ABSTRACT
Hair straightening is a common practice among individuals with kinky hair.1 The hair can be straightened with heat or chemical techniques.2 Heat straightening techniques are temporary and have already been covered on page 67. This chapter discusses the permanent method of hair straightening, also known as lanthionization. Hair straightening is undertaken for many reasons including those listed in Box 6.1.3
The first permanent hair straighteners, also known as hair relaxers or perms, were developed around 1940 and consisted of sodium hydroxide or potassium hydroxide mixed into potato starch. Once the disulfide bonds were broken, the hair was pulled straight and the disulfide bonds reformed in their new configuration. This chapter examines the physical and chemical differences between African-American hair and Caucasian hair, discusses the chemistry of hair straightening, reviews the unique aspects of the hair straightening techniques, and presents the relevant dermatologic considerations.
