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Cosurfactants
  • Al

    Hi, brains :D


    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! :P


    Greets!

  • sarahf
    Hi Al,

    I'm not a brain, but my recollection (someone correct me if I'm wrong) is that the brains have indicated that the major differences between the surfactants commonly used in shampoos are in terms of irritant potential for the skin, not damage to the hair.  In other words, I'm not sure you'll get more hair damage by using a stronger surfactant, although you would dry your scalp more and maybe irritate it more.  I suppose it could be argued that overcleansing the scalp and hair could leave the hair less protected by your natural oils, but that is different from damaging your hair.  Okay, I'll stop now--because I may be misinformed...

    Sarah
  • alchemist
    In solution, provided the concentration is high enough, surfactants will form micelles (like little balls) this is call the Critical Micelle Concentration (CMC) .  The simple version of the theory is that while a single surfactant molecule can penetrate the skin and cause irritation, the micelles are too large to penetrate to get through the barrier. Adding a second surfactant (cosurfactant) will decrease the CMC so more of the surfactant is in micelles rather than in free solution so lower irritation occurs.  So it's even possible that two strong surfactants can be put together to make a milder product.

    Choice of cosurfactant(s) can get a bit more complicated as surfactants can be chosen not only to improve mildness but also to change foam aesthetics (did you want big bubbles, lacy bubbles, creamy bubbles? Lots of foam, no foam?) as well as product viscosity.
  • sarahf
    I gues the bottom line is (to summarize the OP's question) can surfactants damage the hair itself (not the skin)?  At least that was how I understood the question.
  • Al

    Thank you both for answering!

    First, thank you, alchemist, I find the thing with surfactants a little bit tricky since there are several things that may be involved as a surfactant in a formula and it's not always as easy to avoid the "strongest" ones when searching mildest products. 


    Sarahf: Well far as I know damaging the hair is rather easy (and quite inexorable!), and using unnecesary strong surfactants dries the hair more than needed therefore long term the hair will be worse compared to when using mildest formulas wich helps to mantain hair's...¿humidity? I mean I think (not know since I'm not sure...I'm never sure with this things, well) it's a goal to mantain nice water levels on the hair, stripping it's oils too much will lead to drier hair therefore I asume it contributes to damaging the hair - faster. More than saying that surfactants by themselves damage the hair, what I assume is that the effect stronger surfactants have when used is more damaging than opting for another options. Having that said, the only thing I've read about surfactants and it's direct effect on hair was about pH levels and protein lose, and even the common used strong surfactants were "safe" to use. I don't know if there may be other ways for the surfactants to damage the hair, though. In my case also there's sensitive skin in the middle. 


    My question was targeted to learn a bit about cosurfactants since it's not easy nor cheap for me to find no-sulfates shampoo, it's a lot easier finding products with cosurfactants on them in the super, and in general the more you know the best decision you make, so well :)

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