When the surfaces were exposed to water, the free fatty acids assist in formation of domains, reducing the exposed surface area of the protein (Supplementary Figure ). This behavior is also reflected in the shift towards untilted 18-MEA on the surface (Figure ). In the case of dry surfaces with free fatty acids present, 18-MEA tilt angles were lower, but not significantly different from 18-MEA alone.In the case of free fatty acids and water present at the surface, this was not the case. Water is able to drive the tilt angles to adopt a more broad distribution, with a peak near 40 degrees for the virgin hair surface. The resulting tilt angle distribution is closer to those observed in densely packed monolayers of 18-MEA . This result suggests that fatty acids, either deposited or endogenous, are able to create a densely packed hydrophobic surface with similar organization of a langmuir monolayer of 18-MEA. The more broad distribution of tilt angles for the lightly and moderately damaged surfaces also explains the loss of the advantageous characteristics of hair surfaces. This conclusion is supported by work done by Bergendal, who studied isotherms of 18-MEA, palmitic, and stearic acid on neat water subphases and deposited on silicon wafers . They observed that compared to 18-MEA alone, the addition of free fatty acids in isotherms results in a large range in average area per molecule. The author concluded the flexibility in local fatty acid rearrangement makes for more effective surface coverage of the hair surface. Our models compliment these observations, and provide atomic level resolution of the behavior.