Summer Skin Care

The Very Important Thing to Know About *When* You Should Apply SPF

Zoe Weiner

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Photo: Well+Good Creative
Google “how to layer your skin care,” and you’ll get thousands of results telling you exactly the order in which to apply your products. While there’s some wiggle room amongst the middle steps (it’s up to you and your skin type, for example, whether retinol goes on before or after moisturizer), the beginning and end of the routine are always the same: cleanser comes first, and sunscreen is the last thing you do before you walk out the door in the morning. But according to derms, we may have been living an SPF lie.

Because, it actually depends on which type of SPF you’re using as to when you should apply it. As you probably know, there are two different types of the stuff out there, and each of them work in a totally different way. And that also means that they should be applied at two totally different points in your routine. What to know more? Here’s what to know

What’s the difference between chemical and mineral SPFs?

Think of chemical sunscreens like a sponge, once these formulas sink into skin, they absorb the sun’s rays and break them down so that your skin stays protected. “Chemical sunscreens are made up of chemicals that are absorbed into the skin, where they can absorb the UV rays and create a chemical reaction that changes the UV rays into heat and the heat is then released from the skin,” says New York City board-certified dermatologist Hadley King, MD. You’ll know you have a chemical blocker if the active ingredient is avobenzone, octinoxate, octocrylene, or homosalate.

Mineral sunscreens, on the other hand, act like a shield or an umbrella against the sun’s rays so that your skin is physically guarded from most of the suns rays. These types of physical blockers show up on labels as zinc oxide or titanium dioxide, and they sit on top of your skin to bounce these UV rays off the surface.

When should I apply a chemical sunscreen?

Now, here’s where the confusion starts: Because chemical sunscreens need to get into your skin in order to work, they should actually go on before your moisturizer. “I would recommend not applying occlusive ingredients [those often found in moisturizer] before a chemical sunscreen because this could decrease the absorption of the chemical sunscreen ingredients,” says Dr. King. “Occlusives are oils and waxes—like petrolatum, beeswax, mineral oil, silicones, lanolin, and zinc oxide—which form an inert layer on the skin and physically block transepidermal water loss.”

While you need occlusive ingredients to seal in the previous steps in your routine (like your serums and treatments), this moisturizer superpower can actually make it more difficult to chemical sunscreen filters to get into skin and do their job. To circumvent this, your best bet is to switch up the order of your skin-care routine and layer on your serums, then your chemical sunscreen, then your moisturizer.

When should I apply a mineral sunscreen?

If you’ve always followed the sunscreen-goes-last rule, then you’re pretty much set to keep on keeping on with a mineral filter.  “Mineral sunscreen should be applied last because it reflects light,” says board-certified dermatologist Michelle Henry, MD. Putting other products on top of these physical blockers could dilute them and compromise their effectiveness, says Dr. King, so you’re better off using them to finish off the skin-care portion of your morning routine.

How do I know which one is right for me?

As far as whether to choose chemical or mineral SPF for your own routine, it’s mostly up to personal preference. Derms consistently say that the best sunscreen around is the one that you’ll wear consistently. And if you can’t remember when to apply which product formula, Dr. King offers an easy fix for remembering when the heck you’re supposed to apply sunscreen in this new reality we’ve now been introduced to. “Combination products can simplify this process,” she says. “There are lots of good moisturizers with SPF on the market these days, as well as beauty balms that combine moisturizer, SPF and make-up in one product.” Just be sure you’re using enough of the product to get your daily dose of SPF, and re-applying on the reg.

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