Wednesday, March 2, 2011

What's in Shampoo - About Surfactants

This is part 2 of a mini-series of shampoo, body wash and soap products articles. Read the first part here, or jump straight into the technical stuff. Shampoo (and other soapy, lathery products) work as they do because of surfactants.

Surfactant - What's in a Name
The name surfactant is a compound of 3 words: surface + active + agent. Just as the name is a compound, a surfactant is a sum of several parts. Surfactants have versatile uses and properties – one is the ability to bind oil and water (act as an emulsifier). Other abilities include wetting, dispersing, anti-foaming and – what we all want in our shampoo – foaming. Some surfactants are negatively charged, some positively charged, some swing both ways (just to make things fun) and some are neutral. 

What About Shampoo?
Surfactants are used in a multitude of different ways, but for making shampoo (and body wash), there are 4 main categories involved. Because no surfactant can quite do the job on its own, it's necessary to group them in order to create a shampoo. It's kind of like getting a group of musicians together – each one plays a vital part in the final composition.

Anionic, Cationic, Amphoteric and Non-ionic
Meet The Fab Four
Anionic:  Anionic surfactants are great at foaming but can be irritating for the skin. Anionic means negatively charged.

Cationic: Cationic surfactants will reduce the foaming action of a mix, but they are forgiven for this because their function is to be conditioning. Cationic means positively charged.

Amphoteric: Amphoteric surfactants bring mildness to a mix, but have much less foaming ability than their anionic counterparts. They are therefore usually combined with anionic surfactants. Amphoteric surfactants can be either positively or negatively charged – depending on the pH of the mixture.

Non-ionic: Non-ionic surfactants are quite useful as emulsifiers. Their addition to a mixture will give it body and keep everything from separating, but will also tend to cause a reduction in foaming action. Non-ionic surfactants are neutral.

This is Just the Headlines
Within each of these categories there are numerous surfactants to choose from. (For example, the controversial SLS's are anionic). It is not unusual to see a more than one surfactant from the same category in a shampoo – they counterbalance and/or enhance each others properties depending on what the shampoo is expected to do (cleanse baby's hair, help battle dandruff etc etc). Combined properly, the right mix of surfactants make up the base of the perfect shampoo (or body wash) that does everything you expect it to do and has you singing in the shower. 

Next installment, I'll get into (some) details about some of the surfactants I work with in my products as well as taking a look at some of the ones I won't use. Stay tuned!


kt679 said...

Lise - what are some of the common names for surfactants we might see on a shampoo bottle? Are any of them bad for the environment or our skin? Maybe when you list the ones you personally work with you could let us know if there are ones to avoid? Thank you! Great info!

Lise M Andersen said...

HI Katie,
It's all coming up in the next installment.. promise!


Anette said...

Kære Lise, det er nok mig, der ikke kan se ordentligt, men jeg kan ikke finde din holdning om silikone og sulfater i håret under dine shampooindlæg. Kan du hjælpe?

Lise M Andersen said...

Hej Anette,

Du ser helt rigtig. Jeg har det først med i kommende indlæg hvor jeg går enkelte surfactants igennem en for en. Jeg havde lagt en reminder til mig selv at maile dig nu på fredag - der kommer nemlig en surfactant guide. Mht silikoner - det kommer senere endnu. Sorry at det tager så lang tid, men ellers bliver indlæggene så lange at folk falder i søvn inden de er færdige med at læse! :)