Testing sunglasses for UV protection

Discussion in 'Glasses' started by The Central Scrutinizer, Nov 7, 2005.

  1. Hey, all.

    I recently bought a pair of nice Serengeti sunglasses off Ebay. The
    price was _really_ good - like less than 40% of retail. It was cheap
    enough for me to wonder if they might be a knock-off.

    The build quality seems really good; the only thing that would bother
    me about them not being 'real' Serengetis would be the actual quality
    of the UV protection they offer. I understand the issue about
    sunglasses with bad UV being worse for your eyes than not wearing
    anything, because they cause your pupils to dilate and let in more UV
    that way.

    Is there a home-brew way I could 'test' the UV protection of these
    things? Maybe some test involving chemical reactions to UV light of
    some compound I could lay my hands on?

    Thanks!!

    BD
     
    The Central Scrutinizer, Nov 7, 2005
    #1
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  2. The Central Scrutinizer

    Mark A Guest

    All sunglasses by law must have UV protection. That is no guarantee, but it
    is unlikely that it lacks the UV protection you want.
     
    Mark A, Nov 7, 2005
    #2
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  3. Dark-tinted plastic lenses are pretty good UV filters, even without coatings.

    Interesting; that's pretty much opposite of views I've read which
    prompted me to ask the question. I think the argument is that UV light
    is not affected by dark tinted lenses, at least not to the same degree
    as visible light; the net effect is that if you're behind dark lenses,
    your pupils open up, and let in an inordinately large amount of UV
    light, which can basically mean that 'bad' sunglasses can be worse for
    you than no sunglasses at all.

    Oh well. Interesting regardless. I may call an optician and just see if
    they can test the approximate UV protection of the lenses I have.
     
    The Central Scrutinizer, Nov 7, 2005
    #3
  4. The amount you dilate behind sunglasses (say, from 4 mm to 6) might double
    Oh, okay - well, if that's the case then I just won't sweat it at all.

    Thanks for the reassurance!
     
    The Central Scrutinizer, Nov 7, 2005
    #4
  5. The Central Scrutinizer

    Don Lee Guest

    I think it is harder to find glass or plastics that are not UV absorbant.
     
    Don Lee, Nov 8, 2005
    #5
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