Final answer:
Alkaline perms are updated versions of the cold wave perm developed in 1941, which used a thioglycolate-based solution to permanently restructure the hair without heat.
Step-by-step explanation:
Today's alkaline perms are modern versions of the cold wave perm method developed in 1941. This method represented a significant advancement in the chemistry of perming hair, utilizing a thioglycolate-based solution that does not require heat to process.
This chemical solution breaks down the hair's disulfide bonds and, when the hair is wrapped around forms and the solution neutralized, new disulfide bonds are formed, creating a permanent hairstyle that can last for several months. The cold wave perm allowed for the restructuring of hair without the use of thermal tools, which marked an evolution from earlier methods of perming such as the spiral and croquignole perms.