Chapter 8 261 only a 13% decrease in break stress, fatigue results are indicating differences in the average cycles-to-fail of around an order of magnitude. Thus, findings from fatigue experiments appear more in-line with expectations based on the aforementioned consumer experiences. In addition, one also notices substantially more scatter in the Afro hair results. Many Afro fibers survive for comparable durations to the Caucasian hair however, the overall mean is dragged down by a high number of very early failures. We will return to this occurrence later but, for now, it is sufficient to point out that the considerable difference in the nature of these two plots suggests the presence of different failure mechanisms. In addition to the already fragile state of Afro hair, chemical relaxing (straightening) is a very popular practice as it exposes the wearer to many more style possibilities. These treatments typically involve strongly basic formulations that are known to dramatically further weaken the hair. To illustrate this point, application of a commercial relaxer treatment to our same single-source Afro hair Figure 6. S-N Curves for virgin Caucasian (dark gray data points) and Afro hair (light gray data points) at 60% RH