While the word "perm" evokes thoughts of curly hair, the truth is there are a number of perms available that affect hair structure in different ways. In its most basic form, a perm, or permanent wave, uses chemicals to break down the chemical bonds that make the hair naturally straight, wavy or curly. Then the hair is restructured into the desired appearance.

The hair is composed of keratin, which at its most basic form is a protein structure that features many bonds to give hair its strength and ability to move. When permanent lotion is applied to straight hair using a permanent wave method, the cystine and sulphur bonds of the hair are broken. To accomplish a wavy effect, a stylist first wraps the hair around curlers or rods. For a loose, wavy effect, the hair is wrapped around large rollers. For tighter curls, the hair is wrapped around rollers that are smaller in diameter. Then the stylist applies thioglycolic acid and ammonia. This affects the hair structure by releasing the cystine and sulphur bonds from being straight.

During a perm, the bonds that the give hair its structure are broken then reestablished to change the texture. To accomplish this, a stylist applies another solution, known as a neutralizer. Because a neutralizer can damage the hair if too much is applied or if it is left on for too long, the stylist must closely monitor the perm process. The neutralizer re-establishes the bonds in their new shape, whether wavy, curly or ringlets. The stylist should thoroughly wash away the neutralizer to prevent any damage.

One by-product of perm lotion is that your hair might be slightly drier afterward. When the bonds are broken down, some moisture is released from the hair's cuticle and temporarily dry hair may be the result. Get a perm only if your hair is healthy and not dry, because the result can be split or dry ends and other hair damage.