Chemical Straightening: What it is: The most permanent of all of the smoothing methods, it can inflict the most damage on your hair. In this process, a chemical cream – often an alkali - is applied to “relax” the curls, breaking hair’s protein bonds. The problem with hair relaxing, according to Dr. Amy McMichael, Dermatology Professor at Wake Forest, is that over time, there is an overlap where the chemical is placed. “As we apply the chemical to the new growth,” she explains, “it overlaps with what’s already been treated, and as a result of that, all of those areas are a bit more weakened. Additionally, with chemical hair relaxers, many people will also use heat on top of it, so you end up compounding damage on top of damage.” Further, after chemical relaxing, washing your hair for a few days is discouraged, although conditioning is recommended to help avoid scalp irritation. Good for: Anyone with highly coiled, curly hair. Administered by: A stylist only. Trained professionals are best equipped to determine which process is best for your specific hair type. Lasts: Until the hair grows out.