When I first learned that Glossier was coming out with a deep-cleansing, exfoliating face wash, my first thought was… No. Not for me, thanks! My dry skin has never reacted well to gel cleansers, and also, I’ve always been partial to skincare acids that don’t ask me to immediately wash them down the drain. However, when your job is quite literally testing out new products, you can’t just throw the whole cleanser out with the sink water. I got a lab sample to take for a whirl a couple months ago, and surprisingly, I loved it. The consistency was more like foamy honey, and using it every other night didn’t make my skin feel irritated or tight. Actually, it felt really smooth and healthy. (Reader, by the way, though Glossier does pay my bills no one’s holding a bottle of St. Ives to my face to make me say this.) Obviously, I couldn’t take my surprise and delight at face value—I had to dig into the why with the product development team. And what I discovered is that Cleanser Concentrate actually relies on some really interesting skincare tech: after I rinse, the cleanser leaves behind a totally imperceptible, good-for-skin film that keeps its actives working for longer.

Now, I know what you're thinking… a film on my face is...good? Not only is it good, but as Gerri Molina, Glossier’s Head of Research and Innovation explains, your natural skin barrier “is ultimately the best film," since it keeps the good stuff (hydration) in and the bad stuff (acne-causing bacteria, pollution, the elements) out. Film formers mimic this action, to both support your natural skin barrier and keep active ingredients close to your skin for longer. Formulating chemists have all different types of films to choose from: they can be engineered, naturally derived, flexible, breathable, totally occlusive… In fact, so many ingredients and combinations of ingredients are known to produce films on skin that it’s basically impossible for a layperson to spot them on an ingredient list (and just because you don’t “feel” a film on your skin doesn’t mean it’s not there). One sneaky suggestion from Gerri is to look on its label for a wear time. A product claiming to work for a specific amount of hours is likely using some sort of film former. Another clue is the word “tightening”—certain types of films contract as they dry, which gives skin the temporary appearance of decreased laxity. But for newer skincare launches, brands are likely to just say they use film formers straight up.

You’ve likely noticed this kind of language when brands talk about moisturizers. High molecular weight hydrators sit on top of skin instead of sinking into its deeper levels, so they’re considered film formers. The Inkey List’s Polyglutamic Acid Hydrating Serum, for example, is described as leaving “a thin breathable film on the surface of the skin.” Heavy, occlusive oils can also act as film formers, since they trap and lock moisture into skin.

But while films are a no-brainer for creams and serums, film forming cleansers are a pretty new concept. “Ideally, an oily film is not something you’d want your cleanser to leave behind,” says Gerri, since that kind of residue prevents water-soluble materials from penetrating through. (Imagine applying cling wrap to a bowl of cake mix before dropping in your ⅔ cup water—it’s kind of like that.) On the other end of the spectrum, harsh cleansing ingredients (particularly in no-rinse cleansers) can leave a sticky residue that traps acne-causing bacteria. Cleanser Concentrate takes a totally different approach. Instead of leaving behind oils or harsh surfactants, “It actually leaves a film of amino acids, which are building blocks for proteins naturally found in skin,” explains Gerri. “After you cleanse, they form a moisturizing film to hold onto skincare goodies instead of washing them down the drain.”

Film forming innovation is happening elsewhere in the beauty department, too. Every sunscreen has some version of a film—they are responsible for waterproofing, adhering sunscreen filters to skin, and creating a continuous coat of protection. Especially considering the ozone’s already got holes, you don’t want holes in your sunscreen application, too. Many color makeup products credit water-based films for comfortable, flexible longwear throughout the day. Gels, mousses, and mascaras use flexible films to prevent formulas from breaking down and flaking off during the day. (“The one we used in Lash Slick called pullulan, and it’s actually what Listerine uses to make those melty breath freshening strips,” reveals Gerri.) And films even exist to deter dirt and pollutants from sticking onto skin. Those are often utilized in hand creams.

The takeaway to all this? Sometimes your skin barrier needs help to keep your beauty products working harder for longer, and nothing does that better than film formers. While AHAs and antioxidants cozy up to my skin for the rest of my day, I’ll be thinking about a world where I apply my skincare on a Monday and it keeps itself fresh and protected till Wednesday. Or something? Hey, a lazy girl can dream!

—Ali Oshinsky

Photo via ITG