Seems to me like we should’ve easily invented something that lasts indefinitely by now
In: Chemistry
There are two kinds of sunscreens. Chemical sunscreens which are absorbed into the skin. And physical sunscreens, which leave a residue on top of your skin. of of zinc or other minerals that reflect the UV rays away from your skin.
In the case of chemical sunscreens, the chemicals start to break down when exposed to air. So they are only adequately protective for a couple of hours. In the case of physical sunscreens. Moving around, sweat, clothes, etc. can displace the minerals, and leave you with spots that are unprotected. Reapplication every couple of hours solves both problems.
Latest Answers