2010 TRI/PRINCETON CONFERENCE 245 parallel to the longitudinal axis of the hair is observed a width of approx. 350 nm (in a range between 200 nm and 500 nm) at the basis of the streaks (black arrows in Figure 8b) is determined by the nanoscope analysis while at their top ends a width of approx. 100 to 200 nm is measured (pink arrows in Figure 8b). The indentations arranged parallel to the longitudinal fi bre axis have depths of approx. 7 nm to 10 nm (green arrows in Figure 8b) as a consequence of the high resolution in this study, smaller cavities of approx. 3 nm depths are observed on top of these striations, some of them round, some more oblong. The phenomenon of longitudinal “striations” has already been described for mammalian hair by J. Smith (17) in 1997 and he assigned this “woodgrain appearance” to exocuticle material exposed after the removal of epicuticle and A-layer due to damaging effects. Later Swift and Smith (7) detected this striation phenomenon on the outer surface of a wide range of mammalian keratin fi bers afore subjected to a thorough cleansing proce- dure by either sonication in sodium dodecyl sulphate or Soxhlet extraction with chloro- form/methanol. They determined the striations “to have a lateral spacing of 350 nm, to be of convex profi le, and rising to a height of approx. 9 nm”. These dimensions fi t very well to those detailed above for the cuticle of bleached hair. The rinse-off treatment of bleached hair with an aqueous solution of 0.15% proteolipid SR changes the surface structure of the damaged hair signifi cantly. Figure 9 shows in direct comparison the SFM images of the virgin hair (a), the ultra bleached hair (b) and the ultra bleached hair treated with an aqueous solution of proteolipid SR (c). In conse- quence of the proteolipid treatment the striations are no longer visible and substituted by patterns which rather resemble the multi layered structures observed for the virgin hair surface (a). EFFECTS OF PROTEOLIPIDS ON THE PHYSICAL PROPERTIES OF THE HAIR SURFACE The effects of proteolipid SR were investigated by means of dynamic contact angle mea- surements according to Wilhelmy on ultra damaged hair. The application of a 0.03% solution of the proteolipid increases the contact angle signifi cantly up to 54°. The effect of hydrophobization increases linearly with the concentration up to a level of 0.15%. At this stage a saturation concentration seems to be reached (Figure 10). Figure 9. SFM image (topography) of a) virgin hair, b) ultra bleached hair, and c) ultra bleached hair treated with an aqueous solution of proteolipid SR (0.15%, m/m).

JOURNAL OF COSMETIC SCIENCE 246 The effect of a rinse-off treatment consisting of an aqueous solution containing 0.15% proteolipid SR strongly depends on the damage degree of the hair surface, as shown in Figure 11. The contact angle of ultra bleached hair increases more than 40% (from 48° to 69°). The surface properties of medium bleached hair do not signifi cantly change and the contact angle of the virgin hair surface slightly decreases. The latter effect may be explained by hydrophobically controlled surface adhesion of proteolipids at the intact hydrophobic hair surface. Investigations by means of the droplet method delivered similar results for the medium bleached hair (II) and the virgin hair. No signifi cant difference between the “pseudo-static” Figure 10. Dynamic contact angles of ultra bleached hair and treated hair with different concentrations of proteolipid SR (*p 0.05. Numbers indicate references for calculation). Figure 11. Dynamic contact angle of ultra bleached, medium bleached and virgin hair before and after treatment with an aqueous solution of proteolipid SR (0.15%, m/m) (*p 0.05 **p 0.01 calculated “untreated” vs. “treated,” respectively).