Johnson Window Films Dealer Resource Center

JWF, Seal Failure

Seal Failure

Example of Seal Failure

A major debate is currently being waged between glass manufacturers and the window film industry over seal failures. Some manufacturers of IG units assert the application of window film on IG units can cause seal failures. Based on this assertion, many IG unit companies will not uphold their warranty contract if seal failure occurs on an IG unit with window film on it. The window film industry states this is not the case and has conducted research proving this claim to be unsubstantiated.

Seal failures occur when moisture and moisture vapor penetrate the IG unit seals. As earlier discussed, IG units are constructed with solid spacers that separate two or more panels of glass. A sealant is placed around the spacer to help prevent moisture from seeping into the space. Additionally, a desiccant is incorporated into the spacer to absorb any moisture that penetrates through the seal. An IG seal failure occurs
when the desiccant no longer can absorb excess moisture or moisture vapor in the panel space. Once the desiccant becomes saturated, fogging or water droplets become evident inside the IG unit.

IG Unit
The first thing to understand is IG unit seals cannot entirely prevent water vapor from penetrating the space. It can happen because of the natural aging process of the IG unit, or because of a sub-standard IG unit production. Unfortunately, when window film is applied to an IG unit seal close to failure, the absorbed heat within the airspace causes the condensation to be more easily detected on the inside of the IG unit. The misperception is the window film caused the seal failure, but in truth, the film only helped to identify the seal failure problem.

It’s recommended that dealers should exercise caution before applying window film to IG units, especially for units installed before 1995. The Insulating Glass Certification Council (IGCC) was established to promote quality standards in IG unit manufacturing, so it’s a good idea to make sure any IG unit is certified before accepting the job. It’s also a good idea to carefully inspect the unit beforehand. Many glazing systems have weep systems, holes around the seal that drain moisture, so check to see if this system is functioning properly. Usually water stains around the glazing system or building interior provides an indication there might be a problem. You can also test the system by pouring water in the glazing channel to see if the weep system is draining properly.

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