Final answer:
Hydroxide relaxers permanently straighten hair through a chemical straightening process involving a reducing agent like ammonium thioglycolate to break disulfide bonds, followed by physically straightening the hair and applying an oxidizing agent such as hydrogen peroxide to reform the bonds.
Step-by-step explanation:
The process by which hydroxide relaxers permanently straighten hair is known as chemical straightening or relaxing. In this process, a reducing agent, commonly ammonium thioglycolate, is applied to the hair. This substance reduces and breaks some of the disulfide bonds within the hair's keratin structure. Disulfide bonds, which are strong covalent bonds created by the oxidation of sulfhydryl groups on cysteine residues, play a crucial role in maintaining the hair's natural curls or waves.
After the application of the reducing agent, the hair is then physically straightened and an oxidizing agent, often a diluted solution of hydrogen peroxide, is used to reform the disulfide bonds in their new, straightened positions. This reformation of disulfide bonds ensures that the hair remains in its straightened state until new hair growth occurs.
It's important to note that this chemical alteration is permanent on the treated hair and does not revert except through natural growth or further chemical treatment. The hair's newly straightened structure will remain until it is eventually cut or grown out, and the process must be repeated on new growth to maintain the straightened appearance.