104 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Effect of Cosmetic Treatment/Sequence and Cycles of Chlorination on the Ratio of Knot Breaking-to-Fiber Tenacity (K/T) of Blond Hair Cycles Treatment K/T s* 0 Control 0.600 0.134 Bleach control 0.661 0.055 Dye control 0.630 0.071 Perm control 0. 774 0.077 15 Control 0.924 0.077 Prebleach 0.920 0.118 Post bleach 0.886 0.095 Predye 0.933 0.095 Postdye 0.816 0.045 Preperm 0. 829 0.114 Postperm 0.901 0.089 30 Control 0.955 0.148 Prebleach 0.915 0.096 Postbleach 0.808 0.063 Predye 0.881 0.145 Postdye 0.871 0.055 Preperm 0.955 0.07 ! Postperm 0.844 0.118 * s = standard deviation for eight observations. chlorination. The chlorination procedure was carried out in solutions with 10 ppm chlorine concentration, which is somewhat stronger than typically found in swimming pools. Consequently, the effect of cycles of chlorination seen on the properties examined may be accelerated. The main effect of applying the cosmetic treatment to hair before chlorination was on the wet tensile properties of the fibers. There was a significant decrease in the force required to extend fibers 20% over the decrease given by chlorination alone. The pre- chlorination treatments showed limited effects on interfiber friction, surface mor- phology, weight loss, and knot strength. Postchlorination treatments more greatly affected interfiber friction, cuticular mor- phology, and the weight of the fibers. Both blond and brown hair were affected in a similar manner. The bleaching, dyeing, and perming treatments were strong enough to degrade and remove cuticular material that had been weakened by prior chlorination. This accounted for the smooth appearance of the surfaces, significant weight loss, and, also, the observed decrease in the coefficient of friction of samples chlorinated between 15 and 30 hours. The changes in tensile properties and knot strength were similar to those found with the pretreatments, in spite of greater cuticular damage by posttreat- ment with cosmetic chemicals. REFERENCES (1) N. B. Fair and B. S. Gupta, The chlorine-hair interaction. II. Effect of chlorination at varied pH levels on hair properties,J. Soc. Cosmet. Chem., 38, 371-384 (1987).

THE CHLORINE-HAIR INTERACTION 105 (2) J. Lindberg and N. Gralen, Measurement of friction between single fibers. II. Frictional properties of wool fibers measured by the fiber-twist method, Text. Res. J., 18, 287-301 (1948). (3) G.J. Schuringa, T. Konings, and A. J. Ultee, Jr., Osmotic active substances of the Allw/3rden reaction, Text. Res. J., 23, 645-646 (1953). (4) J. H. Bradbury and J. D. Leeder, Keratin fibers. IV. Mechanism of the Allw/3rden reaction, Aust. J. Biol. Sci., 25, 133-138 (1972). (5) R. Beyak, C. F. Meyer, and G. S. Kass, Elasticity and tensile properties of human hair. I. Single fiber test method, J. Soc. Cosmet. Chem., 20, 615-626 (1969).