Demystifying Sulfate-Free Cleansing Formulations
The beauty industry is ever-changing, and the world is turning away from using the once-common Sulfate surfactant ingredients, SLS (sodium lauryl sulfate) and SLES (sodium laureth sulfate).
Numerous concerns are associated with using sulfate surfactants in shampoo, shower gel, and other cosmetics products. Evidence suggests that they can cause eye and skin irritation with long-term use. This poses health concerns and, since many products containing these ingredients are tested on animals, also presents ethical concerns.
As the downsides of SLS and SLES come to be more widely understood, there are new challenges that need to be addressed. As more and more consumers turn to sulfate-free products, brands are scrambling to find an alternative ingredient that can thicken their formulas effectively without sacrificing clarity.
We hope that the following Q&A will help address some common questions manufacturers face when they begin developing these types of sulfate-free cleansers.
What Is a Surfactant?
A surfactant, or surface-active agent, is a chemical that helps lower the surface tension of water, allowing the liquid to soak more easily into other substances. If the head of the surfactant molecule is hydrophilic (water-loving) and the tail is hydrophobic (water-repelling), it will form small balls called micelles when mixed with water.
If you mix oil, water, and surfactant ingredients, the oil will reside inside these micelles, making it easier to wash away with water.
In the context of hair products such as shampoo, a surfactant allows water to better penetrate the oils in your hair, which allows dirt to be rinsed off more easily.
Are All Surfactants Sulfates?
People often ask us, “Are a surfactant and a sulfate the same thing?” In a word, no.
The most common surfactant formulations, such as SLS and SLES, contain sulfates. However, the two terms are not synonymous, and sulfate-free surfactants formulations are becoming increasingly available and more widely used within the cosmetics industry.
What is Sulfate-Free?
A sulfate-free product does not contain SLS, SLES, or any other sulfate ingredient. Other ingredients will be used in place of sulfates to achieve the same cleansing effects.
According to Digital Journal, the global market for sulfate-free shampoo was worth $4.16 billion in 2021 and is expected to grow this year and beyond.
Is SLS-Free the Same as Sulfate-Free?
No. SLS is one of the most common sulfate-based surfactants, but it is not the only one. Consumers should always check the ingredients list or look for products marked as “sulfate-free”, not just “SLS-free”, and manufacturers must ensure their formulations are correctly labeled.
Are All Sulfate-Free Surfactants Easy to Thicken?
Certain sulfate-free surfactants are easier to thicken than others. For example, Alpha Olefin Sulfonate is one of the more economical sulfate-free surfactant formulations and is relatively easy to thicken.
On the other hand, glutamate-based surfactants (that is, those derived from amino acids) are known for their mildness and pleasing sensory properties but are exceedingly difficult to thicken in a stable formula.
What Happens When You Mix Different Surfactants Together?
In chemistry terms, when you mix primary surfactants with co-surfactants, you change the average surfactant head area, which influences how the micelles are structured. By combining primary surfactants with co-surfactants, formulators are able to adjust the performance of their finished product.
Additionally, mixing different types of sulfate-free surfactant formulations can enhance cleansing, foaming, and sensory properties, but this makes them more challenging to thicken.
So How Do Formulators Thicken These Types of Formulations?
Formulators achieve this by changing the shape of the micelles. There are three principal ways to shape the micelles:
- First, you can change the shape from spherical to longer and thinner using a co-surfactant like Cocamidopropyl Betaine.
- Second, you can change it by adding more salt and, potentially, by combining that with co-surfactants.
- Third, you can add more Hydrophobic Non-Ionic Surfactant thickeners like Glyceryl Laurate or Laureth-2.
These steps will all help make the micelles’ shape less round and curved, making the formulation easier to thicken. However, the three approaches above are generally more effective for sulfated surfactants. For sulfate-free cleansing products, the classical methods are often insufficient to achieve the desired viscosity or clarity.
Therefore, a different class of ingredients known as non-ionic associative thickeners—such as our Sorbithix L-100—begins to play an essential role in thickening. Unlike other thickeners, Sorbithix has a unique star polymer shape designed to connect with surfactant heads and tails, making it easy to form a large, linked network of micelles that boosts viscosity and stability.
Where to Learn More
If you're new or unfamiliar with this type of formulation, we hope these tips will help guide your path to success.
As a trusted surfactant thickener supplier and surfactant-related specialty ingredients sourcing specialist, we would be delighted to answer any questions you may have. Please feel free to reach out to us if you have additional queries, and you can always find more information about Sorbithix L-100 or any other Applechem products at Applechem.com.