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 the uptake of oxygen and 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.