Let’s talk about Sulfates in Shampoos!
What are surfactants?
Shampoos use systems of surfactants like anionic, cationic, amphoteric, or non-ionic types to cleanse the oil and debris, and the combination of these surfactants can greatly impact the hair. Certain surfactants like sodium lauryl sulfate (SLS) have gotten a bad reputation over the years. Do they deserve it? Turns out the truth is not so black and white.
SLS is an anionic surfactant, which is really awesome at getting rid of sebum but can potentially cause an increase on electrical negative charge on the hair surface, increasing frizz and possibly friction.[1] Some studies have shown SLS-induced damage to the hair cuticle, depending on the surfactant’s charge density.[2,3] BUT, just knowing that SLS is in a shampoo does NOT tell you the whole picture: 1) you have to look at the whole system of surfactants and how they interact and 2) shampoo isn’t the biggest contributor of color loss (spoiler alert: it’s water!)
Do surfactants impact color in your hair?
Do surfactants zap color from your hair? Some sulfate shampoos can, but the crazy thing is that some sulfate-free shampoos can too! It all depends on the formulation: surfactant type and load, surface tension, other shampoo ingredients, and pH of the shampoo. An SLS containing shampoo may also contain other surfactants like cationic, amphoteric or non-ionic, to make the cleanse more gentle. One ingredient does not define the formulation. As far as color fading goes, being “sulfate free” alone is not enough to guarantee color preservation. In fact, studies have shown equal color fading in shampoos with variable amounts of surfactants and with water exposure alone! [4]
What can I do to preserve color treated hair?
Rather than focusing on sulfate free vs. not, more important factors for hair color include:
- UV and heat protectant (hats, UV or heat protectant sprays)
- minimizing water exposure (use dry shampoo to lengthen time and swim caps)
- maximizing hair health. When you do wash, focus on the scalp and try not to get shampoo on the mid to ends which fade the fastest.
How do I choose the best shampoo for my hair type?
Who can benefit from sulfate-containing shampoo? Those with oily scalps, those who love a foaming shampoo, those who enjoy a deep cleanse, and those with fine hair.
Who might want a sulfate-free shampoo? Those with dry sensitive scalps (for ex: if you have eczema, ichthyosis, allergic contact dermatitis to SLS, etc.), those with dry, coarse, curly, or frizzy hair.
What if you have color-treated hair? Since we debunked Sulfate free shampoos here, how do we know what to use? Valerie @cosmetic_chemist shared with me to look for shampoos that are advertised as gentle, color safe, and low foaming. She also gave the expert tip to look for an ingredient called amodimethicone which is a “color protecting hero.”
At the end of the day it also comes down to your hair type and your preference. What’s yours?
Special thanks to @cosmetic_chemist (Valerie formulates hair products for a living – check out her page for tons of info!), @_janetsui, and @theecowell for educating me about this topic and contributing to this post.
Sources:
1 PMID 25878443
2 PMID 25277290
3 PMID 20815023
4 Evans, Trefor “Quantifying hair color fading” 2015 (link)
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