What is the role of chemical properties in the process of perming or relaxing hair?

In the process of perming or relaxing hair, the chemical properties play a crucial role in creating reactions that alter the structure of the hair. This involves breaking and reforming the disulfide bonds within the hair's cortex, which is essential for both perming (adding curls) and relaxing (straightening) the hair.

The chemical solutions used, whether they are for perming or relaxing, contain specific agents that interact with the hair's keratin structure, allowing the stylist to reshape the hair. For instance, in a perm, the hair is treated with a reducing agent that softens the bonds, making it pliable to be reshaped around curlers, and then neutralized to lock in that new shape. Conversely, relaxing solutions use alkaline agents to straighten and elongate the hair's natural curl pattern.

The focus of this question is on the fundamental requirement for chemical reactions to facilitate the physical changes in hair texture. This choice highlights the essence of chemical properties as they enable the transformation of hair by acting at the molecular level, setting it apart from options that pertain to aesthetics, hair density, or timing, which may be important but do not directly affect the chemical transformation process.