🧵 Sunglasses, UV Light Typing, Testing, and Selectively Blocking Materials

Anonymous at Sat, 27 Apr 2024 17:31:44 UTC No. 16148686

I want to buy some test cards to verify the capacity for sunglasses to block UVA, UVB, and UVC radiation. When I look online for test cards which have designated testing zones for each of these types of radiation, I find that I can only find cards which have testing zones for UVA and UVC (as pictured), and other, more expensive UVB-specific test cards.
What I want to know is whether it is practically possible for sunglasses which block UVA light to fail to block UVB light. As far as I can tell, the materials which typically are said to have this property are metallic pigments that are used in sunblock.
What methods do sunglass manufacturers use to block UV light, and how likely do you believe it is, given these methods, that sunglasses bought online might have the ability to block UVA but not UVB?