Moisturizers have a simple function, to moisturize the skin. There are many products on the market that accomplish this and there are just as many that claim to moisturize, yet somehow fail. One of the main problems is that the science of the raw materials is never explained, nor how they moisturize the skin and hair. In this post, I’ll go over what moisturization is on a biological level and the 3 classes of ingredients that moisturize hair and skin. This is part 1 of 2.
First, I’ll begin with some basics. The skin is composed of 3 layers: epidermis, dermis, and hypodermis (subcutaneous fat tissue). These layers can be broken down in sub-layers, but we’re talking about skincare, not skin cancer so I’ll leave it at that. Moisturization occurs on the upper two levels, mostly the epidermis. Now, what is moisturization? What does it mean to moisturize? This isn’t circular logic, I promise. In layman’s terms, moisturization is hydration and conditioning of the skin for a healthier appearance and healthier feel. On a sensory level, the skin feels hydrated and soft. This is done by either adding water to the skin improving the retention of water already in the skin. There are 3 broad classes of ingredients in haircare and skincare that achieve moisturization. Here it goes:
Emollients: materials that fill that gaps between corneocytes (dead skin cells that cover the uppermost layer of the epidermis). Chemically speaking, emollients are usually fatty acids (aliphatic chains with a COOH functional group) that are building blocks for fats in our bodies. Yes, that includes the skin. This class of moisturizer consists of oils, butters, hydrocarbon fractionations, and petrolatum. Emollients prep the skin, in a manner of speaking, by making the skin soft and smooth. Some emollients like Stearic Acid also function as an emulsifier.
Humectants: these are hygroscopic substances that attract and retain water. In food, they’re used to retain moisture. In cosmetics, they’re used to retain water in the hair or skin and to attract water in the surrounding environment to the hair or skin. Glycerin in the most famous humectant in the personal care field. It’s found in so many formulas. The reason glycerin is such a great humectant is due to its three hydroxyl groups, which will gravitate to water in the hair or skin. What you get from a sensorial standpoint is hydrated and supple skin
Occlusives: for the most part, they’re densely packed hydrocarbon or Silicon chained materials, that when applied on the hair or skin, form a barrier on that matrix. In effect, this barrier restores hair and skin health, reduces irritation, and help retain moisture. Typically, this class is comprised of waxes, some vegetable oils, silicones, petrolatum, lanolin, and mineral oil. There are many natural/green options for the Formulator that wants to stay in that niche. Sensorially speaking, what’s felt more often than not, is the texture of the occlusive. When paired with emollients and humectants, the result can be healthy hair and skin.
Formulating effective moisturizers is another challenge all its own. That will be the topic of the next post. Making pleasant, functional, memorable, and yes, sellable products is as much a science as it is an art. Another aspect of this industry that can be daunting or exciting depending on perspective. Part 2 will be up soon.
Greengen Labs 