Do Scotchtint window films cause seal failure when applied to insulated (double-pane, Thermopane) windows?
No, Scotchtint window films do not cause seal failure. We’ve been applying Scotchtint films to insulated windows for over 25 years with several millions of square feet of film applied to date.
When recommended films are applied to the inside pane of an insulated glass unit, there will be some absorption (except with clear safety films) of the sun’s energy, which will increase the temperature of the glass pane. Some of this heat will transmit to the airspace, slightly raising the airspace temperature. However, even a 20 F degree increase (unusual for most films) will result in a less than 3% change in air pressure, whereas properly made units are designed and tested to withstand 22% changes in air pressure.
Risk of seal failure is greatly determined by the quality of workmanship and the quality of the materials that go into building the insulated glass units. The best guard against seal failure is to purchase well-made units from reputable window manufacturers that have solid experience and histories with insulated units.