Hair Breakage 292 lead to higher breakage. In addition, the deformation induced by these stresses is dependent on the mechanical properties of the hair, which have a high dependence on the environmental conditions. Therefore, at elevated humidity a given grooming stress will lead to greater deformation of the fibers and a faster failure. Of course there is considerable overlap between these two areas where, for example, damaged hair may possess a greater number of flaws, while grooming forces will also be higher. Similarly, higher humidity apparently leads to faster flaw propagation, while increased swelling will yield elevated grooming forces. For this reason, it is useful to have two techniques available to probe the likelihood of hair breakage under these conditions. Single fiber fatigue experiments provide a fundamental understanding of the contribution provided by different variables. Moreover, collected data permits the creation of useful models that allow for predictions as to how the tendency for breakage will change with these conditions. However, we do not know the magnitude of stresses and strains associated with typical grooming practices and so it is not known where real-life conditions sit within this modeling. Instead, repeated grooming experiments allow for extrapolation of these principles into a closer simulation of consumer practices where most usefully perhaps, it is possible to demonstrate and model the considerable benefits of lubricating hair care formulations on the tendency for breakage. This work is ongoing, with the focus being on the interrelated contributions of hair type, hair condition and environmental conditions on the tendency for fiber breakage. Acknowledgements The author would like to acknowledge the contribution of Kimun Park (senior research associate at TRI) for his assistance in both sample preparation and data acquisition. Figures 23 through 29 appear courtesy of the Journal of Cosmetic Science.