There is a lot of information to learn about surfactants so I have done my best to make this as simple as possible while providing some information so you can make informed decisions.
Surfactants have a bad rap in the cosmetics industry, mostly the clean beauty products. They have their reasons for this though, but not all surfactants are bad!
Surfactants have many useful applications in the cosmetics industry. They are used for cleansing, foaming, thickening, emulsifying, solubilizing, penetration enhancement, anti-microbial effects, conditioning and other special effects.
They are compatible with both water and oil which makes them so useful in cosmetics.
Some surfactants are very harsh and cause irritation to the skin while others are completely harmless.
For cleansing, surfactants pull away the oil from the natural sebum produced in the hair follicles. Rinsing alone only removes the dirt on the surface but not the oil buildup in the sebum.
For foaming products, the air bubbles are surrounded by thin layers of liquid, and the surfactants help stabilize the bubbles that are formed, creating foam. It’s important to note that foam doesn’t really contribute much to the removal of dirt but consumers like it.
It is used as a emulsifier to blend oil and water together in a product. Most creams and lotions are are created using an emulsifier.
Most emulsified products are opaque. There are surfactants that have the ability to create particles so small that light passes through them and the solutions remain clear. Molecules that do this are solubilizing surfactants. They are used to blend oily materials like fragrances or natural ingredients into clear solutions. An example would be a surfactant like Polysorbate 20.
Since surfactants often contain an “oily” part on their molecule, they have conditioning properties that can improve the feel and look of the surfaces of skin and hair. For them to work this way, the surfactants have to be left behind and also be non-irritating.
There are 4 types of surfactants.
- Anionic
- Cationic
- Amphoteric
- Non-Ionic
Anionic is the most commonly used surfactant found in cleansing products. The reasoning for this is because the anionic surfactant’s primary functions are creating high foam, high cleansing, and high washing capabilities in a finished product. They have a negative charged water loving head. Examples of anionic surfactants are Sodium sulfates, Ammonium sulfates, sulfosuccinates, sarcosines, sarcosinates, isethionates, and taurates. These are also the most irritating to the skin surfactants. If you are looking to create a handmade recipe, best to avoid this one and choose another category. Sometimes they are modified to create a less irritating version called ammonium laureth sulfate.
Sulfonic acid surfactants are generally more mild than sulfates. They include Taurates (derived from taurine), Isethionates (derived from isethionic acid), Olefin sulfonates, and Sulfosuccinates. The reason they are not used more often is that they are more expensive to produce and do not provide a significant enough benefit over Sulfates.
Cationic:
Cationic surfactants are those that have a positive charge on their polar head group. They are most useful for conditioning cosmetics. They include chemical classes such as Amines, Alkylimidazolines, Alkoxylated Amines, and Quaternized Ammonium Compounds (or Quats). They are not typically compatible with anionic surfactants and can also be irritating.
Amphoterics are the second most commonly used surfactant. It has the capabilities of a negative or positive charged depending on the end pH level of the product. When paired with an anionic surfactant, the amphoterics surfactants will mellow the harshness of the anionic surfactant. It has a very gentle effect in products which is why they are often used in baby shampoos and other cleansing products that require mildness. The drawbacks are that they do not have good cleansing properties and don’t function well as emulsifiers.
Some examples of well know amphoteric surfactants are Coco Bentaine, Lauryl Bentaine, and Hydroxysultaines, other examples Sodium Lauriminodipropionate and Disodium Lauroamphodiacetate.
Rarely used as a main surfactant in cleansing products, non-ionic surfactants don’t foam like the others do as they don’t have a negative or positive charge, however they can enhance the foam when mixed with anionic surfactants. Due to their gentle cleansing ability, they can reduce irritants from other ingredients in a formula. They also can thicken systems and provide a conditioning effect. Additionally, they are very good for solubilizing fragrances and other natural oils in formulating. Finally, gentle cleansers such as baby shampoos are based on nonionics, the most common of which is PEG-80 sorbitan laurate. Nonionic surfactants are also the primary surfactants used to create emulsions (creams and lotions). This category is still used more frequently due to the various properties it has compared to other classes of surfactants.
The primary nonionics used for cosmetics include alcohols, alkanolamides, esters, and amine oxides.
Alcohols such as Cetyl or Stearyl alcohol are used in creams and lotions to provide body and feel to the formulas. They also help stabilize the emulsions and can reduce irritation. Amine oxides like Cocamidopropylamine oxide are used to boost foam in cleansing products. A number of esters are used to provide conditioning, slip and shine to biological surfaces. Polysorbate esters are also excellent solubilizing ingredients for fragrances and other botanical oils.
Some common nonionic surfactants used in bath and body recipes are your Polysorbates, Emulsifying Wax NF, E-wax, Glyceryl Oleate, Glyceryl Stearate, ingredients with the prefix PEG, Ceteareths, Oleths, Sorbitans, Lauryl Glucoside, Polyglycose, lauramide diethanolamine (DEA) and cocamide DEA and amine oxides such as lauramine oxide or stearamine oxide.
You’ll see that some are irritating, while others are gentle.
Most sulfates have the concern of cross contamination of ethylene oxide and 1,4-dioxane which are know carginogens. A main reason why most companies that produce safe, natural/organic products will avoid them. SLS (sodium lauryl sulfate), SLES (sodium laureth sulfate, PEG-80 sorbitan laurate, (ALS) ammonium laureth sulfate, polysorbates.
Loramide DEA and cocamide DEA are both rated higher on EWG with possible contaminants.
Here is another list of surfactants found mostly in bath and body products. Some already mentioned, some may be new. You can look these up on EWG and google search to learn more about each and decide whether you want this in your products or not.
sodium lauryl sulfate (can be derived from coconuts) Produces High Foam; easy to thicken. Strong Anionic Surfactant; can cause irritation
ammonium laureth sulfate (derived from coconuts) Produces High Foam; easy to thicken. Strong Anionic Surfactant; can cause irritation
disodium lauryl sulfosuccinate (derived from coconuts) Foaming agent, Mild Anionic Surfactant; gentle on the skin
Cocoamphocarboxyglycinate (derived from coconuts) Mild, Amphoteric Surfactant
decyl Polyglucoside (vegetable derived, used in baby shampoos for its gentleness)
cetearyl alcohol
stearyl alcohol
Cocamidopropyl Betaine (derived from coconut oil) Amphoteric Surfactant
Decyl Glucoside (derived from sugar)
Glyceryl Cocoate (derived from vegetables)
Sodium Cocoyl Isethionate (derived from coconuts)
Almond Glycerides (derived from vegetables)
Sodium Lauryl Sulphoacetate (much milder surfactant than SLS)
Sodium Lauroyl Sarcosinate (derived from vegetables and is a natural substitution for SLS)
sodium methyl cocoyl taurate (derived from coconut)
Sucrose Cocoate (derived from sugar)
polysorbate 20 (vegetable derived)
polysorbate 80 (vegetable derived)