When choosing a perm style, consider the texture and length of your hair. Acid-balanced and alkaline perm solutions are used on different hair textures to create body and curl while moisturizing and relaxing the hair shaft. Hair length usually determines which perm rods will be used to create a curl or body wave.
If you have thin, fragile or color-treated hair, an acid-balanced perm solution is best to increase curl while moisturizing hair. Acid-balanced perm solutions have a pH level between 4.5 and 6.5 and require a heat source such as exothermic heat (chemical reaction within the solution) or a hood dryer to penetrate the hair shaft. While this solution will relax sooner than an alkaline perm solution, thin or color-treated hair will suffer less damage and become more manageable.
If you have hair that does not take a curl easily, an alkaline perm solution may be necessary to reshape the hair shaft so it can hold a curl or wave for an extended period of time. This solution penetrates the hair shaft faster than an acid-balance perm solution and takes longer to relax. The pH level of an alkaline perm solution is 8.2 to 9.6. No heat is necessary to activate the chemicals in an alkaline perm solution.
Choose a perm style that works well with your hair type and length. If you have long, healthy hair, a spiral perm is best because the result is long, cascading curls. If you have thin or limp hair, a root or body perm will give you loose waves or curls that add volume and body to your hair. If you have a bob or other type of single layered haircut, a stacked perm adds body and volume. Spot perms can be done on specific layers or sections of you hair if you want to increase your natural curl or if you want to add curl to hair tips.
The size of the perm rod determines the size of the curl or wave. Large perm rods are commonly used to create large curls and wavy perms. If you have long hair, large perm rods are the most useful in creating lots of curl. Smaller perm rods are used to create tighter curls. The length and style of your hair usually determines which perm rod size will be used as shorter pieces of hair cannot be wound around a perm rod as many times as longer hair. Consult your stylist to determine the best perm style for your hair length.