What's really in your shampoo | Salon
Consumers value shininess in nearly everything, including hair. For hair to shine, the cuticles of the hair must lie flat. Imagine a strand of hair as a stack of flimsy paper cups. When all the lips of the cup, called imbrications, lie flat, hair shines. Dull hair has the cups' lips sticking up. To get imbrications to lie flat, hair needs to be exposed to mildly acidic substances, so substances like citric acid are added to make the imbrications lie down and give hair that shiny look and to let yourself glow.
Consumers believe that thick is better. Which may explain why George Bush was a two-termer. Shampooers trust the velvet heft of the shampoo in the palms of their hands. So five of the 20 ingredients on the list are there because they help thicken the soap. Thickness also guarantees that people use more shampoo than necessary. There's salt, glycol distearate, cetyl alcohol, ammonium xylene sulfonate and others: body on tap.
And where would we be without suds? Cleaning agents do tend to foam a little when they're used, but the bubbles don't affect the cleansing much. However, the extra lather helps convince the shampooer that the soap is working. Lathering agents are added to boost the suds, chemicals like cocamide MEA. This little devil, besides being toxic in a few ways, also helps the lather to stay once it's been raised, a sudsy Viagra, with the help of known associates like the plastic PEG-7M. Great lather for great-looking hair.