Sodium lauryl sulfate is known to most that have looked at the label of their shampoo bottle; it is a rather harsh detergent, meaning that it removes sebum very effectively. Since sebum protects the hair from drying out and conditions its surface, using SLS alone as a surfactant would lead to dry, fly-away hair. SLS is found in 90% of all shampoos and toothpastes. It is harmful if inhaled, ingested, left on skin too long, and it poses dangers to the eyes as it can accumulate in the tissues of the eye causing possible cataracts.
SLS is not very soluble in cold water and so cannot be used to make shampoos that look “clear”, so other related compounds such as ammonium lauryl sulfate or triethanolamine lauryl sulfate that are much more soluble are typically used in shampoos for dry or damaged hair. Sodium lauryl and sodium laureth sulfate are some of the ingredients said to aid in causing ailment such as cancer and other degenerative diseases.
But chemical Shampoos contain far more components than surfactants:
- There are thickeners (xanthan gum),
- preservatives (parabens),
- emulsifiers (glycol distearate),
- Color additives and foam boosters (cocamide monoethanolamine).
In some cases, a residue may accumulate, referred to in the trade as “buildup.” This has resulted in introduction of specialty shampoos claiming to eliminate the social horror of limp, sticky and dull hair.