Coco sounds natural and it is easy to jump to the conclusion that it therefore must be a better choice. Sure, the base ingredient of Sodium Coco-Sulfate is coconut oil, which might even be organically produced. Unfortunately, this is where the likeness with nature ends. Sodium Coco-Sulfate is a very good example of how the beauty industry tries to fool us consumers by inventing new and fancy names for ingredients they are trying to hide.
What is Plant-Derived SLS?
How SLS Is Made?
SLS is made by reducing the fatty acid lauric acid to lauryl alcohol, which is then sulfated with either Sulfur trioxide or Chlorosulfonic acid. The formed lauryl sulfuric acid is thereafter neutralized by Sodium hydroxide or Sodium Carbonate to sodium lauryl sulfate [1].
Sodium lauryl sulfate (SLS) is made by a process where sulfate is attached to a lauryl alcohol [1]. The lauryl alcohol may come from the petroleum industry but might also be purified from cheap plant-oils like coconut oil or palm oil. The final product can then be marketed as plant-derived and appears more natural to the consumers, despite the fact that SLS definitely not is a natural surfactant.
Sodium Coco-Sulfate Is Composed of 50% SLS
Instead of specifically purifying the lauryl alcohol from the coconut oil, sometimes a less pure mixture of fatty acids is used in the process. You then get a mix of surfactants, which is called Sodium Coco-sulfate.
Coconut oil is comprised of 50% lauric acid, 20% myristic acid, 8% palmitic acid, as well as small amounts of both shorter and longer fatty acids [2,3]. This means that once the so-called Sodium Coco-sulfate is produced, it is comprised of 50% Sodium Lauryl Sulfate, 20% Sodium Myristyl Sulfate, 8% Sodium Palmityl Sulfate etc. A mixture of surfactants whose properties not particularly differ from pure SLS, organic or not.
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| C6 | Hexyl |
| C8 | Caprylyl |
| C10 | Decyl |
| C12 | Lauryl |
| C14 | Myristyl |
| C16 | Cetyl |
| C18 | Stearyl |
How irritating a surfactant is for the skin depends partly on the charge of the head and partly on the length of the tail. The longer the tail, the less water-soluble the surfactant and the more difficult to rinse off. The longer a surfactant stays on the skin, the more it irritates. At the same time, the longer the tail, the less likely to pass through the epidermal water-barrier. When a surfactant passes the barrier, it creates holes that results in the loss of moisture and natural moisturizing factors (NMF). Anionic surfactants like sulfates also destroy the stucture of keratin and other skin proteins. Lauryl with its 12 carbons is the most irritating tail length because it is long enough to be difficult to rinse off and at the same time short enough to pass through the epidermal water barrier [4]. The table summarizes the INCI names of the most common surfactant chains found in beauty products. C is the number of carbons. The higher the number, the longer the chain and the less water soluble the surfactant.
References
- Cosmetic Ingredient Review (CIR), Final Report on the Safety Assessment of Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate, December 1, 1983. 2(7): 127-181.
- Laureles, L.R. et al., Variability in Fatty Acid and Triacylglycerol Composition of the Oil of Coconut (Cocos nucifera L.) Hybrids and Their Parentals. Journal of Agricultural and Food Chemistry, 2002. 50(6): 1581-1586.
- Orsavova, J. et al., Fatty Acids Composition of Vegetable Oils and Its Contribution to Dietary Energy Intake and Dependence of Cardiovascular Mortality on Dietary Intake of Fatty Acids. International Journal of Molecular Sciences, 2015. 16(6): 12871-12890.
- Wilhelm, K.P. et al., Surfactant-induced stratum corneum hydration in vivo: prediction of the irritation potential of anionic surfactants. J Invest Dermatol, 1993. 101(3): 310-5.
