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Shampoo 101: Surfactants

To some people, washing their hair is just a basic element of their personal hygiene, to others, it’s only the first step in an elaborate hair care routine: But do we really need to assemble half a salon in our showers, like some beauty gurus on youtube seem to suggest? Or is there a happy medium between using plain old soap and spending fortunes on a whole array of shampoos?

In order to answer this question, it might be helpful to go back to basics and reconsider what shampoos are supposed to do in the first place: I think everybody would agree that a good shampoo should give your hair a thorough cleanse without being irritating or drying. But as you might know from personal experience, finding a product that fulfills these quite basic requirements is tricky enough! In the following Hairvember posts, I want to investigate on shampoos and their ingredients in order to help you finding “the one” 🙂

Find a shampoo that gets the job done without being to harsh or stripping

Since shampoos are detergents, the main active ingredient in any basic shampoo is usually a surfactant. Surfactants, or “surface acting agents”, are responsible for the product’s cleansing properties: A surfactant molecule has a hydrophilic or water-loving head an a lipophilic or oil-loving tail. When you wash your hair, the hydrophilic head turns towards the water and the lipophilic end towards whatever dirt is on your hair: To simplify matters, one could say that the soil is “wrapped up” by the lipophilic tail, lifted away from the hair and eventually dispersed in the water.

If you want a thorough cleanse (which is the whole point of washing your hair) and are not ready to switch to fully natural alternatives like rhassoul (or no-poo :)), I am afraid there is no way around surfactants. However, there is a great variety of them, and choosing a shampoo is mainly about choosing which kind of surfactant to rely on.

According to their ionic nature, surfactants can be divided into four categories that differ in their foaming and cleansing properties, but also in harshness or mildness. Don’t be irritated by the fact that I only discuss three types of surfactants in my diagram: For simplicity’s sake, I have skipped the fourth kind, which is not used as a surfactant/detergent in shampoos because of its poor cleansing properties.

(Click on the diagrams for better resolution)

SurfactantsPart1

Each category can be divided in subcategories of non-ionic, amphoteric and anionic surfactants: I have listed the most frequently used ones and their specific properties below:

SurfactantsPart2

As you may be able to derive from this diagram, there isn’t something like the ultimate surfactant: They all have their strengths and weaknesses, and should therefore be combined in a formulation for best results. In the end, it all comes down to finding out what works for you, i.e. to finding the right balance between cleansing and foaming properties on one hand, and mildness on the other.

Even if it is hard to give general recommendations, you might find the diagrams helpful as a guideline:

  • Products containing anionic surfactants are certainly more pleasant to use because their lather feels a lot thicker and more luxurious than the foam of shampoos relying on non-ionic surfactants only. And who doesn’t like a good head full of bubbles, right? 🙂 But keep in mind that the price you have to pay for your bubbly pleasures is a much harsher cleanse.
  • If you’ve got short and very greasy hair, you might well get away with using this kind of surfactants (whether your scalp likes such a treatment is a whole other story!).
  • If your hair is long, dry, or if you plan to grow it, anionic, foamy surfactants are likely to be too stripping for you, and you might consider using milder, non-ionic surfactants.
  • Non-ionic surfactants are also the way to go if you have got a sensitive scalp.
  • Helpful tip: You can improve the cleansing properties of non-ionic surfactants by just letting the shampoo sit on your head for a bit longer before you rinse it out!
  • If you really need your bubbles and cannot get used to non-ionic shampoos, you can reduce the harshness of an anionic formulation by using less product and lathering it up in your hands before you wash your hair. You could even dilute the shampoo in a separate bottle with a bit of water.

I hope you found this little surfactants 101 helpful to decipher the back of your shampoo bottles and find the right product for your hair. Stay tuned for my next Hairvember posts, in which I am going to address other shampoo ingredients, discuss a few frequently heard tips on how to wash your hair, and find out what all the hype around dry shampoos and not washing your hair really is about!

(Thumbnail: Creative Commons bubble and squeaky clean by Lisa Murray used under CC BY 2.0)

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5 thoughts on “Shampoo 101: Surfactants

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