Sulfate-free surfactant
- Also known as
- sulfate-free, SLS, SLES, sodium lauryl sulfate, sodium laureth sulfate
A sulfate-free surfactant system is one formulated without sulfate surfactants such as sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES), usually in pursuit of milder products or to avoid ethoxylated ingredients. Sulfate-free is a marketing description, not a regulated term.
What does sulfate-free mean?
Sulfates here means sulfate surfactants, chiefly sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). They are inexpensive, effective anionic surfactants that clean and foam strongly, and they have been used for decades in shampoos, body washes, toothpastes and cleaners. A sulfate-free product is formulated without them.
Why formulators go sulfate-free
- Mildness. SLS in particular can irritate skin and eyes at higher concentrations, and some consumers and brands prefer gentler products.
- Avoiding ethoxylated ingredients. SLES is made by ethoxylation, which can leave trace 1,4-dioxane.
- Consumer preference, including claims for color-treated hair and sensitive skin.
Common sulfate-free surfactants
- Sulfonates, such as olefin sulfonates, which are anionic but not sulfates.
- Isethionates, taurates and sarcosinates, milder anionic surfactants.
- Glucosides, such as alkyl polyglucosides, which are nonionic.
- Amphoteric surfactants, such as betaines.
- Biosurfactants, such as sophorolipids.
Trade-offs
Sulfate-free systems often cost more, may foam less, and can be harder to thicken, so they usually rely on blends of several surfactants. Because “sulfate-free” is not a regulated claim, it says what a product leaves out, not how it performs or how mild it is.
Frequently asked questions
SLES is made by ethoxylating the fatty alcohol before sulfating it. The ethylene oxide units make SLES generally milder than SLS, but ethoxylation can leave trace 1,4-dioxane.
Not necessarily. Mildness depends on the whole formulation, including which surfactants replace the sulfates and at what concentrations.
Sources
- Surfactants and Interfacial Phenomena, 4th edition, M. J. Rosen and J. T. Kunjappu, Wiley, 2012
- Cosmetic ingredient safety assessments, Cosmetic Ingredient Review