Volume 36, Issue 11, November 2001
A Film Review
Finding Window Film’s Place in the Sun
by Dez Farnady
If you expect to find my picks for the Academy Awards you have come to the wrong place. I left Hollywood when I graduated from Hollywood High School in another century, and I have not been back since. This is not a movie review. This is a film review.
I have been in the glass and glazing business long enough to remember all of the bad things we used to say about surface-applied films. We were trying to sell performance glass and looked at the film products as the competition. So, we spent a great deal of time badmouthing a product we did not know a whole lot about.
I first dealt with film people when they had to learn glass product and technical information requirements. I always felt magnanimous, like I was helping the downtrodden and underprivileged. Then one day I got into trouble and had to get a film guy to bail me out, and I have been a believer ever since. It still feels like sacrilege to admit it. I had made a huge glass mistake and ordered some very expensive laminated product in the wrong color.
Saved by Film
In the middle of my crisis I remembered having seen a strange tinted sidelite on a friend’s car some years ago in Hawaii. When I asked him about it, he told me he had the windows tinted to reduce heat gain in the car. The film looked so good I did not believe it was an aftermarket product. So I called my window-tinting friend for help and was I glad when he bailed me out. We tinted all of my clear glass with a white vinyl and it looked absolutely gorgeous. No one could tell the product or the performance from the product specified.
Truth be told, it didn’t matter. It turns out that it was the same product that I was supposed to supply anyway. The only difference was that instead of being between two pieces of glass it was on the inside surface of the glass. It was a diffused white .015 vinyl applied with the same precision as if it were in the lami.
My project was saved by film and all of a sudden I figured that I better learn a little more about this stuff. It offered a lot of other options and applications that might be useful sometime somewhere else. It turns out that the same manufacturers make vinyl for both surface-applied vinyl products as well as for laminate interlayers. The same performance numbers are available with films as are available in laminated glass. One is a fabricator’s, or original manufacturer’s product, while the other is an aftermarket or a retrofit version of the same thing.
Film and Glass
Once the film is applied the performance properties and appearances are darn near the same as that of the similar glass. Tints are available in bronze, gray, white, reflective and even low-E. There is a 50-percent light transmission bronze with a shading coefficient of .57 as compared to a 55-percent quarter-bronze at .73. That is pretty good performance. There are even blues and greens. For applications where re-glaze is not appropriate, films can serve as an effective substitute.
Because they are surface-applied, films are usually on the interior surface. This does pose some minor problems but nothing that cannot be handled if you understand the product. With the perimeter sealants used currently I don’t believe films will contribute to unit failure, but we will still have to deal with thermal-stress breakage.
There are two types of films for window applications—safety film and solar-control film. The solar-control films are designed with adhesives that keep the film attached firmly to existing glass. Solar-control films are typically lightweight at .015 thickness and are applied with dry adhesives. Safety films use thick layers of vinyl, from .040 to as thick as .150, with pressure-sensitive adhesives. Solar films have life spans from 15 to 20 years and when they begin to deteriorate and show discoloration they can be removed easily and replaced.
Clearly, the elimination of an unjustified prejudice against films can offer us another product to enhance and improve the performance capacity of our glass product.
Dez Farnady serves as general manager of Royalite Manufacturing Inc., a skylight manufacturer in San Carlos, Calif. His column appears monthly.
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