Ammonium thioglycolate is the main ingredient in:

Ammonium thioglycolate is primarily known for its role in the perming process. It acts as a reducing agent, breaking down the disulfide bonds in hair, which allows the hair to be reshaped into curls or waves when the hair is wrapped around a perm rod. This chemistry is fundamental to creating permanent curls, making ammonium thioglycolate essential in this context.

While it may also find usage in a variety of hair treatments, its most notable and common application is in permanent waves or curls, where it provides the necessary property to alter the hair structure temporarily. Therefore, associating ammonium thioglycolate mainly with curl rearranging is accurate given its strong connection to achieving and maintaining perm results. Other treatments have different primary ingredients or effects that do not primarily utilize ammonium thioglycolate in the same manner.