The detergent of a hair shampoo remove dirt from the hair and scalp, as well as enough accumulated sebum to keep the hair looking clean, but not so much as to remove all of the oil. The moderate detergent action of the lauryl sulfates and related surfactants accomplishes this tightrope act very nicely. Many shampoo formulations contain added conditioners to replace at least part of the lubricant that might be lost during washing. Other shampoo ingredients help stabilize the foam, act as preservatives, give the shampoo itself a pleasing viscosity or body, adjust the pH, chelate the metal ions of hard water that might degrade the surfactant's action and add color and fragrance.

Do You Know?

       Besides good genes and proper care, the acidity of the shampoo plays a part in the production of good luster and resilient hair. Other things being equal, a strand of hair is strongest under slightly acidic conditions, at pH of about 4 to 6. The scales of the cuticle tend to swell up and fluff out under basic conditions. This condition causes reflected light to scatter, making the hair look dull. A tight, slightly acidic cuticle reflects light more coherently, thus giving the hair a pleasant luster.

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