Al asks…Okay, so here’s my question: I look for strong enough surfactants for my hair, that means, I search something that would clean my hair sufficiently but at the same time, I want the damage from my surfactant to be the less possible. There comes cosurfactants, how they work? As far as I know, cocamidopropyl betaine for example may make the formula milder even when there’s a stronger surfactant in it. Therefore my question is, how do corsufactants work in relation with stronger surfactants? How to consider them when searching for milder but functional formulas? Well I hope what I read was right, at least!
The Left Brain responds:
Great question Al but you might be missing the forest for the trees. If you’re most concerned about getting your hair clean without over stripping it then I think just a mild shampoo à la one of the many sulfate free alternatives on the market today should fit the bill for you.
The only time that sulfate free formulas may not provide sufficient cleansing is if you are a very heavy styling product user – particularly hairspray because the resins used to hold hair tend to be fairly water insoluble.
Now, having said all that we’re glad to give you a quick tutorial on co-surfactant.
3 reasons shampoo has multiple cleaning agents
Without going into too much detail. There are really three basic reasons to use a cosurfactant.
The first is to boost foam. Cocamidopropyl betainl for example is an excellent secondary surfactant to use because it helps stabilize and give a richer foam. You wouldn’t get the same effect if you just added more of the primary surfactant.
The second reason is to help control the rheology of the product. Co-surfactants can be more efficient thickeners. Once again using Cocamidopropyl betaine as an example, a little betaine makes the formula more salt responsive so it’s easier to thicken.
Thirdly cosurfactants can help improve the mildness of a detergent formula while controlling cost. Decyl glucoside, for example, is quite mild but can be too expensive to use as a primary surfactants in some formulas. By using it as a secondary surfactant you can improve the overall mildness profile of the formula and keep costs at a manageable level. (see the discussion in our Forum for more details on how cosurfactants reduce irritation.)
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