The most popular ingredients in cosmetics are their active substances, about which you can find a lot of information. But the formulation of cosmetics is not only about them. I would like to highlight several types of substances without which the final product would not exist at all. For example…
Surfactants!
Cosmetic products are usually made up of more than one type of substance and would often be immiscible under normal circumstances (such as water and oil). And here is the "time to shine" for surfactants. What are they all doing?
- One of the most important properties of surfactants is DETERGENCE. Thanks to them, for example, cleansers or make-up removers are able to absorb particles on our skin, and then we just wash them off with water. Or in the case of sebum, the surfactant traps it so water can wash it away. After all, grease is fat, normally insoluble in water.
- As I already mentioned, they mix immiscible liquids and form an emulsion. So they are emulsifiers. Thanks to this, our creams are able to transfer oily substances to the skin.
- They prevent substances from settling at the bottom of the bottle, prevent the so-called crushing, clumping of certain components... they simply ensure the uniform dispersion of substances and stabilize them.
- Some liquids also spread poorly on the surface. The addition of surfactant makes it easier to spread, for example, a cream.
- Foam is air bubbles in a liquid, and thanks to surfactants, the foam will be long-lasting - examples of this use are, for example, shampoos or shower gels. Foaming is also key for a cleanser.
Surfactants are surface-active substances. Structurally, they are substances with two parts, each soluble in a different environment, most often it is a water/oil or water/air environment. If there are enough molecules, they form organized structures - micelles of different shapes and sizes. Micelles are responsible, for example, for foaming. The whole principle of their function and movement provides interesting physico-chemical requirements such as surface tension, ionization, intramolecular interactions, etc., which I will not burden you with.
In the INCI list of ingredients of your cosmetic products, you may find substances with names such as:
Potassium Laurate, Potassium Myristate, Laureth-7, Laureth-23, Sodium Lauryl Sulfate, Octyl dimethyl betaine, Dodecyltrimethyl ammonium chloride, Potassium Oleate…
Most of the time, however, you will find mixtures of surfactants in the product, rather than just one of them. The product is thus more complex in its detergent or foaming properties.