Monday, August 29, 2011

Shampoos, Harsh, Mild and Otherwise

I've examined a number of shampoos (those that I had, I did not buy any for this project) to test the notion that certain detergents (surfactants) are harsh and others are not. I did this through examination of hairs in the shampoo under a transmitted light microscope, in comparison to those hairs dry or in distilled water. When hair is well-saturated with water, it swells. But different hair swells different amounts. Hair treated with coconut oil doesn't swell as much. Fine hair doesn't swell as much. Undamaged hair without many porosities swells less than damaged hair. I measured some hairs, dry vs. wet and found quite a difference in the amount of swelling in water.
Pufferfish, all puffed up.
Pufferfish, not yet puffed up.
Never the less, water alone makes hair swell and in so doing, causes the normally-flat cuticle to lift and this creates porosities for things to leak out or diffuse in. Wetting hair alone has a "damaging" quality. Think of a pufferfish to get the right image of what happens to the cuticle when the hair swells.

Some shampoos dramatically increase this swelling. Detergents are "wetting agents" they make water - which dissolves so many things, even more "wet" and allow more things to be washed away by water. That's an oversimplification, but it's good enough for now because the pictures are the feature of this post. Detergents also can remove oils and soils. Some detergents are very good degreasing agents and some are not. The latter are the ones you want for your skin and hair. Clean is good, but too clean is irritating!

Now the fun part:
These hairs are mostly normal porosity or not porous - not chemically treated but have some damage from sun/heat from the sun, combing and brushing and daily life. I have placed them in what some people call a "sulfate shampoo" (see below).
sulfate shampoo

sulfate shampoo, arrows show raised cuticle


Green/yellow stripes from shampoo uptake

Shampoo with ammonium lauryl and laureth sulfate. Do you see the frilly and ragged edges? You might not want to do this too often. The picture directly to the right is a white hair which has actually held on to the color of the shampoo after rinsing (it was green). These are very effective degreasing detergents.

This is a shampoo with decyl glucoside, lauryl glucoside and cocamidopropyl betaine - Burt's Bees Super Shiny shampoo. Very little visible change taking place. The "glucosides" are regarded as mild - not strong degreasers but good "wetting agents." You can see the cuticles appear to lie smoothly and the edges do not look ragged or frilly.
Burt's Bees

Burt's Bees

Soap bar

This is hair in the "suds" or lather of a soap bar. The non-porous, very fine hair (at left) fared worse than the coarser (thicker) hair shown below. The pH of soap and shampoo bars is high because of the reaction of oils and fats with lye or another hydroxide (strong base) which is how you get oils/fats to turn into soap. This is harsh to hair. Rinsing will immediately begin to restore the hair to its own pH and the hair begins to look normal again. An acidic rinse will speed that process (though both acids and bases can damage hair), and also help remove soap scum which accumulates when oils in soap bond to minerals in hard water.
soap bar

soap bar
Dilute C12-14 olefin sulfonate 
Dilute C12-14 olefin sulfonate

To the right are hairs in a shampoo containing olefin sulfonate, which can be a strong detergent under some circumstances.  It removes oils and soil quite well. This particular shampoo, however, has conditioning agents added and a low concentration of detergent, so you don't see much happening. Concentration matters as much as the actual "harshness" or effectiveness of a detergent.
Concentrated C12-14 olefin sulfonate - see edges
of hair for raised cuticles due to swelling. This is
an ordinary concentration for shampoo.

At left is a hair in a shampoo with a higher concentration of olefin sulfonate which contained a small amount of oil, but not enough to mitigate the shampoo's harshness. Again you can see the ragged edges at left and "lifted" cuticle at right.
Concentrated "mild" shampoo

Above, right is a hair in a "gentle" baby shampoo with decyl glucoside. The detergent may be gentle, but it is concentrated shampoo with a high percent of detergent and you can see the ragged edges showing in the hair's cuticle. Below is a shampoo with the same detergent, but it has been diluted (and thickened, which causes a slightly cloudy appearance). There is little apparent change in the hair in the diluted shampoo. The dilution or reduced concentration makes a harsh detergent less harsh. Even so-called mild detergents can be harsh if they are not diluted properly in a shampoo formula.
Dilute mild shampoo
I don't mean to give the impression that shampoo is all bad! It cleans the scalp and hair more effectively than just water. Dilute shampoos with mild detergents are not very damaging to hair (visibly, anyhow) and do a good job of cleaning soils and excess oils. Even one of the harsh shampoos can be diluted at a rate of 1-2 teaspoons of shampoo in a cup of water (or halve that if it's too much volume) for a shampoo that won't cause as much stress. If you shampoo your hair daily or every other day, you might consider diluting your shampoo or choosing a mild one. The same applies to colored (dyed) hair, chemically treated hair, curly or wavy hair, or hair which gets a lot of sun or heat styling. If you want healthy, strong hair, wash it less often. Washing with a gentle or a diluted shampoo should put less stress on the hair, leading to less damage. Even an occasional wash with a full-strength detergent with good degreasing properties isn't going to "ruin" already healthy hair.


  1. I love all your posts! I don't comment often, because when I get to the end of an article, I find the "You might also like", and I'm off reading another article, and not commenting :)

  2. We're actually talking about the same thing! Hair does swell with water if it is saturated with water for enough time. A quick shower probably won't do it. People who work with hair for the purpose of creating cosmetics have this measured. If you were to put a hair in a glass of water and dunk it, then remove it and look at it under a microscope, you wouldn't get much change. But if you leave it there for 15 or 30 minutes, you will get a measurable change. I've done this. BUT it's not a dramatic change. It is enough to put tension on the hair strands - like a swollen ankle. Tension (strain) is damaging. If you cause the hair to swell dramatically (like I did in the photos for this blog post) by putting them in undiluted shampoo, then the cuticles pop up - but that is a result of the sudden, detergent-related swelling, there is no hinge. If you covered a balloon with Post-it notes and blew it up - this is what I mean. They would all stick out a bit. Besides that, the cuticles are covered with an epicuticle membrane, by 18 MEA (a chemical-resistant lipid) and sebum from the scalp. It is a complicated system.

    But the idea that you can "open your cuticles with water, heat, baking soda, etc." is based on an oversimplified notion of hair. Nor can you "close" the cuticle with acids. You CAN make a pH environment for hair with vinegar or citric acid which is more like that which hair "likes" to be at and in which state it is more resilient to damaging forces. But that's it. If hair were really that fragile (that you could open and close the cuticles willy nilly) it would not serve its purpose very reliably and would have terrible resilience.

  3. Thanks for the great explanation! I get it now. :)

  4. Hey, I was wondering about your thoughts on bentonite clay (clay washes in general) or bentonite clay and apple cider vinegar mixture as a hair cleanser?

    1. Hello Sue,
      In a nutshell, vinegar is not a very good hair cleanser, though it can help remove excess oil - like if you used an oil treatment and washed it out - but your hair still felt a little bit oily. In that case a vinegar rinse might help.
      Clay can be a fairly good cleanser, but a mild one and not always easy to rinse out. I am planning a blog post or two about clay soon.

  5. I am excited about your clay cleanser post. I am not having the best luck with shampoos. I tried diluting Kinky Curly (you recommended it as a good cleanser to remove silicones and polyquats) and Trader Joes Tea Tree Shampoo with no luck. Both made my hair feel dry and matted. However, I also tried equal parts bentonite clay and a vinegar mix (I read on line that the vinegar makes the clay ph neutral) and I liked it.

  6. Hi, I have low porosity 3c/4a hair that loves glycerin but always seems to tangle near the roots. I read your article on conditioner cling and I figured that was probably my problem. I'm thinking about skipping the conventional conditioners all together and just sticking to a diluted shampoo to wash my hair. My plan was to treat my hair with coconut oil before I wash, wash with diluted shampoo, apply a an aloe vera + glycerin +grapeseed oil mix while its wet and put olive oil eco styler gel on top for a wash and go. I know my hair loves aloe+glycerin+eco styler because I bought a curl activator gel before with aloe + glycerin as the top ingredient and I got the best results from it (I would continue to use it but I only get 3 uses out of an 11 dollar jar which is too much imo). I also noticed that when I use conditioner my hair is detangled but it never feel much different that when I just use shampoo, It gives weight but not much else. My question is do I use a clarifying shampoo or a moisturizing shampoo in my dilution as you mentioned claifying shampoos maybe ne better for fine.tangled hair (which I have) but moisturizing/mild shampoos are better for being diluted. If It helps I was planning on using a clarifying or mild shampoo from the brand Klorane.

    1. Hello Salx,
      I remember when I tried going "conditioner-free" the thing I missed was the weight that conditioner adds, as you mentioned.
      My inclination is to say - dilute whatever shampoo you have at home already. Something you are familiar with. Rather than buy something new - see if diluting the shampoo gives you a result you want first and if it's going to be something you like to do or something that annoys you in the long run. You shouldn't have to dilute a mild shampoo too much, although some sulfate-free shampoos are pretty concentrated and do need diluting to be truly mild to scalp and hair.
      Some clarifying shampoos are going to leave a tacky, tangly feel and that is not a good choice for hair that tangles easily. The "after-feel" of a shampoo may be your greatest guide in which shampoo to use (and dilute). That's more likely to be a problem in a shampoo with absolutely no conditioning ingredients. From Klorane, it would probably be best to choose one of their mild and/or moisturizing shampoos to be sure it will not promote tangles. Good luck! W