Have you ever wondered why you’re always told to apply sunscreen 15/20 minutes before sun exposure?
Cos if you’re anything like me, you’ve often put it on 5 minutes before leaving the house. Aham… What can I say? Girl’s busy…
But does it matter – as long as you put it on in the first place, I mean?
Yep. There’s a scientific reason why you need to put it on 20 minutes earlier… and it has NOTHING to do with sunscreen activation.
Sunscreen Activation Is A Myth
Rumour’s going round that mineral sunscreen (i.e., those with zinc oxide and titanium dioxide) work straight away while chemical sunscreens need to be activated by binding them to the skin. This chemical reaction supposedly takes 20 minutes.
For the longest time, I believed this rumour. Like you, I was honestly convinced this was the real reason why you need to apply sunscreen 20 minutes before sun exposure. Wasn’t that what even science-bent beauty blogs were telling us?!
Thanks to the research work of Reddit cosmetic chemist Stephen Ko, we know know that’s BS. Both mineral and chemical sunscreens work straight away.
Heck, they’d work even in the bottle – if the bottle were transparent and UV rays could get through.
So that’s definitely NOT the reason why you need to apply your sunscreen 20 minutes before sun exposure. But what the heck is it then?
The Real Reason Why You Need To Apply Sunscreen 20 Minutes Before Sun Exposure
Think of sunscreen like self-tanner. If you don’t distribute it evenly, you’ll tan in spots. Some areas will be darker and others lighter.
Sunscreen works the same way. If you don’t apply it evenly, you won’t get the same protection everywhere.
It’s not just a matter of applying the same amount on every area. You need to give it time to dry and form a uniform film on your skin.
If you don’t disturb it…
The “sunscreen must bind to the skin” myth isn’t totally false. It’s true this binding process DOESN’T activate your sunscreen. BUT it does help it adhere better to your face.
Have you ever touched self-tanner/paint/nail polish while they were still fresh? If you did, you know you’re removing some of the pigment and you need to touch it up again.
Sunscreen works like that. If you rub your face, sweat and even apply makeup before the sunscreen has had time to dry down and form the protective film on your skin, you’ll likely removing some of it, compromising the protection you’re getting.
So don’t touch your face (and any other area where you’ve applied your sunscreen, of course) for at least 15 minutes, ok?
By the way, if you’re curious to know what my fave sunscreens are, check out these guides below:
The Bottom Line
If you want to maximise the protection of your sunscreen, always put it on 20 minutes before sun exposure. You won’t get even protection everywhere otherwise.
How often do you wait after sunscreen application to leave the house? Share your story in the comments below.