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Shining A Light On Automotive Window Film Performance

There is a fairly common perception with a number of consumers and some installing dealers that, in order for automotive film on a vehicle to have good performance, it must be darker (i.e. the darker the product, the better the performance). This is absolutely incorrect! Please consider the following:

A lighter density high performance/hybrid automotive film will reduce more incoming solar heat gain than a darker non-reflective automotive film. The Ultra Violet (UV) rejection properties will be identical. There can be variances in glare reduction depending on the density of automotive film that is selected.

If you take a typical 15% non-reflective film, the Total Solar Energy Rejected (TSER) is 40%; the glare reduction is 79% and the UV rejection is typically 99%. If you take a typical hybrid High Performance 35% film, the TSER is 55%, the glare reduction is 57%, and the UV rejection is identical at 99%. By moving to lighter High Performance films, you can offer equivalent or better solar performance than a darker non-reflective film. This option might also be better received by some consumers who, for a variety of reasons, are not enamored with darker films.  This approach is a win/win situation and also offers an upsell opportunity. Plus, where the applicable law regulates densities, more choices are available to you.

Within the automotive market, the trend is continuing with increased sales of SUVs and pick-up trucks. With the availability of factory and privacy glass for these vehicles, there has been a decline in automotive tint sales. With the problem having been defined, there is a solution available to deal with this! Please consider the following:


  • With factory or privacy glass, there is reasonable performance in terms of solar heat and glare rejection. However, there is a real gap in terms of UV rejection with standard glass plus factory and privacy glass. There is reasonable rejection of the UV – B rays but, in terms of the UV– A rays, OEM glass allows a fair amount of the UV-A rays to pass through so the rejection levels are less than stellar! By way of additional reference, the UV– C rays are basically filtered out by the ozone layer. With window film installed, there is typically 99% rejection right across the entire UV spectrum. This is particularly important when it comes to the UV-A rays that have been linked to skin cancer. The effect of these rays is cumulative, and this makes the installation of window film even more important.


  • Passenger vehicles are built on a passenger vehicle frame; for the SUV and pick-up trucks, they are built on a truck vehicle frame and/or have off-road capability (4-wheel or all-wheel drive). For the former, the OEM requirement is for all windows to have a minimum 70% Visible Light Transmittance (VLT]) and, for the latter, the 70% VLT requirement is for the front windshield and the driver’s compartment, right and left, only. The windows behind the driver’s compartment can be as dark as desired, since there is no VLT requirement where factory or privacy glass is involved, provided that the vehicle has dual side mirrors. A significant number of the SUVs fall into one of these categories, in terms of glass type.


  • For SUV and pick-up truck applications, the benefits of adding automotive window film are obvious, irrespective of the type of base glass type. For the driver’s compartment right and left, a high performance film with a density to satisfy legal requirements is suggested. For the other glass surfaces, it is suggested that you recommend a lighter density non-reflective or high performance film. There will be some improvement with TSER and glare rejection. There are obviously advantages to adding automotive window film to maximize the benefits to the consumer or user. It is also reality that the shatter resistant properties of the glass may be improved.


While the emphasis of this article has been on automotive film, the same rationale or logic can be applied to architectural films for a wide variety of applications, including existing flat glass types.