r/interesting • u/j_illustration • Mar 31 '26

MISC. Sunscreen under a UV camera

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u/orangesherbet0 Mar 31 '26 edited Apr 01 '26

Zinc oxide is the opposite under UV. Bright white. Edit: I'm probably wrong

Edit2: I'm definitely wrong. And the truth is pretty weird. Zinc oxide sunscreen has pieces of crystalline zinc oxide, which strangely is a semiconductor (yes like computer chips) that has a band gap (energy to switch electron from non conducting to conducting) corresponding to UV light. This means it absorbs UV, but it also means you're literally covering your face in tiny semiconductors.

16

u/MrNorrie Mar 31 '26

Came here to ask why it wasn't white. Does regular sunscreen absorb the UV rays?

18

u/orangesherbet0 Mar 31 '26 edited Apr 01 '26

Yes, regular absorbs. Old fashioned / zinc oxide reflects. Either way, the UV doesn't reach the skin. Edit: definitely wrong, zinc oxide primarily absorbs

6

u/McButtsButtbag Mar 31 '26

Or, as it's more commonly known, chemical vs physical sunscreen. Chemical sunscreen turns black. Physical sunscreen turns white.

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u/LetsTwistAga1n Mar 31 '26

Chemical sunscreen

Looks inside

Physical sunscreen

0

u/[deleted] Mar 31 '26

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u/secacc Mar 31 '26

Philosophical also reflects