Curly hair has a number of structural characteristics that are different from straight hair. In response to these specificities, considerably more attention is paid to hair care than to any other part of the body in Africa.
Hair curliness is biologically programmed by the hair follicle and has a number of specificities. First, curly hair follicles sit obliquely in the scalp and are curved at the bulb. The internal structure of the follicle is highly modified, which translates into an elliptical section of the hair, and the development of twists when the hair shaft emerges at the surface of the scalp. Curly hair is also distinguished by the density of its follicles (161/cm²) and its speed of growth (0.85 cm per month) compared to Caucasian hair (226/cm² ; 1.12 cm per month) or Asian hair (175/cm² ; 1.25 cm per month). Also, the average hair diameter is of 78 µm for curly hair, 74 µm for Caucasian hair and 90 µm for Asian hair.
Curly hair's elliptical section and the twists along its fibre make it sensitive to combing and brushing that can cause breakage and limit hair length.
Another specific characteristic of curly hair is dryness due to low sebum production. Sebum scarcity and its limited migration along the hair shaft cause hair dryness and consequently make hairstyling difficult. Furthermore a dry scalp increases irritation and favours dandruff.
In addition to biological characteristics, hairstyling practices also make curly hair fragile. For example, braiding weakens the hair and scalp when braids are too tight; low-quality or poorly rinsed straightening products are damaging, and straightening irons can result in dryness and breakage. Such practices can cause a number of pathologies that include reversible hair-loss, alopecia (hair follicle inflammation being one the first steps of alopecic process) and irreversible scarring alopecia. A number of characteristics that are specific to curly hair therefore need to be taken into consideration in any hair care solution.