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Originally Posted by bmussatti
Here is a simple test you can always preform to tell if the window (or any glass) has UV protection.
Remember the science stuff we all did in grammer school? Remember the science test we did with two plorizing lenses? When the lenses are parallel, the light goes through, but very slightly less intense. When one lens is turned 180 degress, the polorizing lines are now perpendicular, and no light goes through!
So how can this be applyed to your Boxster?
Take a polorized lens. We all have them if you have a good pair of sun glasses. Take two pair of sun glasses, align them, and the light will pass through. Now, turn one pair 180 degrees, and the light will be blocked! This will assure you that you now have a polorized test lens.
Now take that lens, and look through your side window or windschield. Everything should look fine. Now, rotate your head (be careful so you don't hurt yourself or hit someting while driving!!). As you rotate your head, if the Porsche glass is polorized, the light will eventually be blocked, as the two polorized lenses become perpendicular.
I hope this makes sense.
Have you ever noticed, when you have sunglasses on, that certain windows and glass in your car looks darker as you tilt your head? Or you see large dark spots, especially in your rear window? That's the polorization of the glass working, and fighting against each other.
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HI,
That is very good reasoning and a very good way to test for
Polarized Glass. But, polarizing isn't the only way to block UV. And, on Modern Cars, it is rarely used, so your test, valid as it is, won't work here.
Take Modern Eyewear for instances, since about 1995, by Regulation, all eyeglasses had to be 100% UV blocking. Yet, these eyeglasses (not Sunglasses) are not Polarized and will fail your test.
Normal Visible Light has a wavelength of between 400nm (Violet) to 700nm (Red). nm stands for
Nanometer, or One Billionth of a Meter - a very small distance indeed. Ultra-Violet Light (UV) has Wavelengths of between 200nm to 380nm.
There are various materials which will block the shorter wavelength of UV while being totally transparent to the longer wavelengths of Visible Light. One such material is a class known as PVBs (Poly-Vinyl Butyls), not to be confused with the dreaded and Toxic
PCBs. PVBs can be made into a film which is then sandwiched between the layers of Glass (in this case Auto Safety Glass) and effectively block up to 95% of the UV light which strikes it. PVBs can also be added to any number of other products, such as Dash Protectants and Waxes and add the same UV blocking qualities to these as well.
The most prevelent PVB Films on the Market today are known by the Trade Names
Vanceva and
Saflex. These are the Films which Porsche's Glass supplier uses. In addition to UV blocking,
Vanceva in particular also aids in blocking light of longer wavelengths, such as Infra-Red (700+nm) which is essentially Heat Energy, so combining this with
Saflex, the Glass effectively blocks much of the Heat which can also adversely affect your Car's interior. Hope this helps...
Happy Motoring!...Jim'99