Chris Rock has been making the rounds to promote his new documentary "Good Hair," about the seriously complicated hair care customs of the African-American community. His film delves into the $9-billion industry that has evolved around this culture's attainment of the "European" look, since the natural nappy look just isn't cutting it. According to some reviews, the most entertaining aspect of "Good Hair" is its investigation of the history and practice of hair relaxers, which commonly use sodium hydroxide. After wowing us with its power to coax tight, kinky hair into long, luxuriant tresses, the film shows sodium hydroxide burning a hole through a raw chicken carcass and completely disintegrating an aluminum can that had soaked in a sodium hydroxide solution for several hours.

The chemical process of hair relaxing is no laughing matter. Hair breakage, hair thinning, hair loss, scalp irritation, and scalp damage are just some of the lovely side effects that accompany years of relaxing hair. Unlike products that promise to temporarily tame curls, the process of chemically straightening hair transforms the basic structure of each strand. The chemicals used in relaxers penetrate into the cortical layer, which is what gives curly hair its shape, and break the cross-bonds. In loosening the natural curl pattern, relaxing chemicals thus splinter hair's strength and elasticity. The process is irreversible.

Sodium hydroxide, a caustic chemical with a high alkaline content is the very same ingredient found in drain cleaners. While sodium hydroxide is the most popular and most potent type of chemical relaxer, guanidine hydroxide and ammonium thioglycolate are other options. Commonly referred to as the "no-lye" relaxer, guanidine hydroxide tends to be less damaging, relatively speaking. Ammonium thioglycolate, nicknamed "thio relaxer," reacts differently by softening and relaxing curly hair through changes to the hair's cystine linkage. No matter which version is used, all types of chemical processing can erode the hair and damage the cuticle.

It is recommended to find a reputable professional trained in hair relaxing and to arrange a consultation. After performing a strand test to ensure that hair can withstand chemical processing without adverse reactions, the hair professional typically applies a protective petroleum cream followed by a chemical hair relaxing solution, which must not come into contact with the eyes or exposed skin. Once the hair has fully "cooked," the chemicals are rinsed from the hair with warm water. The final steps are a neutralizing product to restore the hair's natural pH and a deep conditioner (either cream or protein/liquid) to repair damage. Depending on how long the relaxing solution is left on, the hair can stretch out to over twice its normal length when combed out. Needless to say, this long, straight hair is also extremely fragile.

Once hair has been relaxed, it requires specialized ongoing treatment to maintain the effects of straightening. Because relaxed hair is more porous and tends to retain dulling residue, hair products must be rinsed out thoroughly. It is also necessary to use leave-in conditioners and/or hot oil treatments (using almond, olive, or sesame oil) twice weekly since relaxed hair becomes much more brittle and breakable. Conditioners smooth the damaged outer surfaces of the hair and replenish the oils and proteins that chemical processing strips off. If not treated with attentive care, newly relaxed hair can become stiff and "see-through."

A touch-up either in the salon or with an at-home relaxer kit is necessary every 6-8 weeks to straighten ingrowing roots. Warning when DIY: overlapping the chemicals on already straightened hair can result in instant breakage. A strong salon relaxing treatment typically lasts up to 6 months depending on the hair's texture and growth. At this point, the costly cycle begins anew, over and over again. If it seems like an unhealthy addition, it is telling that regular hair relaxer customers in "Good Hair" refer to their chemical of choice as "creamy crack."

With "Good Hair," Chris Rock, who seems like an unlikely champion of women's beauty interests, untangles the knotty issues surrounding hair relaxing, among other hair treatments. Relaxers strip away the hair's outer layer and sap it of elasticity, causing strands to snap off when styling. Breaking and other damage is not uncommon. Nearly three-quarters of African-American women who have undergone chemical relaxers complain of hair breakage, split ends, and dryness. Misuse of chemical hair relaxers at home is particularly dangerous. In fact, the FDA lists hair straightening products among its top consumer complaint areas.

All of the time, energy, and expense necessitated by hair relaxing is devoted to the pursuit of one particular hair style, which once upon a time was out of fashion. At the root of Chris Rock's documentary are a number of hairy questions relating to racial identity in America. Nobody seems satisfied with the ethnic look, and everybody seems willing to suffer dangerous, irreversible salon procedures in the pursuit of some "European" ideal. But another take-away is the pure devotion of women in the African-American community to achieving their own notions of "good hair."