Tuesday, 13 August 2013

What separates a great shampoo from a poo shampoo?

While some shampoos can leave our hair squeaky clean these same shampoos can also strip our hair of all moisture - a big no-no for already dry afro hair. A good shampoo merely cleans whereas a great shampoo cleans, retains moisture and prepares your hair for the next step: conditioner. So what’s in a great shampoo, I’ll explain below!

Over time hair becomes dirty and smelly due to our old friend sebum. Sebum is great at lubricating and nourishing the strand but attracts absolutely everything it comes into contact with: perfumes, smoke, dirt particles, sweat and man other yucky things. All this and more is trapped on your scalp. The basic function of a shampoo is to break down the smelly sebum and stop it from reattaching to the strand during washing and this is done by surfactants. Surfactants are small particles that weaken the bond between your dirt and the hair, allowing your fingers to rub off the dirt and there are three types: anionic, amphoteric and non-ionic. During the rinsing stage the surfactants also prevent the dirt from reattaching to the strand and voila… clean, fresh hair! 

Anionic surfactants have an overall negative charge and are the harshest type of surfactant. The original anionic surfactant was just plain ol’ soap, which actually isn’t that great for hair! Soap causes skin and hair damage by causing an increase in pH and by causing the calcium found in hard water to be deposited onto the scalp. These two things result in dry, brittle hair.  Synthetic anionic surfactants were developed to solve these two problems and include anything ending in: 
  • Sulfate
  • Sulfonate
  • Isethionate
  • Sulfosuccinate
  • Sarcosinate
These synthetic ones are still pretty harsh, but they’re cheap, cheap, cheap! Why is that bad news? It means big companies tend to use them the most so any shampoo/soap product you have in your house most likely contains mostly anionic surfactants. Even worse, the two most common anionic surfactants: sodium lauryl sulfate and sodium laureth sulfate, are designed to work in hard water (like the water here in London) so strip away all the sebum on your scalp and hair leaving it dry and unprotected. As I’ve said before, sebum stays on the scalp and upper parts of the afro hair strand so the lower (and older!) parts of curly/coily/kinky hair have no sebum to wash away, instead they become damaged by the harsh detergent. Imagine someone who washes their clean hands over and over again, eventually their hands become super dry and the soap causes the skin to break. That’s what happens to your hair! 

On top of all that (!) your hair needs sebum for protection and lubrication, so when you wash it all away your hair is left open to damage until your scalp produces more. Even conditioners, which are meant to ‘replace’ the lost sebum post-shampoo are only synthetic sebum mock-ups, so it’s best to leave some sebum behind when washing. 

Amphoteric shampoos contain both negative and positive groups on the end of their chains. They are the betaines, sultaines and imadizinolium (aka Miranols) derivatives and are much more milder than the anionics. Usually they are combined with the anionics and stop them from adhering to (and therefore cleaning) the strand as strongly.  

Non-ionic components are the mildest cleansing surfactants and aren’t usually used as they don’t foam as well as the others. In actual fact these types of surfactants are very good at breaking down oils, proving that a cleanser doesn’t have to lather for your hair to be clean. Non-ionic surfactants include polyoxylethylene, polyglycerol and ethanolamides.

So when looking for a shampoo, what you want are more of the amphoteric and non-ionic surfactants rather than the anionics. It’s unlikely that you’ll find a shampoo without any anionic products but you want the betaines and sultaines to at least be in the top 5 (and because ingredients are listed from most to least the amphoteric ingredients should probably be listed before the anionic ingredients).

Next time, I’ll tell you about the most important step of hair washing – conditioners! 

Information from:
Bouillon, C (1988) Shampoos and Hair Conditioners. Clinics in Dermatology, Volume 6, Number 3, pp. 83-92
Gray, J. (2001) Hair Care and Hair Care Products. Clinics in Dermatology, Volume 19, pp. 227-236

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