and-air-tight joints, and brilliantly clean exterior windows. Re-cementing is a critical preventive maintenance step for the continued health of your stained glass. 

While standing on the interior side of the stained glass, press firmly and directly on the center of a lead joint near the middle of a stained glass panel. If you get movement or hear even a soft rattling sound, re-cementing is needed.  

Protective Covering
Protective covering is also important to evaluate as it is indispensable in guarding stained glass against the elements and external threats. When inspecting protective covering, look for four things.

First, is the protective covering now "ugly" and detracting from the overall appearance of the church campus? Second, are there broken pieces? Third, is the window still sealed, or is water seeping in, causing rot and condensation problems? Finally, if your church has wood rather than stone frames, inspect the paint and caulk between the stained glass and the protective covering to determine its condition.

After the Inspection
If you find bulges, soft cement, loosened steel braces, broken glass, or damaged protective covering, contact professionals for their suggestions and costs. Having these needs properly and quickly addressed will determine the long-term health and beauty of your stained glass, enabling congregants now and in the future to enjoy God's story through God's light.
This article is excerpted from "The Stained Glass Appraisal Guide," by the late Dr. Gary Gray and Carrie Crow. Crow is the vice president of research and communications for the American Consultation on Stained Glass,

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