Hair Care - DermaAmin

Hair physiology 11
Figure 1.13
African-American hair shaft shape.
water content and, most importantly, a flattened elliptical cross-sectional shape 39 (Figure
1.13). It is the asymmetry of this cross-section that accounts for the irregular kinky
appearance of Black hair 40 (Figure 1.14). Hair that is wavy or loosely kinked has a crosssectional
shape in between a circle and flattened ellipse (Figure 1.15).
The cross-sectional shape of the hair fiber accounts for more than the degree of curl, it
also determines the amount of shine and the ability of sebum to coat the hair shaft. 41
Straight hair possesses more shine than kinky hair due to its smooth surface, allowing
maximum light reflection and ease of sebum movement from the scalp down the hair
shaft (Figure 1.16). The irregularly kinked hair shafts appear duller, even though they
may have an intact cuticle, due to rough surface and difficulty encountered in sebum
transport from the scalp, even though Black hair tends to produce more sebum (Figure
1.17).
The shape of the hair shaft also determines grooming ease. Straight hair is the easiest
to groom, since combing friction is