Perms can take between 1 and 2 hours, depending on how long the hair being permed is and what perming technique is implemented by the stylist. Once complete, a perm is not completely settled until about 28 hours have passed.
If an individual's hair is conducive to the procedure, perms take less time. Hair that performs best is natural, neither highlighted nor colored. The perm itself can last up to 6 months if it is well-cared for. Since they last so long, performing them is an intensive chemical process. This is why undamaged hair, which is less porous, performs best and takes the least time for a perm.