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Protecting Your Stained Glass Tradition

Your stained glass is a beautifully rich and important part of your congregation’s history. The symbols, designs, lead flows and pictorials create an ambiance in which congregants have worshipped and communicated with God over the decades. Many stained glass windows were given in honor of loved ones and serve as memorials that will be seen for generations.

Stained glass is also an extraordinary investment to have in a religious building. Even if the windows are accurately insured, it can be difficult to perfectly repair or recreate damaged stained glass. Matching 100-year-old glass, for instance, can be a tedious process. When broken stained glass occurs, the window might never be historically accurate again. So, the question changes from “How much are the windows worth?” to “What are our chances of loss?”

Why Protective Covering Matters
To lessen the risk of loss, properly installed stained glass protective covering is the best precaution to take. The unprotected window not only deteriorates more quickly, but is almost assuredly going to suffer broken glass over the years.

If you were a robber trying to gain entrance to a temple with two stained glass windows side-by-side, you might note that one is only a single layer of leaded stained glass, while the other has a heavy protective covering. Which would you choose?

Or, if a hurricane is headed your way, which is more likely to have damage to its stained glass – the unprotected stained glass window or the one with a heavy-duty protective covering in place?

The answers are obvious. Protective covering, if done correctly, takes away most of the potential for catastrophic loss. There are still ways the stained glass can be damaged—through fire, for example—but the chances of major loss are greatly reduced if the church or synagogue property committee chooses to protect its valuable artwork.

Protective Covering Options
Historically, glass was used as a protective covering over the beautiful German windows installed between 1885 and 1917. In the 1960s a polycarbonate plastic (primarily the Lexan brand, made by General Electric) was the covering of choice, but the earliest version, while extremely strong, tended to yellow and cloud in a short time after installation. Today, there are several options suited to aesthetic longevity and strength.

Polycarbonate is nearly unbreakable and now remains aesthetically pleasing for about 20-25 years, as opposed to the original polycarbonate, which discolored in about six years. The new advanced product with a UV protective coating is much better, but, being a plastic, will get cloudy and dusty, especially on windows that face the sun.

As it yellows, it also becomes brittle and less effective against damage. Polycarbonate is generally recommended for two situations: protecting highly valued stained glass, such as LaFarge or Tiffany, and in high-risk areas, such as downtown settings or areas prone to hurricanes or tornadoes.

Acrylic, a thermoplastic like polycarbonate, is also shatter-resistant and strong. It is extremely high in clarity and will not yellow. However, it has been known to develop significant cracks and chips within 10 years of installation.

Annealed float glass is used in most business settings and looks nice for a long time if not broken. It is not as strong as the other options and, if broken, will come apart in dangerous shards. If unbroken, it will be taken off only when repair is needed on the stained glass or if the frame (often, the paint) in which it is set is beginning to deteriorate, generally some 30 years down the road. 

Tempered glass is one of two kinds of safety glass regularly used in applications in which annealed float glass could pose a potential danger. Tempered glass is four to five times stronger than standard glass and does not break into sharp shards when it fails.

Tempered glass is manufactured through a process of extreme heating and rapid cooling, making it harder than normal glass. The brittle nature of tempered glass causes it to shatter into small oval-shaped pebbles when broken. This eliminates the danger of sharp edges. Due to this property, along with its strength, tempered glass is often referred to as safety glass. It does not yellow or cloud like polycarbonate.

Laminated safety glass provides the benefits of the long-term appearance of glass, but also protects the stained glass to an extremely heavy blow that might break float glass. The safety glass could break as well, but it will not shatter. It is made with three layers: one layer of plastic sandwiched between two 1/8” glass layers. So, if broken, the plastic layer will not allow it to shatter.

Laminated safety glass is also highly effective in reducing noise and ultraviolet rays. It is commonly used in settings such as schools, airports and museums to reduce outside noise and prevent considerable damage from UV rays to fine furnishings and other valuable objects. Laminated glass can also provide excellent protection against natural disasters such as hurricanes and earthquakes.

A proper venting system should also be employed in the installation of any new protective covering material. Over the past 6 to 8 years, venting has become a widely-accepted practice among stained glass craftsmen. 

Small vents are strategically placed in the framing or protective covering material, allowing air to circulate and avoiding heat build-up, which is one of the leading causes of bulges in stained glass. Vents are screened and typically covered with small “hoods” to match the frame color to keep out bugs, dust and water. 

Making the Choice
When making the choice about which protective covering material to employ, consider if it is more important for your church or synagogue to protect valuable windows, without any fear of outside breakage, or to have long-term outside protective covering beauty.

If a church has extremely valuable windows or is in a vandalism-prone area, polycarbonate, tempered, or laminated safety glass are wise choices. If the windows are less valuable, then simple annealed float glass might be a better, more economical option for long-term appearance.

Regardless of your choice, be assured that properly-installed protective covering is one of the most effective ways to protect and maintain your congregation’s stained glass heritage for future generations.

This information is adapted from “The Stained Glass Appraisal Guide,” by the late Dr. Gary Gray and Carrie Crow Thiele. Thiele is owner of American Consultation on Stained Glass, www.AmericanStainedGlass.org.

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Religious Product News