102 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table III Effect of Cosmetic Treatment/Sequence and Cycles of Chlorination on the Weight Loss of Blond Hair Cycles Treatment % Wt loss s* n** 0 Bleach control 0.8 0.33 6 Dye control 0.4 0.3 ! 6 Perm control 0. ! 0.15 4 !0 Control 0.7 0.45 5 Prebleach 1.5 0.22 5 Postbleach 4.4 0.44 5 Predye 1.4 0.43 6 Postdye 1.7 0.55 6 Preperm 0.4 0.48 5 Postperm 0.2 0.40 5 20 30 Control Prebleach Postbleach Predye Postdye Preperm Postperm Control Prebleach Postbleach Predye Postdye Preperm Postperm 1.6 O.6O 5 !.8 O.38 5 8.7 0.89 5 !.9 O.45 6 5.6 1.80 6 0.4 0.27 5 1.8 0.48 6 3.5 1.10 5 3.3 O.75 5 12.6 1.61 5 3.5 O.84 6 8.7 1.50 6 1.2 0.32 5 4.8 1.14 6 * s = standard deviation. ** n = number of observations. significantly different from those of the other treatments by 20 hours of chlorination. The rates of weight loss of the postdyed and postbleached samples were also much greater than those of the others. These results correlate well with the loss of surface material noted in SEM analysis. The weight loss of the dyed samples was somewhat less than expected from the SEM results. The deposition of dye molecules into the fiber may compensate for some of the lost cuticular material. These results suggest that as chlo- rination proceeded, an increasing amount of cuticular material became detached from the substructure and remained held to the fiber by the cell membrane. If the bleach and the dye treatments degraded the cuticle cell membrane, the detached cuticular material could be lost quite readily. Values of the reduction in the force and the work required to extend wet fibers 20% are given in Table IV. The cosmetic treatments alone caused significant reductions. There was no significant difference between the effects of the bleach and the dye treatments. The perm treatment, however, caused a significantly greater reduction than the other two. Beyak et al. (5) found similar results (30% reduction in force for 15% elongation) in a permanent wave treatment of hair involving a ten-minute reducing step and a five-minute neutralizing step. Such a large change in force and work with perming

THE CHLORINE-HAIR INTERACTION 103 Table IV Effect of Cosmetic Treatment/Sequence and Cycles of Chlorination on the Percent Reduction in Force and Work Required for 20% Extension of Blond Hair Cycles Treatment Force s* n** Work s n 0 Bleach control 7.48 1.14 9 13.02 2.93 8 Dye control 6.41 1.5 ! 7 9.89 3. !2 7 Perm control 43.82 3.40 6 51.54 5.79 6 10 Control 4.03 1.34 11 8.00 3.03 8 Prebleach 14.15 3.42 14 17.50 5.43 14 Postbleach 11.91 2.07 8 17.02 4.60 10 Predye 19.79 4.51 10 24.57 6.02 10 Postdye 12.51 1.94 8 11.96 2.87 7 Preperm 50.93 6.77 10 60.12 6.17 12 Postperm 49.58 4.99 10 54.51 4.46 10 20 Control 7.76 1.61 11 13.35 3.78 8 Prebleach 20.77 2.96 14 24.56 3.93 14 Postbleach 20.77 2.96 9 24.55 4.14 10 Predye 25.17 3.5 ! 10 26.93 5.20 10 Postdye 22.96 4.27 9 21.64 5.44 9 Preperm 58.29 5.58 10 64.56 4.60 ! 2 Postperm 59.86 3.47 8 61.62 5.28 9 30 Control 19. !9 1.75 11 21.62 3.58 8 Prebleach 27.67 2.86 14 32.24 4.28 14 Postbleach 30.26 4.34 7 36.05 4.30 7 Predye 33.83 3.07 10 36.89 3.64 !0 Postdye 31.89 3.99 8 35.48 7.27 10 Preperm 62.50 5.15 10 69.26 4.92 !2 Postperm 65.72 4.32 8 68.14 4.20 8 * s = standard deviation. ** n = number of observations. could be due to the incomplete reformation of disulfide crosslinks. The effect of com- bining the cosmetic treatments with chlorination appeared to be additive. The effect of treatment sequence for each cosmetic treatment, however, was not significant, sug- gesting that both treatment sequences affected the cortex of the fiber to a similar ex- tent. Therefore, the cuticle did not contribute significantly to the tensile properties of wet hair fibers at low extensions (20%). Values of the ratio of knot breaking-to-fiber tenacity are given in Table V. Only perming caused a significant increase in K/T in the control samples. Analysis of vari- ance indicated no significant effect of treatment sequence on the values of this param- eter. All treatments produced a similar significant increase in K/T when cycles of chlo- rination increased from 0 to 15, with no further significant change occurring beyond 15 cycles. These results are similar to those seen in the study of the effect of pH (1). Once again, the results indicated that the treated fibers were more flexible. CONCLUSIONS Two distinct trends were seen when chlorination was combined with cosmetic treat- ments, depending upon whether the treatment was applied to the hair before or after