TUTORIAL: Part Two: The Physical Properties of Hair Cleansing (Shampoo)

As we begin, remember this: The purpose of a DETERGENT is to reduce the surface

tension of water.. Detergents make water "wetter". Unlike traditional soaps, they leave

no dulling "scum" residue in the hair. Simply wetting hair with water, does not create

a true cleansing action because the hair fiber at first, wants to resist the penetration of

water. Water alone cannot break up various oils, sebum, styling aids and other materials

from the hair and scalp. To cleanse the hair, we must "wet" the hair. THAT is the action

of a good shampoo.

In shampoo, detergents weaken the bonds sticking soil and sebum to the hair.. particularly

to the epicuticle, which must be protected and left undamaged. Surfactants are compounds that are both hydrophilic and lipophilic. They are composed of a long fatty acid chain. Sufactants react with oxygen, which stabilize bubbles and forms lather.

These interactions create almost a "vacuum cleaner" effect. The lather, in part, draws both

liquid and solid debris from the scalp surface and from the hair... it "sucks" the dirt away

from the hair and into the shampoo solution