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.
SPF rating is subjective at best and not a regulated term in many countries.
Australia is a place where it is a regulated term and a test by Choice showed that 16 of 20 products failed their rating and several have since been recalled.
https://www.choice.com.au/health-and-body/beauty-and-personal-care/skin-care-and-cosmetics/articles/sunscreen-testBack to your original question which is answered in the article
In percentage figures that means the difference between, say, an SPF 50 sunscreen and an SPF 30 sunscreen is less impactful than you might assume. An SPF of 50 protects you from all but 1/50th of UV rays (98%), while sunscreen with an SPF of 30 protects you from all but 1/30th of UV rays (96.7%).
No way! So like I’d be be paying exponentially more for an additional 0.6% if I brought the SPF75!
Damn.
Yeah but any power gamer loves this math because that 0.6% is still a nearly 30 percent damage reduction compared to the lower grade sun armor so you’ll be stomping those pubs that don’t persue it.
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Yep. Welcome to capitalism, where the bigger made up number actually mean very little in real terms.
I looked up sunscreen recommendations on Consumer Reports and virtually every sunscreen didn’t perform as well as advertised in CR’s lab tests. CR’s top rated sunscreens all happen to be marketed for kids/babies oddly enough.
You get sunburned: “oh, silly me, I must have forgot to reapply”
Your baby gets sunburned and spends the next 72 hours crying: “I will murder the CEO of Johnson & Johnson”
Good writeup, yo
so if u do two spf 50 layers u should get spf 2500.
but in practice the second layer won’t be as thick…
If you’ve ever used a UV camera it’s pretty clear that much like lotion not absorbing after a certain point, there’s a limit to how dark your skin gets with a given sunscreen. Also that there’s a massive difference between brands and formulas. I had some photos I took with one but can’t find them. If I do later I’ll update.
Searched but couldn’t find them. Did find a conversation though where I used it to show most cars in a parking lot have UV blocking windshields but every other window is transparent unless they have tint
This is one of my favorite videos for showing this in effect: https://youtu.be/o9BqrSAHbTc
Don’t buy American sun screen. It’s always cakey and flakey. Go import some Korean sunscreen. It’s basically feels like you have nothing on and gives you better protection.
There are plenty of great brands of American sunscreen. Just don’t buy the super cheap shit. Which is generally good advice in any country. Some brands that come to mind are Kiehl’s, First Aid Beauty, and EltaMD. To be clear, I love me some Korean skincare, and I think it’s superior to American. I just don’t agree with your premise that all American sunscreen is “cakey and flakey.”
I just looked it up and America will soon get the good sunscreens. Bemotrizinol has just been FDA approved.
Until then, I am sticking with American has some bad sunscreens. Until I guess this month.
Neutrogena works great and feels great. That’s why it’s more expensive.
Us has 16 of uv filters aproved, whereas EU has 30+. Last UV filter aproved by FDA was in 1999. So us had old sun screens
I didn’t know that. Thanks for the info.
By god I think you’ve cracked the thing.
