Chapter 6 213 results are supported by studies that showed that the degree in curl is the predominant factor in reducing combing forces, which in turn can mitigate breakage.40,41 So even though curly hair in its natural untreated state is physically stronger, it does not necessarily reduce breakage during combing compared to straightened hair that has been weakened with a relaxer. Therefore, grooming practices and curl type must be considered when determining appropriate hair care and desired treatments (or lack thereof). Mechanical integrity: It is common knowledge that of the three most commonly studied ethnic groups, hair strength increases for hair types of African, Caucasian and Asian descent (Table 3).42 The fragile behavior of hair of African descent also has been seen in fatigue studies that were conducted by Evans.43 In this test, hair was subject to repeated, relatively low tensile forces and the numbers of cycles that it takes for fibers to break is related to mechanical Figure 8 Example of resulting hair fiber breakage for one out of three hair swatches. Hair was subjected to combing 100 times per day at an average of 1.4 passes/second. Virgin and relaxed hair was lubricated with 0.08 g and 0.05 g of a hair product, respectively. All initial hair swatches were 250 mg in mass and 7 cm in length.