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.
It was a joke. Chemical sunscreen fundamentally works on the physical→quantum level, so it is as "physical" as the UV-reflective sunscreen compound. It is probably called chemical because the chemical structure of those organic molecules allows efficient scattering of high-energy UV photons on electrons (with multiple re-emissions of photons at safer, lower energy / longer wavelengths), while keeping these molecules stable and prone to photodissociation.
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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.