What type of chemical is commonly used for permanent waving?

Ammonium thioglycolate is commonly used for permanent waving 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 curls or waves as it is wrapped around curlers and then neutralized. The effectiveness of ammonium thioglycolate in altering hair’s structure makes it a preferred choice in the permanent waving process.

While hydrogen peroxide and sodium hydroxide have their own applications in hair treatments—such as in bleaching or relaxing respectively—they do not serve the same purpose as ammonium thioglycolate in the context of permanent waving. Glyceryl monothioglycolate is another reducing agent that can be found in certain perm formulations, but ammonium thioglycolate remains the most standard and widely used chemical for this specific application due to its desirable properties and effectiveness in creating curls.