Tuesday, 8 June 2010

Alternatives to sulfate shampoos: Cocamidopropyl betaine


A commonly proposed alternative to SLS (top image) in shampoo is cocamidopropyl betaine (bottom image).

A key reason why cocamidopropyl betaine is used is because it is less irritating. However the reduction in irritancy does come at a price, a reduction in efficacy.

How and Why is cocamidopropyl betaine less effective?

Remember that both SLS and cocamidopropyl betaine are both surfactants. Their role is to form micelles which help to dissolve oil from hair (jog your memory with this post). You really must understand what micelles are before you go any further so I will suggest again that you really must read this post (Really, yes I linked it twice, and here it is again :) this post).

If you have a look at the chemical structures above, you may notice that the long zig zag portion of the SLS is shorter than that of the cocamidopropyl betaine. This little zig zag portion is the tail part of the surfactant (orange in the diagram below). A shorter tail allows the micelle to form easily while a longer tail, not so much!


Therefore since cocamidopropyl betaine is not as effective at forming micelles, it is therefore not as effective at dissolving oil and therefore not a particularly strong cleanser.

Does this mean that cocamidopropyl betaine is not good?

No, it means that cocamidopropyl betaine is just milder (Journal of Surfactants and Detergents, pp 235-239, 1998) leaving some of the oil layer undisturbed (not necessarily a bad thing for dry hair) and not necessarily removing all build up.

How can the cleaning power of cocamidopropyl betaine be improved?

Commonly you will find it along with other surfactants. It can also be added (and usually is) to SLS containing shampoos to reduce irritancy. A very common shampoo combination is SLS, SLES and cocamidopropyl betaine which produces a suitably cleansing and low irritation formula.

Is cocamidopropyl betaine irritating?

It is known widely as very mildly irritating, much much much less than SLS. However, there are some people, as always, who will be very sensitive to it ( Dermatitis, pp157-60, 2008). Additionally poor manufacturing can lead to inclusion of by products that are irritating. However on the grand scale as I said before, cocamidopropyl betaine is significantly less irritating than SLS.

Next up: Alternatives to sulfate shampoo: Castile Soap!

11 comments:

  1. Awesome. Thanks!

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  2. would this be enough to cleanse if you co- washed and didn't use silicones (except water soluble ones) but say used polyquats? ty CHM

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  3. Hi Jc: So is it possible that a shampoo claiming to be a "clarifying" shampoo that has cocamidopropyl betaine as a main ingredient is NOT honestly clarifying the hair?

    What are your thoughts on mixing this type of shampoo with a small amount of an SLS shampoo?

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  4. CHM - polyquats similar to silicones tend to require SLS for removal. However this depends on how much is in the product and also some polyquats are 'easier' to remove than others. The best advice I can give is a watch and see approach. If you start experiencing build up then you know perhaps the shampoo is not good enough.

    Calla Lily - Not having actually tested the shampoo, I cannot say definitely. However my instict is that if the shampoo has cocamidopropyl betaine only then it is not really clarifying in the sense of complete oil removal. It may still produce a desirable result but it would definitely not be what I would think of as clarifying.

    If the shampoo has cocamidopropyl and other surfactants as well in the top five, it might be better.

    I think you could mix it with another shampoo (perhaps not directly mix them because they each have preservative concentrations, but perhaps mix a little from each during the wash).

    However my preference would be to find a shampoo that works for you with a ready made formulation that has been tested.

    I guess the question curlies need to ask is do you really want to clarify or do you just want to remove a little bit of the oil?

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  5. Thanks JC - I appreciate you answering my questions about this ingredient! I've been experimenting w/ several sulfate-free shampoos that include this ingredient and I must say I'm impressed so far...they manage to clean my scalp/hair very well without stripping it ... I also try stay away from heavy silicones which probably has something to do w/ the effectiveness of the shampoos that I have been using :)

    Can't wait to see what your research brings out about Castile Soap - KimmayTube (from YouTube) recently posted videos about the extremely high pH (9-10)level of these soaps, even when heavily diluted....however there are so many people who have success using it so I'm curious!

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  6. JC I know I'm a little late with this question but is there a such thing as a sulfate-free shampoo that can actually remove build up? On the rare occasions when I do need to clarify-- like after using cones for heat protection, is SLS my only option to really remove them and then I'll just have to suck it up and deal with the irritation for a few days after?

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  7. Thank you for this article!

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  8. HI there JC :-)

    What a superb site, I only discovered it by chance last night around 8pm UK time and I'm already hooked - THANK YOU!

    I am in the midst of a epihanic (spelling?) hair journey and I'm loveing the fact that your site combines science and VALUE, something i feel I've struggled to find elsewhere 9so far) exc. the Beauty Brains site.

    I have a question I'd love you to consider if possible...which I have searched your site for but so far can't find - apologies if the answer is already here.

    Q) Is it really necessary to use a shampoo that partners your conditioner, i.e Herbal Essences Hello Hydration shampoo with it's accompanying conditioner? The reason I ask is that I'm returning to silicone/shop bought 'standard' products after several years of paying through the nose for all natural products containing minimal ingredients as I feel I no longer believe their claims or quite simply can justify the price! However I have found as a lady with long, red wavy hair (fine in texture, just lots of it) that I seem to benefit from shampoos without SLS etc, my scalp and wavy curls especially.

    Just wondering if using a baby shampoo will be enough to rid my hair of potential build up brought on by my relished return silicones etc. via HE HH!

    Sorry for the length of my first post, promise to keep subsequent ones shorter! I've a feeling your response could be 'suck it and see!' I just wondered what the science behind it would be first :-)

    Hay x

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  9. I heard that cocamidopropyl betaine helps to wash away silicones. According to your posts, I'm guessing that that is false...?

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  10. This may be somewhat out or your area of expertize but I will ask your advice nontheless: I am a serious giant soap bubble enthusiast (bubbles with up to a 6 ft. diameter). I am attempting to create a dry surfactant system as an alternative to Dawn Dish Detergent. My question is this: with your knowledge and background do you think a combined system of SLS/SLSA as my primary and secondary surfactants is so very far off the mark? Best, Rick (Burbrujo).

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    1. Yes that is out ouf my domain Rick! All the best with your research

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