Monday, October 3, 2011

How to Tame a Strong Shampoo

If full-strength, inexpensive shampoos are harsh on hair, stripping off natural oils and leaving the hair without protection so that it can lose moisture and other vital components, then is the only solution to buy shampoos with mild detergents? What if they're all too expensive or smell bad? Can there be a compromise in a market in which vilifying ingredients and marketing the more-expensive alternative is lucrative and not necessarily beneficial to the customer?
©Science-y Hair Blog 2013
As I tried to show in this post, yes and no. If a “mild” detergent is highly concentrated in a shampoo, it will still be harsh (cause the hair to swell and remove too much oil). It’s the same with hot peppers, a lot of red chilies (pretty hot) are going to make your eyes water as much as a little Serrano (super-hot).©Science-y Hair Blog 2013

Yes, I know - some people don't use shampoo at all and it's much better if you shampoo every other day or less often. But some of us need to remove product residue, wash off allergens, or keep the scalp scrupulously clean to prevent flare-ups of skin disease. Never the less, over-cleaning is bad for anybody's skin and hair and rinsing all that detergent down the drain isn't doing the Earth's water supply (or your local water treatment plant) much good. ©Science-y Hair Blog 2013

Solution: dilute your shampoo. Before you go shopping for sulfate-free shampoos (and I bet you'll probably try 2 or more before you find one you like), consider the power of dilution. What is troublesome for the sensitive-skinned person about "sulfate-free" shampoos is that they can be hard to find, tend to cost more, and can have herbal ingredients or preservatives which can trigger allergies and skin sensitivities. If you have a shampoo you like and want it to be milder - you can make the shampoo you already have into a mild shampoo. Nifty!
©Science-y Hair Blog 2013
How to dilute shampoo: 
I tested some dilutions on real hair to come up with a dilution for a standard commercial shampoo. I kept lowering the amount of shampoo in the shampoo-water ratio until the mixture did not cause visible swelling leading to cuticle “lifting” and therefore hair damage or drying.

I used “Prell” shampoo with Ammonium lauryl and laureth sulfate. The dilution rate I ended up with was 1 teaspoon (5 ml actually 1-2 teaspoons) shampoo in 1 cup (about 250 ml) water. I expect that a similar dilution is adequate for most commercial shampoos.

Here are some pictures to show the differences.©Science-y Hair Blog 2013

Full strength, "strong" detergent. Frilly, rough surface is the cuticles of the hair being pushed outward as the hair swells in the shampoo.
Same shampoo as above, diluted at a shampoo:water ratio of 25:75 or 1/4 shampoo and 3/4 water.

©Science-y Hair Blog 2013
Strong detergent, diluted 1-2 teaspoons shampoo in
1 cup water showing much less disruption in the cuticle

A combination of "mild" detergents at very high concentration,
the "frilly" edges indicate hair damage.
©Science-y Hair Blog 2013
The same mild detergent combination diluted at a rate
of 1-2 teaspoons shampoo in 1 cup water. You can see that the
cuticles look more flat like shingles on a roof - this is normal. There
is some debris stuck to this hair that looks like cuticles sticking up.
It isn't - it's road dust. A little agitation will remove it.

©Science-y Hair Blog 2013

So can you use any shampoo without hair damage or drying? By the looks of it, you can. Only experience will tell you whether this cleans as well as you’d like or leaves your hair feeling stripped.
©Science-y Hair Blog 2013
This is ideal for is buying inexpensive shampoo and diluting it so it will be more gentle to your hair. If you buy a small bottle of an expensive shampoo to dilute, whatever conditioners and “goodies” have been added will be too dilute to do much good. But considering that conditioners are added to shampoos to help mitigate the damage caused by strong or concentrated detergents, diluting does that for you already, so why spend more?

Travel-friendly: This is also a good solution for when you are traveling and need to wash your hair but don’t have your usual products with you.

Harsh-feeling sulfate-free shampoos: If you have bought a "mild" shampoo and find it to be truly drying, try diluting it to see if you like it that way.
©Science-y Hair Blog 2013
I dilute shampoo in a large plastic cup in the shower, I pour in the shampoo, let the shower spray do much of the mixing, stir with my fingers, and pour it over my head in sections. It could be done in a plastic bottle with a cap to shake the mixture up. It will be watery and not as foamy – in other words, not what you’re used to in a shampoo. But if you can get over the watery texture, this is a great way to shampoo your hair with minimal damage and avoid paying more for "sulfate-free"shampoos.©Science-y Hair Blog 2013


  • Do not dilute dandruff shampoos if you are using them for itchy scalp or flaking. You’ll dilute the medication and render it less useful. 
  • Do not dilute shampoos in their original bottles, this will dilute the preservative and can result in bacterial growth. 
  • If you want to dilute a small amount of shampoo to leave in the shower, boil the water first (or use distilled water), mix the shampoo in gently when the water has cooled enough to touch, store in a bottle cleaned well with vinegar, rubbing alcohol or diluted bleach. This should be safe to use for a week or two, but do not use it if it changes in any way - in color, thickness, odor, or separation.©Science-y Hair Blog 2013

The take-home message: If you want to make a full-strength shampoo more mild and gentle, mix 1-2 teaspoons of shampoo (5-10 ml) in one cup water (250 ml). If this is more than you need, you can easily cut the "recipe" in half or fourths.©Science-y Hair Blog 2013


  1. Thank you for this post! It's great..

    Another trick I use is to mix 1 part shampoo with 3 parts conditioner (preferably silicone free) in my palm prior to application. I swirl and swirl them together until they are properly mixed and then use that mixture to clean my hair. I find that to be as effective as purchasing some of the more expensive shampoos that are full of oils and proteins and whatnot to mitigate the damage caused by the surfactants in the shampoo, but more satisfying than merely conditioner washing because I'm giving it a chemical boost and getting a cleaner feeling scalp.

  2. I have done this too. It works well and is certainly budget-conscious. Thanks for commenting!

  3. "If you have a shampoo you like and want it to be less mild ..." I was thinking it should say "more mild"?? But might be reading it wrong, lol!

  4. Thanks, unknown! Nothing like a good typo to make me blush. WS

  5. would 3% of texapon in 500ml aloe vera be diluted enough to be safe? I just found I've been lied and that my "all natural" shampoo has texapon, it's the best I have found so far and worry I'm damaging my hair by using it.

    1. Hello Gabriela,
      Texapon (sodium laureth sulfate) - your supply is a liquid? I think that the liquids are usually supplied at 70% active ingredients, but there are other concentrations, depending on your supplier.
      3% in 500 ml will be 15 ml by volume, but usually this is done by weight in order to be accurate - so 15 g sodium laureth sulfate per 500 g aloe vera.
      The detergent probably needs to be mixed with water, first, even if it is a liquid. Unless you're accustomed to adding detergents to aloe vera (juice? gel?) and know how it will perform. Undiluted aloe vera juice can be a little too acidic.

      If your "raw ingredient" is 70% active ingredients, 3% should give you a mild shampoo, though that requires first knowing how well your hair responds to that much aloe vera. Aloe can make some people's hair act dry and stiff if it is too concentrated.
      If your raw ingredient is 50% active ingredients, you might not get much detergency with 3%.
      A shampoo made with aloe and 3% detergent will be watery and will probably leave your hair feeling tangly. Some of the thickeners (including salt - sodium chloride) in shampoos give them some extra "slip" for hair so it doesn't feel tangly. That's why formulas for shampoos tend to be not 100% natural - they don't give us the experience we're used to. Good luck with your formulating - WS