These creams have some chemical that blocks the UV with some capacity, say a factor of 50. Why can’t I apply two layers of this cream to now get a 100 factor equivalent protection?

I asked the chemist at the store and they said it’s not how it works and that the highest protection factor they have is 75 (which was super expensive).

What gives?

Edit: Thank you for those super informative answers.

  • Jerkface (any/all)@lemmy.caEnglish
    2·
    6 days ago

    Thank you, that is clear.

    You say “better off”, but that doesn’t really account for how easy it is to switch. It’s not like the effort spent grabbing the highest available SPF is taking away from other anti-cancer efforts. I’m not seeing a downside here, though the benefit isn’t as great as I assumed; probably a figure of speech.