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These recommendations are based on solar specifications representing film mounted on 1⁄ 8 ” (3mm) clear glass.

Film To Glass Risk Assessment

In certain cases, the application of window film can increase the risk of glass breakage or seal failure. The age, condition and type of construction of the glazing system can limit or even prohibit the application of window film. The following Film to Glass Risk Assessment Chart will assist you in determining the risk of glass breakage for specific film to glass type combinations. Ultimately, you need to make the final decision as to the total amount of risk you are willing to take with the help of your independent installer.

Regardless of the installation rating displayed on the film to glass installation guide chart, you should only continue if you are aware of the risks and experienced of any of the conditions below exist (We are not liable if you choose to do so) 

1) Any triple or quadruple paned glass
2) Any clear glass 3/8 or thicker
3) Any single glass that is tinted and 1/4 inch or thicker
4) Any IGU Window in excess of 40 sq ft (3.75 sqm) in total.
5) Any IGU with seal failure prior to install
6) Any single pane in excess of 60 sq ft (5.6 sqm) in total.
7) Any glass pan with glass edge dimension greater than 10 feet
8) Any project that is over 2,500 square feet unless you have a written approval
9) Any building with a history of thermal stress fractures or IGU seal failures
10) Any glass that has ANY damage including chips,cracks or scratches
11) Any glass where the film is NOT installed all the way to the edge
12) Any surface that is NOT glass
13) Any glass with paint, lettering or vinyl graphics installed
14) Any textured, bent, patterned, wired glass or skylights
15) Any rounded glass 
16) Any concrete framing or framing that has no gasket or seals
17) Any framing sealant, glazing compound and/or gasket material that is no longer resilient.
18) Any glass experiencing up to 25% of outside shading ay any time of day

Why Glass Breaks Outside Of The Above Possibilties

Window film rarely, if ever, breaks glass by itself. However, window film can exacerbate flaws that may cause the window pane to crack, which happens in less than 1/2 percent of installations. A thorough inspection of the condition of the glass and frames can help determine the risk of installing window film. The common causes of glass breakage are outlined below

Absorbing Solar Energy

Window film reduces solar heat gain into a building by both reflecting and absorbing the solar energy. It is the “absorption” portion that can increase the risk of glass breakage. Absorption causes the glass to heat up and therefore expand more than it would without the film. This expansion, combined with a “flaw” condition, increases the risk of breakage. The flaws are often in the glass, but poor window installation or locations are also common culprits. These flaws are often on the edge of the glass, which cannot be seen when examining a window.

Damaged Edges From Manufacturing

Some common causes of glass breakage cannot be seen before film installation. The edge of the glass is hidden inside the “bite” of the window where a chip or crack can cause a break. Panes of glass are supposed to be ground smooth before installation in a window. This grinding provides a smooth, strong surface that greatly increases the edge strength of the glass. Unfortunately, sometimes when making a window, the manufacturer allows chipped edge glass to be used. It is cheaper than cutting a new piece of glass and they assume you will never know. Any chip or nick in this smooth edge greatly lowers the overall strength of the glass pane. Cracks wil

Badly Installed Windows

Another major cause of glass breakage stems from edge stress from the frame. Glass is supposed to be installed with a little “expansion” space on all sides. If the glass is a little too large and mounted resting on the frame with no spaces, or up against a mounting screw, the edge stress can become too great when sun hits the newly tinted window, causing it to expand. If the glass breaks due to solar thermal stress, the crack usually starts at one of these “edge stress” points


Kepler Window Films has had its architectural products rigorously tested in a manufacturing labs and under extremely stressful environments. The film to glass chart has been applied to over 50,000+ square feet of window film installations to determine the result of this film to glass chart. We have proven that as long as the above rules have NOT been broken, KEPLER window films alone can NOT cause any issues to the glass and KEPLER window films will not be responsible

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