154 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table VIII Stiffness of Hair Fibers From Load Extension Experiments Hair Type/Treatment Stiffness I Dry 2 Wet 3 Waller Duncan gm/mm groupings 4 gm/mm Waller Duncan groupings 5 O-SLS 23.1 O-Bleached 22.1 Cau-SLS 18.5 Cau-Bleached 17.8 KI-SLS 14.1 KI- Bleached 12.8 KII-SLS 14.1 KII- Bleached 14.0 13.0 * 11.o [ lO.9 10.3 [ 9.0 8.1 7.9 • Each stiffness number is a mean from 15 fibers. 2 55 to 65% RH. 3 Fibers soaked for 1 hour in tap water, then stretched. 4 Minimum significant difference = 2.92 from Waller Duncan ratio test using Proc ANOVA of SAS Institute (11). 5 Minimum significant difference = 1.31 from Waller Duncan K ratio test. * Significantly different from all other means at the tx = 0.05 level. Table IX Effects of Surface Treatments on Hair Fiber Stiffness gm/mm Extension • Treatment Experiment Calibration Treatment Anacova Result I Dry 2 SAC 2 l. 76 Control 22.76 NSD 21.77 SAC 22.27 II Wet 3 SAC 12.01 Control 13.45 NSD 11.77 SAC 13.53 III Dry Oil 18.09 Control 21.83 NSD 18.02 Oil 21.51 • Each number is a mean from 10 fibers. 2 55 to 65% RH. 3 Fibers soaked in aleionized water 1 hour, then stretched. Between calibration and treatment, fibers were soaked in water 1 hour and allowed to dry overnight before treating and retesting. Table X Dry Fiber Diameters via Linear Density and Microscopy Microns Hair Type/Treatment Linear Density Microscopy O-SLS 86* 89* Cau-SLS 71' 80* KI-SLS 761 84 I KII-SLS 75 84 Differences in diameters indicated by groupings from Waller Duncan K ratio test at o• = 0.05 level. * Significantly different from all other means at tx = 0.05 level.

HAIR ASSEMBLY CHARACTERISTICS 155 Table XI Effect of Bleaching on Dry Fiber Diameter Measured via Microscopy Hair Type/Treatment Microns Unbleached Bleached O-SLS KI - SLS 89 83 90 83 ANOVA: Column effects (treatment): NSD. Row effects (hair type): Significant. Interactions: NSD. An alternative explanation may be associated with our calibration standards for the microscopic method. As indicated in the experimental section, stainless steel surgical suture wire of known diameter [provided by the supplier (7)] was the calibration stan- dard, and the diameters of the wire standards were checked with a micrometer. Regression analysis shows a significant relationship between fiber diameters by these two methods, with an index of determination of 0.96, suggesting that either method is a satisfactory predictor of the other for the hair used in this study. Hair of high ellipticity was not used, and each microscopic diameter in this table is an average of 50 measurements made at random, not maximum and minimum diameters, thus providing an estimate of "average" diameter. The effects of hair bleaching on dry diameter were evaluated on O and KI hair samples and the results are summarized in Table XI. These data show no significant effect of bleaching on dry fiber diameter (--60% RH) under these conditions. Although hair types were significantly different, the lack of significant interactions indicates that the bleach effect is the same for both hair types. Therefore the bleaching conditions of this study are assumed to have no effect on dry fiber diameter for all four hair types. Wet diameters were estimated from percent weight gains determined by the centrifuga- tion method (20), in the following manner. Percent weight gains of human hair vs relative humidity (21) correlate with, and therefore can be used to predict, percent volume increase (9) by moisture adsorption. Therefore the percent weight gains of Table XII were assumed to equal the percent volume increase from zero to 100 percent RH. Table XII Wet Fiber Diameters via Centrifugation Method Hair Type/Treatment % Weight Gain Calc. Diameter KI- Bleached 47.5 * 87 KI- SLS 46.2 I 86 KI- SAC 46.0 86 O-Bleached 39.6 I 95 O-SLS 38.4 94 Cau-Bleached 36.2 I 77 Cau- SLS 35.6 77 Differences in weight gains indicated by groupings from Waller Duncan K ratio test at o• = 0.05 level. * Significantly different from all other means at o• = 0.05 level.