Hair is made of keratin, composed of long molecular chains within the cortex layer of hair. These chains form a twisted rope-like fiber which has a network of cross-bonds or links that provide stability, strength and elasticity to hair.

There are two types of bonds:

• hydrogen bonds
• cystine or sulphur bonds.

Permanent waves change the hair from straight to wavy by breaking these cross bonds. When hair takes on its new shape, the bonds must be re-established for curl to be permanent.

The classic permanent wave solution or “cold wave” lotion is generally thioglycolic acid plus ammonia, which causes the cystine or sulphur bonds to be released. When hair is wrapped on the rod, this solution is applied. A certain amount of time is required for the hair to take on the shape and size of the rod. This is called “processing time”. The stylist must be able to determine how much time is needed to achieve the type of curl desired, otherwise hair can be underprocessed, resulting in curls that relax too soon or overprocessed, resulting in too curly or frizzy hair. Once the hair is “processed” the stylist applies a neutralizer while hair is still on the rods. Image by MrFlip

The neutralizer provides a dual chemical action, neutralizing and oxidizing which results in reforming the cystine bonds and the hydrogen bonds so that the hair stays curled. The neutralizer forms new hydrogen bonds to shrink or harden the cortex and cuticle layers of the hair. The cystine bonds are reformed by oxidations that occurs between the sulphur in the hair and the active oxygen atoms in the neutralizer. When the cystine bonds are reformed, the wave remains permanent.

After all the neutralizer penetrates the hair, hair is unwrapped carefully and rinsed thoroughly with water and now hair is ready to style. For best results, perms should be done by a salon professional.