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Window Film Iridescence: What It Is, What Causes It, And Why You Might Like The Effect

10 April 2018

Britney Simpson

Commercial window film is manufactured in such a way as to coat the film with a multitude of chemicals for protection and light filtration, or to imprint upon the film for decoration and advertising. What many people are unaware of is that a very specific commercial window film produces a fascinating iridescent effect. The effect is almost always unintended, but fascinating nonetheless. Here is more about what this effect is, what causes it, why you might like it, and how to avoid it if you do not want it or enhance it if you do want it. 

What Thin Film Interference, or Iridescence, Is

Almost all commercial window films are made from polyester. Rather than using really thick strands of this stuff to produce cloth, extremely thin, coated strands are strung together and adhered to each other via machines. This particularly fascinating process creates a film rather than cloth. Quite often, polyester cloth will reflect light at night. 

That is where the commercial film gets its light reflection properties. The polyester film reflects the light, making it ideal for large windows. Additionally, like the cloth, the thin film reflects light at night. The "thin film interference" is exactly that; the film reflecting light. However, in the case of interference/iridescence, the film is actually reflecting and deflecting the fluorescent light hitting the film from indoors, rather than natural light from outside. Fluorescent light produces a very different wavelength of light, and the polyester film responds with this iridescent reflection.

What Causes It

As you now know, fluorescent lighting hitting the commercial film at night is part of what causes the iridescent effect. However, this does not occur on all window films. It only seems to occur on films treated with a scratch-resistant chemical. Any of the windows in your building that are within a few feet of fluorescent lighting and are coated with scratch-resistant commercial window films will produce mild to extreme iridescent effects. 

Why You Might Like It

Who does not like rainbow-tinted windows? They seem so cheerful. It is also a very stunning effect in a vast wasteland of metal buildings and gray towers of the city. The best part is that the iridescent effect also occludes what is going on behind the windows that are affected, creating both privacy and beauty for parts of your building. 

How to Enhance It

If you really like the iridescent effect, you will need to make sure all of the windows on your building are coated with the same scratch-resistant commercial window film. Then place fluorescent lighting within three feet or less of every window. At nighttime, leave these lights on, and you will be able to see the dramatic and colorful effect from outside the building.

How to Avoid It or Prevent It

If you decide that you definitely do not want people to recognize your building by the rainbow-ish windows at dusk and beyond, you can avoid and/or prevent the iridescent effect. Instead of fluorescent lights, use LED lighting tubes. A simple change in the type of lighting you use in your building will change how the windows are seen from outside and below.

If you do not want to give up fluorescent lighting, place the lights more than two yards from the film-covered windows. You can also prevent this effect entirely by requesting that none of the windows have a scratch-resistant film. However, given the nature of ceiling lighting installation in commercial buildings and the fact that going without a scratch-resistant coating produces scratched glass that is difficult to see through, you may want to make these decisions very carefully.

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