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Why some films turn foggy after some time?

    Why some films turn foggy after some time?

Many people complain their films turn foggy after a few years, why?
Let’s look at some basic film construction points.

 The above photo is a typical film construction diagram
  1. Release liner
  2. Mounting adhesive
  3. PET
  4. Laminating adhesive
  5. PET
  6. SR Coating.
There are two important components we have to mention, the IR absorber and the UV inhibitors, we hear them very often, and we all understand well what those thing do, they absorb or reflect away heat and the UV ray.
But where do we place then? This makes a huge difference. Pretty sure, we all got different answers.
The correct way is to infuse the UV inhibitors with the mounting adhesive, because they are the first layer to get in contact with the sunshine after it penetrates the glass. So the first PET-closest one to the glass is protected from UV rays and to prevent the color fading or become foggy.
 
We all know a good film should have a high UV cut, so the color becomes more stable, The theories is simple, but UV inhibitors are every expensive, so some cheap films will apply a Fluorescent agent to substitute the UV inhibitors, the price of which is only 1/3, so this is somewhere to cut corners.
 
But a new problem will appear, the Fluorescent agent does not get along well with the mounting adhesives, not like the UV inhibitors, Well, there is another way, -let’s put the Fluorescent agent between the second PET and the SR coating-5 and 6. So now you have a film with nearly 100% UV cut.
 
Problem is-after sometime, the Fluorescent agent become blurry and the first layer of PET is not well protected by the UV inhibitors mixed within the mounting adhesive-they begin to look foggy.
 
So, you know one possible way, why the films can become foggy.
When choose a window films, make sure you know the basic construction and make sure the films is a good quality and can last for a long period of time.