Since all texture services require the stylist to physically and chemically change the structure of the hair. Let’s begin by reviewing the hair structure and its purpose. There are three layers: the cuticle, the cortex, and sometimes the medulla that create one strand of hair.
The outermost segment of the hair shaft consists of a hard, shingle-like layer of overlapping cells, approximately five to 12 cells deep. This layer is formed by dead cells arranged in a scale-like formation. The cuticle protects the hair and gives it structure and strength. In order to be effective, all texturizing products must penetrate the cuticle in order to reach the cortex.
Located between the cuticle and medulla, the cortex is the thickest layer of the hair shaft. It’s flexible and will return to its original size without adverse effects when stretched. The cortex also contains the hair’s melanin and pheomelanin, which are the color pigments that define hair color.
This inner-most layer of the hair shaft is nearly invisible. It serves as the pith or marrow of the hair and is surrounded by the cortex. It does not play a role in Chemical texture services.
The pH symbol represents potential hydrogen, which indicates the amount of hydrogen ions present in any given solution. A pH scale measures the degree of acidity or alkalinity. The scale ranges from 0 to 14. A pH below 7 is considered acidic, a pH of 7 is considered neutral and a pH above 7 is alkaline.
The natural pH level of hair is between 4.5 and 5.5. Texture services raise the pH of the hair to an alkaline state, which softens and swells the hair shaft. This allows the cuticle layer to open in order for the texture solution to penetrate to the cortex. The more coarse and resistant the hair is, the higher in alkaline the chemical solution must be in order to penetrate the strong and compact cuticle layer.