Sun through glass

[Deck]

Is it possible to get any kind of tan effect through glass - i.e. a car windscreen? If not, why not?

[Rabelais]

No, most glass unless very specially made is impervious to UV light making it impossible to get a tan

[seb brown]

I remember being suprised at getting a tan just on my right arm, which had been resting for ages on the door of my car on a long journey. The window wasn't open. Truck drivers also get a tan on one arm for the same reason. It was even mentioned on the Simpsons once, when Homer was being a truck driver!

[Gef]

I agree with Ravelais, truck drivers get a tan on one arm because they always have the driver's window open.

[sft42]

Having spoken to a optician who knew about this, only the windscreen on a car has an inbuilt full UV filter which is why "reactilight" type glasses don't darken down properly if worn while driving...the side windows are more like normal glass which doesn't have any built in filters but does stop a lot of UV but not all.....over time a tan can be built up through a closed car or truck window.

[Chinajan]

If you can't tan through glass, what happens when you lie on a salon type sunbed then?

[Rabelais]

I believe I said unless it was specially made glass, which is obviously what you would use if you want UV light to penetrate. So that is what gets used in sunbeds. As to the translucency of normal soda glass and window glass to UV light a small amount of UV-A penetrates and virtually nothing from the higher end of the spectrum. As to the level of tan you would be expecting to get in these conditions, it is about the equivalent of slapping a thickness of sunscreen the same thickness as that of the glass and lying out. You might get a tan but you'd be much more likely to see the sun disappear over the horizon.

[Chinajan]

Yes, the evidence to hand supports your belief. Thanks for that.