What type of chemical is commonly associated with permanent wave treatments?

Ammonium thioglycolate is the chemical commonly associated with permanent wave treatments because it acts as a reducing agent that breaks down the disulfide bonds in the hair's keratin structure. This process allows the hair to be reshaped into a new curl pattern or wave. It is widely used in various perm formulas due to its effective reformation of the hair's structure, enabling long-lasting curls or waves when the hair is wrapped around rods.

The other chemicals listed do not serve the same purpose in permanent wave treatments. Calcium hydroxide is often used in relaxers and does not effectively create curls. Sodium bicarbonate is primarily used as a mild alkaline agent and does not participate directly in the perming process. Glycolic acid, while useful in other hair treatments, is more associated with skincare and does not contribute to the curling effect seen in permanent waves. Thus, ammonium thioglycolate is the ideal choice for achieving the intended results in permanent wave treatments.