Moisturization? Hydration? How Does It All Work?
Moisture equals water!
Hydrate: To add or take up water
Moisturization is a process that involves hydrating, softening, and creating a barrier to slow down water loss.
There are different categories of moisturizing agents: emollients, occlusives, and humectants
Emollients: these are your lighter oils and esters
Occlusives These are also emollients but they have the ability to form an even water-resistant barrier that slows water evaporation. They are ingredients like mineral oil, dimethicone, fatty alcohols, petroleum, lanolin, stearic acid, beeswax, vegetable waxes, plant butters, and heavy oils like castor, olive etc. The barrier they form varies are not all the same and some perform better than others. Dimethicone, mineral oil and petroleum are believed to be the most effective occlusives.
Humectants: these are ingredients that attract water like Glycerin, Sodium PCA, Betaine, Honey, and Agave.
Film Formers
The ingredient categories listed above form the foundation for the concept of moisturization. However, there is a class of ingredients called film formers that, like occlusives, have the ability to form films on the hair and skin. They include ingredients like hydrolyzed proteins, aloe vera, natural and artificial polymers like plant mucilage, gums, copolymers, and acrylates. These film formers have water-binding properties and hold on to water. Some have humectant qualities that attract water though not as strongly as non-film formers like glycerin.
The concept of moisturization involves hydrating the hair with water and using moisturizing agents
Each moisturizing agent brings something different to the table and this is why they are often used together. Emollients soften the hair, make it more pliable, lubricate the strands and help replenish the oils lost when you shampoo. Humectants attract water and keep the hair hydrated and pliable. Film formers bind water and form films on the hair that slow the rate at which water evaporates from the hair. Occlusives form barriers that reduce water loss and can help maintain the natural hydrophobicity of damaged hair which is more porous than normal.
Different Ones Will Feel Different On the Hair
When you think about moisturizing agents, it is important to know that there are many options to choose from and they will feel different on the hair. Using light emollients and light occlusives (silicones, silicone alternatives) or water-resistant polymers found in gels/mousse will not weigh down the hair as much as heavy occlusives. Humectants also vary in how they feel on the hair…some like glycerin and agave are very sticky while others like propanediol aren’t. They also differ in how much water they attract.
Relying on lighter occlusives or film-formers, are a great option when wearing curls
Why does this matter?
If you have oily hair, you may prefer to use non-greasy emollients and occlusives vs greasy ones. If you are wearing curls, you may choose to use more film formers to reduce water loss instead of heavier occlusives that would weigh down your curls and cause them to be less defined. This is not a hard or fast rule as factors like the size of strands fine/coarse, the tightness of curls, and the amount of product used will impact how your hair is affected. The important thing is that you understand the principle at work so that you choose moisturizing agents that best fit your hair.