A permanent wave is a chemical process o permanently curl hair. Hair is first washed with a clarifying shampoo to remove impurities and then wrapped around perm rods which size will determine the tightness of the curl. Chemicals in the waving solution break and reform the bonds of the hair structure. Once the waving solution is rinsed off, a neutralizer will set the new shape of the hair by reinserting disulfide bonds into the hair. You will need to wait 48 your to wash hair after a permanent wave or risk the loosening of the curls.