Relaxer

A relaxer is a type of lotion or cream generally used by people with tight curls or very curly hair which makes hair easier to straighten by chemically "relaxing" the natural curls. The active agent is usually a strong alkali, although some formulations are based on ammonium thioglycolate instead.

The first documented history of the relaxer began with Garrett Augustus Morgan in 1909. His hair straighten cream was found accidentally when trying to find a solution to ease friction of sewing machine in his tailor shop. Morgan tested his cream on a neighboring dog's fur. With the success of the cream, he established G.A. Morgan Hair Refining Company and began selling his product to African Americans.

Hair relaxing, or lanthionization, colloquially known as a perm, can be performed by a professional cosmetologist in a salon, a professional barber in a barbershop or at home with relaxer kits. As with hair dye, the treated portion of the hair moves away from the scalp as the new growth of untreated hair sprouts up from the roots, requiring periodic retreatment (about every 8–10 weeks) to maintain a consistent appearance.

The relaxer is applied to the base of the hair shaft and remains in place for a "cooking" interval, during which it alters the hair's texture by a process of controlled damage to the protein structure. The hair can be significantly weakened by the physical overlap of excessive applications or by a single excessive one, leading to brittleness, breakage, or even widespread alopecia.

When the relaxer has worked to the desired degree, the hair is rinsed clean. Regardless of formula, relaxers are always alkaline to some degree, so it is prudent to neutralize or even slightly acidify the hair with a suitable shampoo immediately afterward. The prompt use of hair conditioner is also important in order to replace some of the natural oils that were stripped away by the process.

Thio relaxers use ATG, or ammonium thioglycolate, which is also used in permanent waving, but at a much higher pH and concentration than used in permanent waves. It is usually higher than a pH of 10. These relaxers are also thicker with a higher viscosity, or thickness, which makes for an easier relaxer application. Thio relaxers break the disulfide bonds in hair, similar to the permanent waving process. When enough of the disulfide bonds in the hair are broken, the relaxer is rinsed from the hair and the hair is towel dried. After towel drying, a neutralizer of some sort is applied to the hair.

...
Wikipedia