Afro 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.

Hair relaxing can be performed by a professional cosmetologist in a salon, 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 treatment (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.