Chapter 8 291 artificial. Nonetheless, if desired, it is possible to perform comparable experiments, with a more realistic tress treatment regimen entwined within the repeated grooming process, to better model real-life conditions. Conclusions In mechanical testing terms, the grooming of hair represents a fatiguing process where individual strands experience repeated exposure to an external stimulus. As such, it appears prudent to study the tendency for breakage under these conditions, with the well-established field of reliability statistics providing guidance. Conceptually, the likelihood of breakage is dependent on both the presence of flaws in hair and their propagation rate. The presence of flaws will be dictated by hair type and condition. As seen here, breakage of Afro hair appears to occur by a distinctly different process to Caucasian hair and involves a considerably higher likelihood of early failure. This would appear to be in-line with frequent presumptions about a kinky hair confirmation yielding a higher number of flaws. Moreover, chemical damage from an aggressive relaxer treatment may also be expected to increase the presence of imperfections and subsequently lead to higher breakage. It is also apparent that flaws may be generated by mechanical means, with habits such as putting hair in a ponytail or braids, or perhaps the use of heat styling appliances, leading to defect formation. It should also be evident that the likelihood of flaws being present will increase with hair length firstly, due to statistical component where a higher probability exists for finding a flaw in a long fiber compared to a short one but additionally, longer hair is older and has undergone more wear and tear. Therefore, there is an inevitable tendency for higher breakage when the wearer adopts longer styles. The rate at which these flaws propagate would seem to depend on the magnitudes of external stimuli. Therefore, it can be seen how higher grooming forces relating to increased surface friction, or indeed higher grooming stresses associated with finer hair, would