Despite a higher surface density of total fatty acids, water was able to penetrate the outer surface into the protein layer on the timescale of the simulations. For the case of virgin hair plus free fatty acids, water penetration was not able to reach the center of the KAP5-1 bilayer in our lengthy computational time (1 μs) whereas water is present throughout the entire protein layer in the highly damaged hair model (Figure ). This corroborates previous experimental observations that water penetration is dependent on the amount of 18-MEA removed from the surface, but a non-trivial amount of water is able to penetrate even virgin hair surfaces . However, these trends in observed kinetic behavior do not necessarily translate to thermodynamic stability ranking. We postulate that additional computational studies using stochastic sampling techniques such as Grand Canonical Monte Carlo simulations may help further support our observations.