surfactant + cleanser 101
Finding your go to cleanser or shampoo may be the best thing you can do for your skin or hair routine. It all starts with the surfactant lying in your cleansing products to give your skin and hair a blank canvas after everything it's gone through during the day.
Types of Surfactants
Cationic - positively charged head group
Non-ionic - no charge head group
Anionic - negatively charged head group
Amphoteric - simultaneously carries both anionic and cationic hydrophilic head group
Examples of Common Surfactants & What You Should Know
Sodium Lauryl Sulfate (SLS): an anionic surfactant that has high foam & cleansing properties. It is generally very cheap & easy to source, which makes it a popular choice to use as a surfactant. It has been shown to cause irritation and may not be the best choice for people with sensitive skin or scalps. However, with proper formulation and combining this surfactant with other surfactants, potential irritation can be reduced. Meaning, there shouldn’t be a huge fuss on “sulfate-free”.
Sodium Laureth Sulfate (SLES): is the ethoxylated version of SLS, so it's SLS but with a few more oxygens inserted. It's considered more mild than SLS because of the ethoxylation -- it's more water soluble, and therefore, more mild & less irritating. Ethoxylation is another story though.
SODIUM versus AMMONIUM Lauryl/Laureth Sulfate?: The cleansing portion of the surfactant is the Lauryl/Laureth Sulfate part and not the sodium or ammonium part. Those are just the ions making the charged head group of the surfactant. If you come across a product that markets itself to be SL(E)S free, make sure you check the ingredients list because they might be using AL(E)S instead. They think they're slick, but you are a Cosmetic Padacts blog reader, and you are smarter than them! Remember: sulfates are not that bad when formulated properly, so don’t fall for “sulfate-free” gimmick unless you have an allergy, sensitivity or maybe colored hair. You are a Cosmetic Padacts blog reader!
Fatty Acids + Base: The saponification of fatty acids + base typically yield a higher pH, so if you have dry or sensitive skin, I would not recommend using a cleanser with this combination. However, this combination can yield great foam and cleansing properties. Saponification has been done for many decades and is something that you'll briefly learn about in science class.
Fatty Acid examples: stearic acid, Palmitic Acid, myristic acid
Base examples: potassium hydroxide, sodium hydroxide, triethanolamine
Cocamidopropyl Betaine: an amphoteric surfactant that has excellent foaming, cleansing properties, and stability. It is typically used as a co-surfactant & can decrease the irritation level of anionic surfactants on the skin (like SLS). It can also be sourced from coconuts 🥥.
Sodium C14-16 Olefin Sulfonate: an anionic surfactant that is typically used in sulfate-free cleansing products. It is mild, offers high foam, and has excellent cleansing properties. It is a little more expensive than sulfate-based surfactants but is definitely still on the cheaper side of surfactants.
Sodium Cocoyl Isethionate: one of my favorite sulfate-free surfactants -- an anionic surfactant made from the fatty acid of coconut oil 🥥 . It has excellent moisturizing properties and is mild to use in comparison to more irritating surfactants. It is typically seen in combination with other surfactants, foam boosters, or viscosity increasing agents to meet the aesthetic that consumers are looking for.
(Di)Sodium Cocoyl Glutamate: one of my favorite "natural" & mild surfactants that I look for in cleansing products. It is typically used in combination with other surfactants for foam and product viscosity but can also offer great foam on its own. However, it may be difficult to formulate with due to reduced solubility in water -- just the typical issues you can come across when formulating sulfate-free products.
Why are most surfactants in my cleansing products anionic?
Cationic surfactants adsorb strongly to negatively charged surfaces; therefore, they are not efficiently removed when rinsing. Anionic surfactants typically have great foam and consumers link foam to how efficacious a product can cleanse. Also, think about how like dissolves like -- negative charge with negative charge will result in better rinsing.
The issue that arises is irritation with anionic surfactants. As with all surfactants, there will be some form of irritation because you are removing oil and sebum (excess or non-excess). This can be combatted with the combination of anionic surfactants with amphoteric or non-ionic surfactants or the addition of conditioning and moisturizing agents.
What do I look for in a shampoo or cleanser?
You should know by now that I am an ingredients list reader. I will stand in the aisle and read the ingredients list before I decide to buy a product. Whether it's a cleanser or a shampoo, I always look for conditioning or moisturizing agents that will offset any possible irritation. Therefore, I don't mind using cleansing products with sulfate surfactants, so long as it has ingredients that will condition or moisturize my skin and hair.
Shampoo
For shampoos, I do lean towards sulfate-free surfactant shampoos because it is more mild on my scalp & hair. I also look for shampoos with polyquaterniums & anything hydrolyzed -- like hydrolyzed keratin or protein.
Polyquaterniums are cationic polymers that act as conditioning agents. They'll help in combability of hair and add gloss & shine.
Hydrolyzed keratin or protein will moisturize & strengthen your hair through penetration of your hair cuticle.
(Refer to Science of Beauty -- The Basics: Science of Hair for a refresher on hair chemistry).
Not only am I looking for a nice wash for my hair, I'm looking to repair and strengthen my hair because I honestly do not take care of my hair as much as I should -- guilty. If I can't find a sulfate-free shampoo, I'm fine as long as it has ingredients that will help with irritation.
Facial Cleanser
For facial cleansers, I usually don't experience any irritation when using sulfate-based surfactants or the saponification of fatty acids + base, so I'm typically open to trying new cleansers if my favorite cleanser is unavailable. However, most of the cleansers that I own are all sulfate-free & use a combination of different surfactants.
I typically look for neat and innovative or convenient components when I'm looking to buy a facial cleanser. Following that, I look for conditioning or moisturizing agents -- e.g. humectants, oils, extracts, amino acids, etc. to try and combat any possible irritation that may occur with use.
If you’re interested in pH, there are some Korean brands that showcase the pH or pH range of their product as a part of their marketing story.
Conclusion
Don’t freak out if you see sulfates in your cleansing products. Only steer from it if you absolutely feel the need to, such as allergies or known sensitivities and irritation.
A well formulated cleansing product should not completely strip you and make you feel dry or tight. If you have concerns, look for hydrating or moisturizing ingredients or choose a cleanser that is more creamy in texture.