What is a Surfactant?
Surfactant is short for “surface active agent”. It’s molecular structure, in simple terms, is made up of a head and tail. The head is water loving and the tail is oil loving. Which basically means it’s an emulsifier – something that brings oil and water together.
Surfactants are also detergents, they foam and lather up to remove oil and dirt from your skin or clothes. Most surfactants are considered “mild cleansers”.
There are four different classes of surfactants, which is why you see multiple surfactants used in one recipe, as they bring different properties to the formulation, a well balanced recipe will always include at least two different surfactants.
Anionic
These bring lots of lather and foam, but they can also be irritating which is why you need to add other ingredients for mildness. Anionic surfactants have a negatively charged water-loving head. They’re the most commonly used surfactants due to their ability to create high foaming, bubbling and high cleansing products such as shampoo, body wash and bubble bath. Anionic surfactants include :
- Sodium Cocoyl Isethionate (SCI)
- Sodium Lauryl Sulfoacetate (SLSa)
- Disodium Laureth Sulfosuccinate (DLS Mild)
Amphoteric
These add mildness and viscosity, but they’re less foaming than the anionic which is why you normally see amphoteric and anionic surfactants together in recipes. Amphoteric surfactants can be either positive or negatively charged depending on the pH of your finished product. Amphoteric surfactants include :
- Cocomipropyl Betaine
- Lauryl Bentaine
Non-Ionic
These have no foaming capabilities which is why they’re not commonly used as the main surfactant. They’re great for using as emulsifiers, but can slightly reduce the foam from other surfactants. They are a gentle cleanser and have the capability to be used as an emollient, softening the skin. Non-Ionic surfactants include :
- Decyl Glucoside
- Cocamide DEA
- Polysorbates
- Emulsifying Wax NF
- PEG ingredients
Cationic
These are generally found in conditioning ingredients. Cationic surfactants have a positively charged water-loving head, which means they are the opposite of anionic surfactants. Because of their positive charge cationic surfactants have lot’s of skin nourishing benefits. They will reduce the foaming of your recipe so are generally only used in small quantities (around 1-3%) in recipes like conditioner where foaming is not necessary. Cationic surfactants include :
- BTMS
- Polyquat 7
- Honeyquat
- Cetrimonium Chloride
In summary, an anionic surfactant will offer good bubbles, foam, and lather but might be a little harsh. So we add an amphoteric surfactant to the recipe to make it milder and thicker. I like to add a cationic surfactant to my hair products to offer some conditioning at about 2 to 3% maximum, and I’d include a non-ionic surfactant if I had a large amount of oil I wanted to emulsify.
What are some basic surfactants to get you started?
In my workshop I always have a few different surfactants on hand, they’re the ones I use in several different recipes – my go to surfactants!
SLSa (Sodium Lauryl Sulfoacetate)
This comes in a very fine powder form (the powder is so fine it’s actually a good idea to wear a mask when using it so you don’t inhale too much powder.) It’s a mild cleanser and provides tons of bubbles and long lasting foam which is why you see it in all my bubble bath recipes – like my foaming bath truffle recipe. SLSa is derived from coconut and palm oils which means it’s 100% of natural origin, unlike SLS (Sodium Lauryl Sulfate), which is produced in a lab by combining lauryl alcohol (from petroleum or coconut oil) with sulfur trioxide gas or chlorosulfuric acid.
Cocomipropyl Betaine
I’d say this is an essential ingredient for anyone who wants to formulate their own body products. It has good foaming properties, with good flash foam, lather and bubbles. It helps to reduce the harshness of other surfactants. It’s also a good anti-static for hair which is great for someone like me who has a serious problem with frizz! It’s not a great cleanser, but that’s why we use it in combination with other surfactants.
Emulsifying Wax-NF
This comes in pellet or flake form and has a waxy texture. Emulsifying wax offers emulsification (combines oil and water) with the addition of emolliency so your lotions will have a bit of slip and glide. Used in recipes around 3-6%. A must have for making things like lotions, creams and other recipes with a high water content.