How to test new sunglasses do what they say on the tin?

Supercell · 10-08-2010 12:38AM #1

I really have no idea if this goes here..feel free to move it if not.

So I bought some "Ray Ban" sunglasses on ebay. The seller has a very high rep value but I'm not convinced that these are not knockoffs.

The sunglasses are advertised as polarized and having UV protection.

So science guys, is there any simple tests I can do at home to test they genuinely can do this before I go blind using them in the tropical Irish climate?

csm · 10-08-2010 12:46AM

You can check they are polarising if you have a second pair of sunglasses that you know are polarising.

Hold one of the lenses in your Ray Bans at 90 degrees to a lens in the second pair. It might require a little turning to get it right but if they are polarising then you will be able to get to a point where all light is blocked out.

As for UV, all glass has some UV protection, so its not much of a claim.

Supercell · 10-08-2010 12:57AM

Thanks csm, my concern is that the "glass" may actually be plastic and not have any UV protection at all.
Your polarising test is great though, I can put that one to the test with a friends glasses easily enough thanks.

Capt'n Midnight · 10-08-2010 01:05AM

you can't see UV at 400nm and besides the more dangerous radiation is at shorter wavelengths

you could try UV LED's but the peek wavelength is still in the safe area so having the glasses stop fluorescent colours glowing would prove nothing

you could see if your skin tans under them

or maybe there is a test you could do with fruit ripening or something ??

SkepticOne · 10-08-2010 04:13AM

Supercell wrote: »

Thanks csm, my concern is that the "glass" may actually be plastic and not have any UV protection at all.
Your polarising test is great though, I can put that one to the test with a friends glasses easily enough thanks.

Some sports type sunglasses are deliberately plastic rather than glass. They can still be polarising and have UV protection.

How to test new sunglasses do what they say on the tin?

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