If Samin Nosrat were a beauty writer and not a chef, her wildly popular cookbook and subsequent Netflix show Salt, Fat, Acid, Heat might have been called Hydrators, Smoothers, Sealers. And instead of being about food, it’d be about moisturizers. Swap Samin making focaccia in Italy for Samin traveling to Switzerland to find out exactly why Weleda Skin Food is so rich; a trip to Japan to explore miso becomes a ceramide-centered Korean adventure. Are you listening, Netflix? This is great stuff! It works because, like every really delicious dish, moisturizers can be broken down into just a few components. Drugstore and luxury moisturizers all have these crucial elements, and it’s the balance among them that makes one moisturizer better for certain skin types, go cult-classic, or not really do the job right. Ingredient lists might be long, but most moisturizers aren’t actually very complicated. “With moisturizers overall, you should look for the basics,” says cosmetic chemist Marie-Veronique Nadeau, whose ingredient know-how makes it easy to sort through the different categories. Let’s start with…
The Hydrators
“Humectants increase the water content of the skin,” says Nadeau. And usually, moisturizers have a cocktail of a few humectant ingredients. “Hyaluronic acid is a popular one since the molecule can hold up to 1,000 times its weight in water,” she adds, while citing other examples like glycerin, propanediol, and honey. Another source of hydration is Natural Moisturizing Factors. “NMFs are how your skin actually maintains moisture levels in its top layer,” Nadeau explains. You might have never heard of them before, but saccharide isomerate, urea, sodium PCA, and amino acids are all examples of NMFs that aid in hydration. And finally, some exfoliating acids also function as humectants, and they might be in your moisturizer at relatively low levels. Look for water-soluble AHAs like glycolic, lactic, and mandelic acids—not BHAs. Those are oil-soluble, and don’t attract water like AHAs do.
The Smoothers
“Emollients round out a moisturizer,” says Nadeau. Unlike water-based ingredients, emollients stay on top of your skin to smooth out its surface and keep it soft. Because they stick around, emollients also help the hydrators you’ve coaxed into your skin from evaporating too quickly. The best emollients are barrier lipids like ceramides and fatty acids. “Those lipids make up the skin’s protective barrier layer and maintain its function. They are a must-have in my book to truly moisturize the skin, reduce flaking, and restore suppleness.” But they’re not your only emollient option! Tocopherol, otherwise known as vitamin E, is an emollient with antioxidant properties. Oils also act as emollients—my favorite is squalane, which mimics the oil your skin makes called sebum. And, in oil-free lotions, you’ll probably find a silicone-based emollient instead of an oil-based one. Nadeau notes that silicone-based emollients like dimethicone are often used in skin creams because they glide on and smooth everything nicely.
The Sealers
“Occlusives stay on the surface of the skin and slow evaporation,” says Nadeau, which is technically what emollients do, too. This isn’t a hard and fast line, but what separates lotions from rich creams is heavier occlusives like petroleum jelly, beeswax, lanolin, and capric/caprylic triglycerides. The thin film left behind by an emollient might be enough if your skin is oily—otherwise, a true occlusive will help you hold onto water the longest, helpful when your skin is dry or sensitized. “Very heavy occlusives like petrolatum can cause comedones,” warns Nadeau, who instead prefers a natural occlusive like cholesterol. It’s the thickest of barrier lipids (remember those from earlier?) so it works synergistically with your skin.
Of course, there are a lot of other ingredients in moisturizers that don’t fall within these categories, like skin-soothing extracts, necessary preservatives, and strength-building proteins. But once you understand the major categories, you can break down all moisturizers into a super simplified recipe. That makes it easier to decode a new product, or find a thread through a few your skin already likes. Skin Food becomes glycerin + sunflower seed oil + lanolin, which means it’s great for super dry skin and not so great if you’re vegan or allergic to wool. My favorite Cerave cream might boil down to glycerin + ceramides + cholesterol, which shakes out to be pretty comparable to Drunk Elephant’s Lala Retro Whipped Cream. Both are good rich, but not too rich, options that wear easily in the winter or overnight. Tatcha’s Water Cream is easily read as glycerin + dimethicone, skipping the occlusive category for a hydrating gel texture that’s ideal for oily skin. Are you getting the idea? What’s your moisturizer recipe?
—Ali Oshinsky
Photo via ITG