Chapter 6 211 hair that is straight. This is due to more inter- and intra-fiber entanglements that are not as prevalent in straight hair. The curl also dictates its behavior in wet versus dry conditions. Hair that is manipulated in environments where the humidity is high tends to be more pliable however, Reutsch and Kamath found that wet conditions can contribute to the hair being more compromised.38 This is due to the swelling of the endocuticle and contributes to a weakened surface where cuticular layers are more susceptible to break-off compared to hair that is dry. Conditioners were found to help mitigate the damage. One must also consider that when curly hair is wet, plasticization along with a decrease in torsion and bending moduli contribute to relaxation of the curl in hair. This, in turn, allows tangles to untwist more readily and as a result, combing forces are decreased compared to dry hair. This is not the case when combing straight hair which is more difficult to comb when it is wet than dry. Straight hair becomes more volumetrically compact when it is wet and the surface tension of water causes the hair fibers to stick to one another. As a result, the adhesive forces due to fiber wetting increase the force to comb down a tress compared to dry hair that has less interaction between the fibers.39 These combing differences are illustrated in Figure 7 and explain the common practice of manipulating curly hair while it is wet to decrease the degree of tangling, which increases manageability and lessens breakage, though gentle handling and conditioners are needed to avoid damage of the cuticle. Relaxer treatments are known to decrease the mechanical integrity of hair (Chapter 5) however, as mentioned above, the combing force of straightened hair can be an order of magnitude lower than that of curly (Figure 7). Even though the majority of women of African descent use relaxers, there is a movement towards donning more natural styles. This is based on the increased quality of natural hair in terms of its mechanical strength. However, there seems to be a curly hair paradox for those who manipulate their natural tresses, which considers the following question: Should natural styles be worn by those who have curly hair because
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