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Seal Failure and Window Film
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Insulated Glass Unit
Does Window Film Cause Seal Failure?
There is ongoing debate and controversy amongst the window film industry and the window manufacturing and glass industry with regard to the effects of window film (particularly solar control film) on insulated glass (IG) units. In a nutshell, most manufacturers in the IG glass industry contend that the application of window film on IG units will cause seal failure, and therefore the use of window film negates the manufacturer’s warranty. The window film industry states this is not the case and claims the glass industry is using film application as a red herring to provide “cover” for fabricators who may be producing poorly designed or constructed IG units that are sold under long term warranties (20 years to lifetime). By voiding warranties for IG Units with film on them, glass manufacturers and fabricators shift the financial warranty burden (liability) to the customer or window film installer or window film manufacturer.
Who is Right?
Unfortunately, there is some truth on both sides. With the advent of new sealing methods, most IG Units are made with multiple seals in the unit and use desiccants to retard the migration of moisture into the open space. In time these desiccants can become saturated, and when they can no longer absorb water vapor, the moisture migrating through the seal causes condensation on the glass surface. Condensation is the visual evidence of seal failure. However, it is very possible for an IG unit to have a failed seal situation without exhibiting condensation. In such cases, if window film is applied it will absorb and reflect solar energy within the airspace causing a temperature imbalance that may result in increased visible condensation. This leads to the IG Unit owner to assume that the window film application has led to the failure, when in fact all the film has done is expose the defective unit. Thus far the insulating glass manufacturers have presented no factual basis to support their claim that window film universally causes seal failure. In March 2000, under the direction of the Window Film Committee, AIMCAL completed a research study involving a test of window film installed on 6 new commercial (IG) Units. These tests followed ASTM Standards E773 and E774. Associated Laboratory, Wickliffe, Ohio conducted the research. Based on the testing conducted on these units, they concluded “window film had no observable effect on the performance of high-quality manufactured insulating units.” Thus far the insulating glass manufacturers have presented no factual basis to support their claim that window film universally causes seal failure. In March 2000, under the direction of the Window Film Committee, AIMCAL completed a research study involving a test of window film installed on 6 new commercial (IG) Units and 12 residential (IG) Units. These tests followed ASTM Standards E773 and E774. Associated Laboratories, Dallas, Texas and Jim Spetz Testing Laboratory, Wickliffe, Ohio conducted the research. Based on the testing conducted on these units, they concluded “Window film had no observable effect on the performance of high quality manufactured insulating units.” (Readers can review the test procedure in greater detail in the back of the guide. Refer to (IG) Unit Seal Failure Overview).
Two large glass window manufacturers present counter positions on this issue. PPG takes a negative, non-committal position. However, Cardinal IG basically says it “will warrant our insulation glass units against seal failure with the use of these films.” We have taken the liberty to reprint in its entirety, the positions espoused by both companies regarding applied coatings, films and materials of glass. (See Section Sixteen – Seal Failure Overview)
So, Who is Right?
There are still questions to answer. The IWFA and AIMCAL plan additional studies. It seems reasonable from the studies to date to say that newer (0-5 years) properly manufactured and installed (IG) Units should not exhibit seal failure as a result of window film application. The greater unknown is how long an (IG) Unit can keep its hermetic seal in 100% working order. The dealer/installer (and the consumer) should be wary of putting film on an aged (IG) Unit whose warranty will be voided by the manufacturer if film is applied.
Readers are encouraged to review the special publication developed by the IWFA, titled Recommendations For Avoiding Glass Failure to gain an ever greater perspective about the issue of seal failures. Readers will see that there are ways to determine the “operational status” of an IG Unit before undertaking a particular job. Unfortunately, these current methods are neither easy nor inexpensive. However, help may be on the way in the form of new technologies. Aerodyne Research, Inc., Billerica, MA, is reportedly developing a sensor to verify the proper gas filling of insulating glass units to determine if window seal damage has occurred after installation. (The IWFA is always pleased to pass along information of any new developments affecting our industry when it becomes available.)