Ingredients Dictionary: Cetyl Alcohol, Stearyl Alcohol, Cetostearyl Alcohol

Today's ingredient is one which everyone asks about. It is a main (even ubiquitous) ingredient in conditioner but is not really one that people rave about.



I have combined these three alcohols with good reason...........read on! (I  sometimes refer to cetyl alcohol alone for simplicity but all the information here applies to all three!)

CETYL ALCOHOL, STEARYL ALCOHOL AND CETOSTEARYL ALCOHOL
Property	Notes
What is it?	A fatty alcohol ( meaning it is an alcohol which comes from fat). It does not behave like a 'real alcohol' for example ethanol or propanol .
Where is it derived from?	Commonly coconut oil and palm oil
How is it made?	Cetyl alcohol is made by heating coconut oil with a strong base (for example lye - sodium hydroxide). This process is the same process used to make soap (saponification)
What is the difference between cetyl, stearyl and cetostearyl alcohol	Cetyl and Stearyl alcohol are very similar. Stearyl alcohol is a slightly longer version of cetyl alcohol having two additional carbons (i.e Cetyl has 16 carbons while Stearyl has 18). Cetostearyl alcohol is simply a combination of cetyl and stearyl alcohol (did you guess from the name?).
Where will you find fatty alcohols in hair products?	Hair conditioners (both rinse out and leave in).
ACTION IN HAIR CONDITIONER
What do fatty alcohols do in hair conditioner?	Hair conditioner is a mix of water and oils. However oils and water do not mix...........unless you add a surfactant to them. When oil and water are mixed,  the resulting solution is known as an emulsion. Therefore you will commonly hear cetyl alcohol and the rest of the fatty alcohols being referred to as emulsifiers (i.e the things that help oil and water to mix)
How much cetyl alcohol is added to conditioner.	Typically between 2 and 4% (can be lower or high)
Is cetyl alcohol a major component of hair conditioner?	Yes for rinse out and deep treatments. It will normally appear within the first 5 ingredients after water.It is responsible for the creamy look of conditioners.
ACTION ON HAIR
So does cetyl alcohol really do anything to hair itself?	Yes it has some effect on hair. During conditioning, cetyl alcohol is responsible for allowing conditioner to spread easily over the hair. Without it, the conditioner would probably separate out in the bottle (into water and oil) and on hair would be difficult to spread. Once rinsed off, some cetyl alcohol is thought to deposit on the surface of hair (i.e cuticle). This will create a feeling of softness (hair may not be soft but feels soft!).
Since it is a surfactant can it wash hair?	Not really. It is large and non ionic (meaning it does not have a charge when placed in water). Small charged surfactants tend to be the best for oil removal (i.e shampooing)
Does cetyl alcohol penetrate hair	There are no published studies to indicate that it does. It is unlikely that it would as it is large (things that normally penetrate undamaged hair are 3-4 carbons in length - cetyl alcohol is a massive 16 carbons).
Is cetyl alcohol a major component of hair conditioner?	Yes it is for rinse out and deep treatments. It will normally appear within the first 5 ingredients after water. Creamy leave ins may or may not have cetyl alcohol as a major components.

Sources for this article:

1. J Cosmet Sci, pp 37-56, 2006

2. Int J Cosmet Sci, pp 47-59, 2004.



Any Questions?