All about surfactants and how to choose a mild shampoo


Every shampoo in the market whether it is a normal shampoo or one which claims to be sulfate-free always contain some kind of surfactant. Surfactants are added in the formulation for their cleaning property as they act like a detergent. Their main aim is to remove the dirt, excess sebum and oil from the hair. As we all know, curly hair are already moisture deprived so using the shampoo containing harsh surfactants may lead to the stripping off of natural oils and moisture from our hair that it badly needs.

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Micelles formation

How surfactants act as cleaning agents
A surfactant molecule consists of two parts. The tail part, which is hydrophobic (water fearing) is non-polar and the other part is head, which is hydrophilic and it is polar in nature. This dual nature gives them their cleaning property. At good concentrations in water, surfactant molecules group together to form three-dimensional structures known as “micelles”. These structures are clusters of molecules with an oily center made up of the non-polar tail, surrounded by a shell formed by the polar portion of the molecule. These micelles absorb oils from your skin, hair or clothes, and trap them inside until they are removed from the surface by rinsing with water.

TensideHyrophilHydrophob

Top-bottom: nonionic, anionic, cationic, amphoteric

Types of surfactants
Surfactants are classified based on polarity of their head part. A non-ionic surfactant has no charge groups in its head. If the head carries a negative charge, then it is anionic. If it has positive charge, then it is classified as cationic. If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic or amphoteric.

So, now we know a little bit about the chemistry of surfactants. The question remains, which surfactants are harsh to skin and hair and which ones are milder and hence do not strip off our hair and are less irritating to the skin.

Anionic Surfactant
Most of the shampoos that are available contains one of the below anionic surfactant as their primary surfactant.

Below mentioned sulfates are the harshest anionic surfactant that we should avoid in our products.

Sodium Lauryl Sulfate (or sodium dodecyl sulfate) known as SLS
Sodium Laureth Sulfate or (sodium lauryl ether sulfate) known as SLES
Ammonium Lauryl Sulfate
Ammonium Laureth Sulfate
Sodium Myristyl Sulfate
Sodium Myreth Sulfate
Sodium Coco or Cocoyl Sulfate
Sodium C14-16 Olefin Sulfonate
TEA Lauryl Sulfate
TEA-dodecylbenzenesulfonate
Sodium Alkylbenzene Sulfonate
Ammonium or Sodium Xylenesulfonate

Milder and more gentle anionic surfactant are

Sodium Cocyl Isethionate
Sodium Lauryl Sulfoacetate
Sodium Socoyl (or lauryl/lauroyl) Sarcosinate
Ethyl PEG-15 Cocamine Sulfate
Dioctyl Sodium Sulfosuccinate (Diethylhexyl Sodium Sulfosuccinate)
Sodium Lauryl Glucose Carboxylate
Sodium Methyl Cocoyl or Lauryl Taurate
Sodium Cocoyl Glycinate
Sodium lauroyl/cocoyl glutamate

Cationic Surfactant
As opposed to other classes of surfactants, these positively charged surfactants are used primarily in conditioners. This class of surfactants is well known as a conditioning agent. Our hair is negatively charged. The more the hair is damaged, the more negative charge it carries. So, these positive charged cationic surfactant bond to our negative charged hair and get adsorbed (not absorb) on the hair shaft and provide the conditioning effect.

Most common cationic surfactant are

Cetrimonium chloride
Cetrimonium bromide
Behentrimonium methosulfate
Behentrimonium chloride
Stearalkonium chloride
Stearamidopropyl dimethylamine (lactate, citrate, propionate)
Isostearamidopropyl dimethylamine
Behenamidopropyl dimethylamine

Non-Ionic Surfactant
This type is more gentle than anionic surfactant but does not foam as good as anionic surfactants. These are generally combined with other anionic surfactants to create the milder shampoo.

Non-ionic surfactants are

Decyl glucoside
Laureth- (10, 23, 4)
PEG-10 Sorbitan Laurate
Polysorbate- (20, 21, 40, 60, 61, 65, 80, 81)
Steareth- (2, 10, 15, 20)
Cocamidopropylamine oxide

Amphoteric (or zwitterionic) Surfactant
These surfactants provides mild cleansing and are added with other anionic surfactants to reduce the irritation caused by them. They help to boost the foam formation when combined with other surfactants. These surfactants can not be used alone in the products as these do not provides good cleansing properties so are always to be used as secondary surfactant.

Ampoteric surfactant are

Cocamidopropyl betaine
Coco betaine
Sodium Cocoamphoacetate
Disodium cocoamphodiacetate
Disodium cocoamphodipropionate
Sodium Lauroamphoacetate

shampoo

Tips for buying milder shampoos

  • Avoid using products that contains sulfates and sulfonates.
  • Prefer products having non-ionic and amphoteric surfactants. These surfactants should be listed on the top of the ingredients list after water meaning higher concentration of these are used than any other anionic surfactants mentioned in the ingredients list.
  • Look for products in which only milder anionic surfactants are used.
  • Other conditioning ingredients (like polymers or quaternary agents. Will write a post on conditioning agents later) should be present in the ingredients list to offset the drying effect caused by the shampoo.

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3 thoughts on “All about surfactants and how to choose a mild shampoo

  • Sheethal

    Hi,

    My shampoo contains capryl carylic glucoside, coco glucoside, cocamido propyl betaine, neolen pe, lemon oil, tea tree oil, neem oil potassium sorbate and aloe voera which are either non-ionic surfactant or amphoteric sufactant).
    Will this shampoo be good on curly hair?

    • Asha Barrak Post author

      Yeah Sheetal all of these are mild surfactants, so it meets the first criteria. But you can only say after trying that the shampoo would work on hair and how do you feel it. Also, when you shampoo, mostly concentrate on scalp and let it run down rest of your hair. Do not apply much of shampoo on hair strand if you are using products silicone free.