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Do you need special shampoo after straightening hair?

Al asks…I’ve always read that once you have gone for some type of permanent straightening (like Brazilian or keratin one…) you should not use either salt (Sodium Chloride) or sulfates. If I’m right those process change covalent bridges in the hair so, how do sulfates or salt affect then? I’m also curious if per example sulfates (or salt?) would affect when you’ve done some type of non-permanente straightening, since their lasting power seems to be related to washing frequency. The commercial explanations are that both “wear off” the keratin used to “stuff” the hair – but since is not the keratin the one giving the effect…(or is it?) Also I would like to know how semi-permanent treatments involving some type of chemistry -not only heat- come off, if the products used affect most likely free cysteine and create some type of weak bonds, those “wear off”?

The Beauty Brains respond:
Great questions, Al!

How do chemical hair straighteners work?

As we’ve previously discussed these straighteners work by reacting with the protein bonds in hair that give it structure. As you suggested they do NOT work by stuffing the hair full of keratin.

If you think of the structure of hair as a ladder these protein bonds are like the rungs that cross link the two sides of the ladder. When all the rungs are in place the ladder holds its shape tightly and when the rungs are broken the ladder becomes wobbly and changes shape. Hair is kind of the same way. If you break and reform these protein bonds you can make hair curly or straight.

How do these treatments wear off?

The new bonds formed by these treatments are not as strong or as numerous as hair’s natural bonds so it’s normal that the hair will revert to its normal shape over time. (And of course any new hair growth will be curly.)

How much reversion you see depends on which straightening technology you use:

  • Relaxing is the most powerful and the most damaging but it’s the longest lasting.
  • Formaldehyde straightening is also very effective and long lasting but exposure to high levels of formaldehyde is dangerous.
  • Cysteine based products (like Garnier’s straightening kit) are safer to use and milder on your hair but the bonds they form are not as strong or long lasting.

Do you need a special shampoo?

The idea that you need to use a special shampoo after a hair straightening process is more marketing hype than anything else. There’s no evidence that suggests the type of surfactant impacts how the disulfide bonds oxidize. It’s more likely that the company is trying to sell you a more expensive sulfate free shampoo. Ditto for salt – not only does it not affect the bonds but it’s likely to be present in the formula even if it doesn’t appear on the ingredient list. That’s because salt (we’re talking about sodium chloride here) is a common by-product in the manufacture of many surfactants.

However it IS true that you should wait a day or two before shampooing your hair after a thio or cysteine based straightening treatment because it takes a that long for the oxygen in the air to oxidize the protein bonds.

{ 3 comments… add one }

  • Rozy December 7, 2013, 12:35 pm

    Once I heard the term “special shampoo” my bullshit detectors went off. Definitely marketing. Great response brains!

  • Pedro December 8, 2013, 9:01 pm

    In Brazil the myth that NaCl damages hair is so strong that Unilever, P & G, L’oréal etc. sell “special” shampoos in our market – without sodium chloride.

  • Desiree December 9, 2013, 7:42 am

    I have relaxing my hair since I was a teeneger, we dont need a special shampoo, but it is better to use a moisturizer shampoo and conditioner,
    because relaxing makes the hair dryer, thiner and fragile, if you dont take good care of it.

    Hope that helps

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