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What Are Surfactants & How Do They Work in Your Skincare

What are Surfactants and how do they work in your skincare.

I’ve put together some info that will give you an idea of how surfactants work about your skincare (Gian Reew thank you for the inspiration on this one). It should help you recognise these ingredients and compare them to the most common ones found in skincare/cosmetic formulations. I’ll keep it relatively simple (but if I geek out too much let me know :)

I hear people use the words Surfactants or Detergents interchangeably however, they are not the same entirely. Surfactant represents one compound, detergent refers to a completed formulation of which the surfactant is only one aspect of that formula. Surfactants represents a large group of ingredients and can be found in the majority of skincare products. The word surfactant is a shortened from "surface-active agent”.

The easiest way to explain it would be to first discuss surface tension. This is created when two substances are combined (for eg. liquid/solid, liquid/gas or liquid/liquid. The second ingredient of these examples makes the surface of the first liquid create a sort of membrane, which basically means some micro-forces make the liquid molecules stick together.  It’s a chemical that stabilises formulas containing both oil and water by reducing the surface tension at the interface between the oil and water molecules. Because water and oil don’t dissolve in each other, a surfactant has to be added to keep the mixture from separating into layers. 

Surfactants in cosmetics provide one or more of six different functions:

Detergents - Cleansing surfactants in soaps/detergents that are used on the skin/hair for cleansing. These surfactants will draw the oil into the surfactant. Then, when the surfactant is rinsed away holding onto the oil, the oils are rinsed away with water
Preservatives/Stabilisers -  surfactants can be utilised to increase the stability of a product, some have anti-microbial properties and can be used as preservatives.
Foaming agents - Cleansers/shampoos that are in a foam formulation as opposed to a liquid form does not actually have anything to do with its ability to cleanse.  
Emulsifiers - (Moisturising/Wetting)  -  are mixtures of oil and water that are semi-stable and do not separate out into their oil/water layers. The surfactant allows the emulsion to have a blended quality. Examples of emulsions are moisturising creams and lotions. When applied to the skin, the oils are delivered to the skin surface.
Conditioning agents - these leave-on skin/hair-care products remain on the skin/hair, giving it a smooth feel due to the lipophilic (oily) portion of the molecule.
Solubilizers -  these are used when blending a small amount of oil into a large percentage of water. Some examples of products include fragrances and toners. 
There are 3 times of Surfactants:

Hydrophilic - attracted to water/repels oil
Hydrophobic - attracted to fat/repels water
Lipophilic - attracted to oil/repels fats, water

Surfactants stabilise formulas containing both oil and water as they have Hydrophilic, Hydrophobic and
Lipophilic Surfactants. Having these groups makes the surfactant amphiphilic which in turn allows the surfactants to be soluble in water while the hydrophobic group allows the surfactant to be soluble in oils.
The more common Surfactants found in most skin and haircare: (These are all sulfated detergents and some of these are best  to avoid for sensitive skin types)
  • Sodium lauryl sulfate
  • Ammonium laureth sulfate
  • Disodium lauryl sulfosuccinate
  • Cocamphocarboxyglycinate
  • Cocoamidopropyl betaine
  • Alpha-Olefin sulfonate
Not all the surfactants are the same and they’ve been divided into four groups. These are based on the electric charge of the water-attracting part of a surfactant molecule. Positively charged substances are pushed away from other positively charged substances, and are attracted to negatively charged ones. 

We can distinguish the following types of surfactants below:
Nonionic - No electric charge. They are the most often used group of surfactants in cosmetic formulations. These surfactants are often used in thicker products. Some examples are:
  • Fatty acid alcohols such as Cetearyl alcohol or stearyl alcohol
  • Emulsifying Wax NF
  • E-wax
  • Glyceryl Oleate
  • Ceteareths
  • Glyceryl Stearate
  • Oleh, Sorbitans
  • Lauryl Glucoside
  • Polyglycose
  • Ingredients with the prefix PEG.
Anionic - Negatively charges molecules. These are common on the market due to the low cost of production and are generally reactive with other ingredients. Some examples of these are:
  • Carboxylic acids
  • Phosphoric acid derivatives
  • Sulfonic acids
  • Sulfates
Cationic - Positively charged. Cationic surfactants don’t combine well with anionic surfactants but can attach to damaged hair or skin proteins. This characteristic can offer many skin-nourishing benefits. Some common cationic surfactants used in bath and body recipes are your:
  • Chlorides, Stearalkonium,  Centrimonium, and Benzalkonium)
  • Trimethyl Ammonium’s 
  • Methyl Sulfates
Amphoteric - Both negatively and positively charged. They are often used as secondary surfactants and have gentle/soothing properties. Their properties can be changed depending on the PH level. In a low PH/Acidic environment, they become nourishing agents for the skin. In higher PH/Alkaline products they increase the foaming process. Some examples of well know amphoteric surfactants are :
  • Coco Betaine
  • Lauryl Bentaine
  • Hydroxysultaines
I hope this helps you get a better understanding of how Surfactants work in your skincare products. If you have any questions let me know and if there’s any other topic you’d like covered let me know in the comments.

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