# Testing UV-blocking of sunglasses

**URL:** <https://boards.straightdope.com/t/testing-uv-blocking-of-sunglasses/451910>\
**Category:** Factual Questions\
**Created:** [June 5, 2008, 5:36pm UTC](https://boards.straightdope.com/t/testing-uv-blocking-of-sunglasses/451910 "2008-06-05T17:36:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\
**Post date:** [June 5, 2008, 5:36pm UTC](https://boards.straightdope.com/t/testing-uv-blocking-of-sunglasses/451910/1 "2008-06-05T17:36:58Z")

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Do I remember correctly that you can test the UV-A and UV-B blocking abilities of sunglasses by looking at a blacklight through them? I tend not to blindly trust labels on $15 sunglasses.

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [June 5, 2008, 5:44pm UTC](https://boards.straightdope.com/t/testing-uv-blocking-of-sunglasses/451910/2 "2008-06-05T17:44:51Z")

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That doesn’t sound right – you can’t see UV B anyway. A better test would be to place the sunglasses between a UV source and something that glows under UV – a blacklight poster, day-glo paint, a coating of sodium salicylate – and see if it stops glowing with the glasses in the way.

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**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\
**Post date:** [June 5, 2008, 5:50pm UTC](https://boards.straightdope.com/t/testing-uv-blocking-of-sunglasses/451910/3 "2008-06-05T17:50:50Z")

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That might have been what I remembered. I knew the details were fuzzy, searched Google but nothing looked useful.