When it comes to cosmetic formulations, not all are created equal. However, there are some generally accepted rules as to what function certain types of products are supposed to perform and what ingredient types you’ll need to accomplish those functions. Keep in mind that some ingredients will cover more than one of these functions.
A moisturizer typically contains three kinds of base ingredients that perform its function of hydrating the skin:
Emollients are smoothers and they function by temporarily filling in the fine lines and wrinkles of your skin. This not only helps improve the appearance of these imperfections, but it also improves the feel or texture of the skin. Emollients also help the product spread over skin evenly.
Humectants operate by actually drawing outside moisture to the skin thereby hydrating it. Moisture often has a “plumping” effect on the appearance of skin, so these products also make the skin look more supple.
An occlusive agent helps retain moisture on the epidermis by creating a barrier that prevents moisture from escaping by way of evaporation. Occlusive Agents can also help resist environmental oxidative damage caused by pollution because of this barrier function. These ingredients have molecules too large to penetrate into the deeper layers of skin.
It may seem formulaic, but with so many ingredient possibilities, real world products are far from cookie-cutter.
For example, because my skin is more oily than most, I tend to gravitate to lighter-feeling moisturizers with a lower ratio of occlusive agents to emollients because my skin already does a pretty good job of hydrating itself. Because of this, too much of an occlusive agent can feel greasy on my skin. However, a lot of people with chronically dry skin swear by mineral oil or coco butter which have powerful occlusive properties. The simple act of retaining the moisture they would quickly lose otherwise keeps their skin from getting dehydrated.
You might also wonder about additional active ingredients that improve the function of skin (like Retinoids, antioxidants, and Salicylic acid). These ingredients can further personalize the effectiveness of a favorite moisturizer while simplifying your skin care regimen. However, if you’re prone to finicky issues that alter from lackluster appearance to the occasional breakout, you can layer a serum designed to treat your trouble-du-jour underneath a good basic moisturizer. This way, you can more easily personalize your favorite one to suit your daily issues.