As consumers become more aware of the ingredients in the products they put on their skin and use in their homes, many have come to view surfactants as “bad” ingredients. In fact, there are numerous choices for natural surfactants in cosmetics, and they work to improve the integrity and performance of cosmetic formulations. Yet conscientious consumers look unfavorably on body, hair and skincare products that contain surfactants, especially Sodium Lauryl Sulfate (SLS). While the scientific evidence does not support the claim that SLS is a cancer-causing agent, the myth prevails and for natural and organic cosmetic formulators, finding natural alternatives is a necessary part of serving your customer base. The good news is that surfactants are the largest class of cosmetic chemicals and offer broad cleansing capabilities. Surfactants also allow cosmetics to slip across, onto or to clean the skin by breaking up and separating from the skin oils, fats, makeup, dirt, pollution and other debris. When you plan your cosmetic formulation, you’ll have a wide variety of options beyond SLS.
What does a Natural Surfactant Do?
A surfactant is a surface active agent.
Surfactants are mixed with oils, waters, and other liquids to lower the surface tension, a prerequisite for wetting, spreading, foaming, and emulsification. Through a chemical process known as adsorption, surfactants change the properties of a substance. The term adsorption means the gathering of gas or liquid in a condensed layer on the surface. This condensed layer creates a film which is why the surface tension is lowered. The chemical reaction which then occurs is the conversing of the liquid and the additional substance, which in turn lowers surface tension.
Surfactants are not always described in their most common form, but rather for the role they play in a formulation. For instance, in recipes in which foam is the finished product, the surfactants used may be referred to as “foaming agents”. Surfactants used in body and hair care recipes may be termed “detergents” or “soaps.” If you’re creating a shaving cream, the surfactants you chose will be for their lubricating and protection properties; they will help protect the skin from irritation and the razor’s sharp edge.
As you create your formulations, you will need a general idea of each group of natural surfactants and how they play a role in your finished product. And, too, you’ll want to understand why the surfactants are grouped or classified together or how/if surfactants work with additional groups of surfactants in a collaborative manner. Not all natural surfactants can work together in the same formula
Categories of Natural Surfactants
Natural surfactants are placed in one of four categories based on their interfaces and charges:
1. Anionic surfactants
Anionic surfactants are most commonly used in foaming products including shampoos and body washes. Their primary functions are to deliver high foaming, high cleansing, and high washing capabilities in a finished product. Anionic surfactants have a negatively charged water-loving head. Anionic surfactants work very well in recipes which have a reaction between a chemical (like lye) and fatty acids or alcohols (like animal lard or vegetable-based oils). Hand-processed soap is an example of anionic surfactants at work. Other examples of anionic surfactants are sodium sulfates, ammonium sulfates, sulfosuccinates, sarcosines, sarcosinates, isethionates, and taurates.The high foaming, cleansing, and washing properties can lead to skin irritations so depending on your product, you may want to choose another category of surfactants, or balance the anionic surfactants with the addition of amphoteric surfactants.
2. Amphoteric surfactants
Amphoteric surfactants are the most gentle and flexible of the surfactant categories, and can either have a positive or negative charge, depending on the pH or alkalinity of your finished product. Hence the amphi prefix.If you are formulating a product in which the nourishing and conditioning properties are most important, then you may choose an amphoteric surfactant and give the finished product a lower pH. On the other hand, if sudsy and foamy are your goal, create a recipe with a higher pH when using an amphoteric surfactant. With the higher pH, the amphoteric surfactant will work more like an anionic surfactant.When used alone, amphoteric surfactants will give you a gentle cleansing product. Adversely, when an amphoteric surfactant is coupled with an anionic surfactant, the amphoteric surfactant mellows the harshness of the anionic surfactants. In fact, amphoteric surfactants can be used solo and in conjunction with any other of the surfactant groups. Their adaptability is just one of the reasons why they are so widely used.Some examples of well know amphoteric surfactants are coco betaine, lauryl betaine, and hydroxysultaines.
3. Cationic surfactants
Cationic surfactants are the opposite of anionic surfactants. They have a positively charged water-loving head. This positive charge enables cationic surfactants to deliver nourishing benefits to skin, hair, and body, but used alone, do not have high foaming capabilities. These surfactants are often used where foaming isn’t necessary, such as in hair conditioners.Cationic surfactants work well with both amphoteric and nonionic surfactants. However, because of the opposing charge cationic (positive) and anionic (negative) surfactants will not combine.Common cationic surfactants for bath and body formula are the chlorides; benzalkonium, stearalkonium, and centrimonium, and trimethyl ammoniums, and methyl sulfates.
4. Nonionic surfactants
Nonionic surfactants have no foaming capabilities and are rarely used as a recipe’s main surfactant. Unlike anionic surfactants, these surfactants do not have an ionic charge in their water-loving heads.The end result of using a nonionic surfactant is gentle, no-foam cleansing product. No-foam cleansers my need extra marketing messaging to reinforce that the cleanser works even without the foam.Some nonionic surfactants are ethoxylated, meaning they have had some reaction to the addition of ethylene oxide. With this reaction comes an even more water-loving head, almost as if it has been supercharged. This then makes nonionic surfactants like Polysorbate 20 excellent solubilizers. Nonionic surfactants can also be used in formulations to reduce irritants, due to their gentle cleansing ability. And, they are excellent as an emollient, softening and soothing skin. Plus, the nonionic surfactants can stabilize foam in recipes. Nonionic surfactants work wonderfully with every other category of surfactants.Some common nonionic surfactants used in bath and body recipes are polysorbates, emulsifying wax NF, e-wax, glyceryl oleate, glyceryl stearate, and ingredients with the prefix PEG, ceteareths, oleths, sorbitans, lauryl glucoside, and polyglycose.
Natural surfactants are hardworking ingredients to help your cosmetics formulas shine. Whether you’re looking for cleansing, solubility, emulsifying, or conditioning, consider adding one or more surfactant to your recipe.
Glossary of Natural Surfactants
Interested in adding some surfactants to your recipes? Below is a list of some commonly added surfactants to natural cosmetics.
Sodium Lauryl Sulfate (can be derived from coconuts) A strong anionic surfactant used for high foaming action. It is easy to thicken and can cause irritation in higher percentages.
Ammonium Laureth Sulfate (derived from coconuts) A strong anionic surfactant used for high foaming action. Can cause irritation in higher percentages.
Disodium Lauryl Sulfosuccinate (derived from coconuts), A mild anionic surfactant that is gentle on the skin and mildly foaming
Cocoamphocarboxyglycinate (derived from coconuts) A mild, amphoteric surfactant
Decyl Polyglucoside (vegetable derived) used in baby shampoos because of its gentleness
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 Sulfoacetate (much milder surfactant than SLS
Sodium Lauroyl Sarcosinate (derived from vegetables) Is a natural substitution for SLS
Sodium methyl cocoyl taurate (derived from coconut)
Sucrose Cocoate (derived from sugar)
Polysorbate 20 (vegetable derived) nonionic surfactant
Polysorbate 80 (vegetable derived) nonionic surfactant