Cocamidopropyl betaine is a bit of a mouthful, but that doesn’t stop it from being one of the most widely used ingredients in shampoos and foam baths. Wikipedia is a good source of information on cosmetic ingredients as a rule, but the entry on CAPB is a bit opaque and was clearly written by someone who knew their chemistry but probably hadn’t had much to do with this widely used material. In particular, he missed the main thing that motivates people to us it, which is bubbles.
People love bubbles. I love bubbles. It is perfectly possible to come up with a liquid that washes your hair perfectly adequately and which doesn’t create bubbles. But where would the fun be in that. And nobody would buy it. CAPB doesn’t create the bubbles but it stabilises them. If it did nothing else, that would be enough to earn its ticket. But it has another trick up its sleeve.
CAPB is relatively mild, but anything with a cleansing action can damage the skin. Nobody has yet worked out a way of removing dirt and grime without also removing some of the skins protective oils at the same time. But by blending a couple of different ingredients you can come up with some formulations that are pretty close to that ideal. Interestingly, how irritating the individual components is doesn’t really give you much idea of how a blend will behave. The most commonly used blend is CAPB, sodium laureth sulphate and cocamide DEA. You see this time and time again because it works so well. It is also a pretty non-irritating blend.
When I first started working in cosmetic formulation in the early eighties it used to be normal to have different products for salon use. So a salon shampoo would have much higher levels of detergent than a simple consumer one. The idea was that a shampoo at a hairdressers needed to be a rather more special event than just washing your hair. This all made sense but it did mean that the people working in the salons tended to get exposed to rather a lot of detergent. The occupational health practitioners picked up on this and tended to pick on CAPB as the main culprit – logically enough as it tended to be in nearly all the formulations. Since then the tendency has been for detergent levels in consumer shampoos to increase towards the levels that used to be regarded as appropriate to salon use. This has partly been marketing driven – marketers like putting the word ‘salon’ on their bottles. It is also bubbleophilia in action again. Given the choice buyers go for bubbles.
But on the whole irritancy is not a problem for most people most of the time. We have all worked out our own routines which have become habits. It is worth bearing in mind that if for any reason you do decide to increase the amount of shampoo you use that there may be a level that starts to affect your skin. It will also degrease your hair shaft making it more brittle and possibly damage the surface of the hair making it less glossy and harder to manage. The nature of the chemistry is such that it is the blend that is having these effects not the particular ingredients, so there isn’t much to be learnt by studying the ingredient list. And if you do have a bad experience with a particular product lowering your use level might be just as effective as changing brands.
On the whole CAPB is a fun ingredient. It helps to make our hair washing and bathing experiences that much more enjoyable. And when we have finished with it is highly biodegradable so you don’t even need to feel guilty about it. Harmless fun for everyone.