Several measurement approaches can quantify changing hair properties with sun exposure, which may therefore be used to evaluate productrelated benefits in mitigating such processes. However, such techniques relate to specific and often different portions of hair’s complex structure and may therefore yield differing conclusions. For example, Figure 2 showed the decrease in the wet-state tensile strength of the hair as a function of weathering, a property that is widely-attributed to the integrity of crystalline, alpha-helical keratin microfibrils within cortical cells.