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Why use stearic acid?
It’s one of those ingredients I don’t quite get, to thicken the formula? Are there any skin benefits? Enhance emulsion stability?
Why not just use e.g. cetyl alcohol instead?
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9 Replies
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sensorials. Gives a ‘cold’ effect, e.g. Nivea “Cold Cream”.
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But it doesn’t actually have any positive effects beyond that?
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I suppose I am guilty of putting stuff in because it seems to be what everyone else puts in.
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Stearic acid is also an occlusive agent, though not as effective as, say, petrolatum.
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It’s an emulsifier really. Typically, you use it and then neutralize it to create an emulsion.
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@Belassi I like your logic the best
Actually @Zink is right in asking why stearic acid and why not cetyl alcohol. But it’s really matter of choice and the kind of formula you are looking to develop, it’s a wholesome thing you consider. Sometimes it fits the scheme and at times you can replace it, just a loud thought. -
There’s something to be said for using it just because it’s convenient, too. It has it’s widest use as an emulsifier when it’s neutralized - but, if you’re already using it as an emulsifier, sometimes it’s just easier to also use it as a viscosifier/bodying agent instead of going through the somewhat involved process of bringing in a new material and/or supplier.
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Unilever has been using stearic acid for a different purpose: replenishing the stearic acid that is highly removed during by surfactants:
Since their cleansers has a pH around 7, the stearic acid that can be found in their products isn’t necessarily saponificated. -
Looks like I’m not the first to ask this questons:
http://swiftcraftymonkey.blogspot.com/2009/07/cetyl-alcohol-vs-stearic-acid.html
Seems like the only conclusion I can find is that stearic acid creates a lotion with more drag, good for e.g. foot creams, wheareas cetyl alcohol provides more glide.
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