Best investment? A slush fund you contribue to reguarly to help pay for the dang thing.

Thanks Jim,

I use Vinylex on the dash with UV protection and I use the sunshade when I park it in the sun, but it's not me I'm worried about. When we carpool and I keep the car, I cover it while I'm at work and put the sunshade in when I park at lunch. My wife drives it every day and if we don't carpool it sits at her office all day with no cover or sunshade. I can see $$$$ flying away as it sits 3-4 days a week in the bright sunshine with no protection. I have tried to get her to cover it, especially to guard against tree sap that eats the plastic window, but she says it's too difficult. I guess we will end up replacing something from sun exposure. When she recovers from passing out over the bill, the cover will become our best friend. I would just like to prevent it if at all possible.

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.

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

Hey Jim:

The test is still valid, and works. I have very new sunglasses and a very new Ford Explorer (rear window). If I turn the sunglasses, I can block out more light, as the polarization become less parallel. Haven't yested in the Porsche, though.

Hi,

As I said, it may work on some older cars, or companies which still use polarizing as a means to block UV, but this is phasing out.

Polarizing is more expensive to manufacture and it reduces the total light transmitted through the glass which can be especially important for nightime driving.

To help combat this, the glass is generally less polarized and so the UV protection is more on the order of 75% or so. It's a trade-off between overall light reduction and UV protection.

I too wear polarized Sunglasses and there is no blocking on the Boxster glass, when rotating them as you mention.

Still, your post was thoughtful and very informative.

Happy Motoring!...Jim'99

Hey Jim:

I bet a few of the forum members here would love to see some pics of you testing the whole polarization theory today with your Boxster!!!! Please send ASAP.

Ha...Ha,

You think I want you schmoes knowing what I look like? I could show you... but then I'd have to kill you... :p

Happy Motoring!...Jim'99