EFFECTS OF CHLORINE ON HAIR 235 WITH SCALES AGAINST SCALES PPM 0.:36 50 io 0.:32 0.28 0.24 - 0 (CONTROL) 0.20 I I I I I 20 40 60 20 40 NUMBER OF CYCLES Figure 3. Effect of chlorination at pH 8 on average coefficient of friction. PPM ., - I0 ONTROL) I 60 number of cycles of treatment can be more clearly examined from the curves in Figure 3. The greatest increase in the values of coefiqcient of friction of the chlorinated samples has occurred by 20 cycles of treatment. Further increases in cycles do not produce significant change. These results, thus, indicate that a mild chlorination treatment, as might be experienced in swimming, can have a marked effect on frictional properties of hair. Comparing the results of the two different directions of rubbing, i.e., the "with" scale and the "against" scale of the chlorinated samples, it is seen that in general the changes in the "with" scale are greater than those in the "against" scale. A consequence of this is WITH SCALE, 10 PPM Figure 4. Effect of chlorination at pH 8 on Instron © force pattern during friction tests.

236 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS a reduction in the value of DFE as seen in Table II. The effect of the number of cycles on DFE is small and irregular. The control samples show a different trend. While there is a continual increase in the values of coefficient of friction, the "against" scale values increase more than the "with" scale, resulting in an increase in DFE with cycles. Repeated expansion and contraction of fibers during the soaking and drying of each cycle could be making the .., Figure ga. Control, 60 cycles of treatment at 0 ppm and pH 8, showing "against" scale rubbing. Figure 5b. 20 cycles of chlorination at 10 ppm and pH 8, showing "with" scale rubbing. ', ,• 'r•-." • 77, e,. ..% - • ,•"• . '.--,.-.[ . . %, Figure 5c. 60 cycles of chlorination at 10 ppm and Figure 5d. 20 cycles of chlorination at 50 ppm and pH 8, showing "with" scale rubbing. pH 8, showing "with" scale rubbing.