In chemical science shampoos are simply “surfactants”. A surfactant is a substance capable of emulsifying (meaning to loosen up and hold) fats or oils. The emulsifying properties of shampoos allows them to rinse out oil and dirt with water when you use them. Shampoos in many regards are like detergents. In fact most commercial shampoos are nothing more than sophisticated detergents. The major difference between the shampoos we wash our hair with and the detergents we wash are clothes with are the bleaching and softening agents.
Shampoos are composed of mostly water ranging from 65% to 75%. The rest of the shampoo consist of surfactant (detergents) which are the reaction products of lye (caustic), lauryl sulfates, sodium lauryl sulfates, ammonium lauryl sulfates and animal fatty acid extracts such as tall oil, lard, or vegetable oils like coconut oil, and other plant fatty oils. In theory these surfactants when massaged into the scalp and hair under constant water flow should interact with the oils and dirt and to remove them from the hair.
Ever read the ingredient listings of many commercial shampoos
lately? The list is so long with words you cannot even pronounce
let along know what they mean. The truth is to clean hair
effectively all you need is a few surfactants that are not harmful
and easily rinsed out. Most people think that because a shampoo
does not lather really thick and lasting that it is not doing the
job. Scientifically, decreasing lathering is what you would expect
as you clean your scalp and hair with a shampoo that does not
contain additives. Ever had a sink full of bubbles made from a
liquid detergent mixed in warm water and then put oily dishes into
the soapy water? Notice how the bubbles slowly start to fade away
the more you wash the dirty dishes? The bubbles are being reduced
but the dishes are getting cleaned! However, companies know that
when we wash dishes or clothes we expect to see a lot of
bubbles. This gives us the impression that the clothes and dishes
are getting really clean. Yet, this is not always the case (just
use a cheap $1.50 cleaning product and you will see!). Likewise, we
aesthetically expect the same thick rich bubbles when we wash our
hair. So companies add additives such as foaming and thickening
agents like alkanolamines and methyl cellulose to help stabilize
the lather and to make it thick and rich.
Most commercial shampoos use cheap and sometimes harmful starting materials that have very short shelve life due to oxygen uptake and the possible growth of bacteria. To offset the lack of product stability companies add many preservatives like paraben, methyl paraben, DMDM hydantoin, and Vitamin E.
Many of the hair and scalp problems caused by commercial
shampoos can be traced to the additives used to make the products
more effective and stable (although new R&D data suggest that
lauryl sulfates may be immunosuppressive agents). Because of the
chemical nature of these additives and the chemical and rheological
make up of human hair some of these additives can be left behind on
the scalp and hair after shampooing. Continuing use of these type
shampoo products ultimately will result in the significant build up
of many of these chemical substances. This build up eventually
leads to less efficient shampoo cleaning because the surface area
of the hair has been modified chemically which reduces the
surfactant effect of the shampoo resulting in oil and dirt build
up. Even more so many of these additives are not stable to the
natural bacteria found on the surface of human skin (scalp).
Bacteria ultimately will breakdown these chemical additives into
products that are known irritants and corrosives. Such long-term
use of such shampoo products lead to hair breakage, scalp damage,
and potential hair loss.
A good shampoo should never contain lye or sulfates and only the softest of fatty acids such as olive oil and palm oils. As for stability against bacteria growth it is a known fact that shampoos that contain significant concentrations of glycerin and citric acid will not sustain bacteria growth. These shampoos don’t lather very long when used but they do clean your hair and have no deleterious effects on hair viability and scalp health. You can always wash your hair a second time if you think further cleaning is needed.
