Final answer:
The active ingredient in alkaline permanents is ammonium thioglycolate, which breaks the hair's disulfide bonds to achieve curling. Sodium hydroxide, often associated with lye or caustic soda, is an inactive ingredient used in different products like toothpaste.
Step-by-step explanation:
The active ingredient in alkaline permanents is typically a compound called ammonium thioglycolate. This chemical is responsible for breaking the disulfide bonds in the hair's keratin structure, allowing the hair to take on a new shape when wrapped around perm rods. Alkaline permanents offer a more enduring curl than acid perms and are suited for hair that is more resistant to curling. However, they must be used with care as they are more damaging to the hair than acid perms.
It is important to note that sodium hydroxide is not the active ingredient in alkaline permanents; rather, it is used as an inactive ingredient in some other products like toothpaste. For example, sodium hydroxide is listed as an inactive ingredient in Colgate Total toothpaste, where it serves a different purpose.