Which chemical is commonly used in hair relaxers?

Sodium hydroxide is commonly used in hair relaxers due to its strong alkaline properties that effectively break down the protein structure in the hair. This process allows the hair to be straightened by altering its natural curl pattern.

Sodium hydroxide is particularly effective for coarse or curly hair types, as it provides a more significant level of straightening compared to other relaxers. When applied, it penetrates the hair and opens the cuticle, which helps in reshaping the internal structure of the hair.

Other options, while sometimes used in different formulations, do not serve as the primary agent in most chemical hair relaxers. For example, calcium hydroxide is often a part of the "lye-free" relaxers, while ammonium thioglycolate is primarily utilized in permanent waves and soft curl permanents rather than in straightening hair. Potassium hydroxide can be used in some relaxers, but sodium hydroxide remains the most prevalent and effective choice for achieving straightened hair in a typical salon environment.