Letters from a Dermatologist · Texture
Mineral or Chemical Sunscreen? How You Put It On Matters More
You're standing in the sunscreen aisle, flipping bottles over. Mineral or chemical? It feels like a big decision. But look closely at the research, and what really matters comes down to three simple questions: how much you use, how evenly you apply it, and how well it comes off at night.
Less Mirror, More Sponge
Chemical sunscreens use molecules that absorb UV light and release that energy as a small amount of heat. Mineral sunscreens use zinc oxide or titanium dioxide, two finely ground minerals.
Mineral filters are often described as tiny mirrors. In lab tests, though, these two minerals reflected only a small fraction of UV light and absorbed most of the rest. So both types work in much the same way: mainly by absorbing UV before it reaches your skin.
These minerals do reflect much more visible light than UV light. That's one reason some mineral formulas can look a little white on skin. It's often called a white cast.
The Amount Problem
In the lab, sunscreen is tested with a fairly thick layer. When 42 beachgoers applied their own sunscreen, they used far less than the testing amount, which likely means considerably less protection than the label promises.
It's actually quite hard to apply sunscreen all over your face without missing a spot. In one study, 57 people were photographed with a UV camera after applying sunscreen to their faces. They missed about twice as much of their eyelids as of the rest of their face.
Fixing the amount can be simple. When people in another study were asked to apply two coats, the amount they used nearly doubled.
Moisturizer Before Sunscreen
You don't need to skip moisturizer to keep your sunscreen working. In one study of 25 people, moisturizing creams applied to their backs just before sunscreen didn't change how much UV the sunscreen absorbed.
When you choose a moisturizer for the morning, a light one that sinks in quickly is easier to work with. Sunscreen can spread smoothly over it instead of dragging.
The Night Shift
Sunscreen is made to stay put, and water-resistant formulas are built to hold on even more firmly. That staying power is great at the beach, but it makes sunscreen harder to wash off at night.
In one study, 20 people washed sunscreen off with water alone, a foaming cleanser, or a cleansing oil. Water alone left more than half of the sunscreen behind. For a water-resistant formula, the foaming cleanser still left over a third behind, while the cleansing oil removed nearly all of it.
By the Numbers
Three Things to Try Tomorrow
- Go for two coats. Apply a thin layer, let it set for a moment, and then add a second one.
- Remember your eyelids. Sweep a little sunscreen over the lids and the inner corners of your eyes, near your nose.
- Try oil first at night. After a day in water-resistant sunscreen, a cleansing oil can lift it off more easily. Massage the oil in, then rinse it off before the rest of your routine.
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