PRACTICAL SELECTING METHOD OF WAVE LOTION FOR HAIR DRESSER 51 Table V. Since it was found that all the virgin hairs show the constant 20% index value in water at 30°C, it is expected that to estimate hair damage (Ero) by measuring only 20% index of the given hairs, if there is a correlation between 20% index and Ero. To determine the effect of perm treatment on the Ero(100%) and 20% index (61.6%) values, Ero(100%) and 20% index (61.6%) for the same virgin hair sample were measured during extensional permanent treatment under three conditions of different virgin hair samples, three types of wave lotions (A–S, A–N, and S–W), and various reduction times. The results are presented in Table VI and Figure 11, which show the plot of the 20% index values against the Ero values. Notably, the 20% index values fell on the line H when the Ero values were above 80%. However, for Ero values less than 80%, the 20% index values for the abruptly in- creased following line L, forming a V shape. As importantly, the graph shown in Figure 11 can be generally applied for anyone whose Fo is unknown. However, it must be noted that this fi gure has a signifi cant weak point, because the H and L lines were obtained with virgin hair that was treated for the fi rst time. Accordingly, these lines cannot be directly applied for hair that has been repeatedly treated, such as is the case for most customers that visit beauty parlors. Therefore, to predict hair damage after repeated permanent treatments, line R was obtained by plotting the 20% index values vs. Ero after repeating the treatment four times (5 min of reduction corresponds to the reduction time of a practical treatment see Practical assessment of wave effi cacy on wave effi cacy) using wave lotions A–S and A–N. Line R shifted to the left of line L by approximately 20%, indicating that severe damage results owing to repetitive treatment. Table VI Experiment for Estimating Hair Damage (Ero) by 20% Index Exp.No Wave lotion Hair Pa(%) Ero (%) 20% Index (%) 0 — Virgin 0 100 61.6 (Av.) 1 A–S Standard 26.5 92.9 59.9 2 A–S School girl-1 31 91.6 59.2 3 A–N School girl-2 40.3 86.7 57.7 4 A–S Standard 61.1 90 57.4 5 A–S Standard 71.2 81.8 56.4 6 C–W School girl-3 84.9 79.2 56.1 7 A–S Standard 77.1 73.1 56.9 8 A–S Standard 80.1 71.5 55.1 9 A–S Standard 87 64.6 58.8 10 A–S Standard 90 50.4 61.2 11 A–S Standard 91.4 49.9 62.9 12 A–S Standard 91.4 39.6 63.6 13 A–S Standard 95.8 30.8 66.6 14 A–S Standard 93.7 28.5 66.3 15 A–S × 4 times Standard 84.5 25.8 63 16 A–N × 4 times Standard 76.6 50.3 57.1 aStandard: donated by beauty parlor “BOY”: school girls (-1, -2, and -3) were picked hairs donated from Tokyo Metropolitan Toyama High school, Tokyo, Japan.

JOURNAL OF COSMETIC SCIENCE 52 Figure 10. Relationship between Pa and hair damage (Ero) (abrupt decrease in Ero). (A) Plot of Pa vs. Ero using the values listed in Table II. The symbols are the same as those in Figure 4. Note: An abrupt decrease in the Ero value is observed at Pa = 80%. (B) Confi rmation of the results shown in (A) using the A–S, A–N, and C–W lotions: ( ), A–S (×), A–N and (▲), C–W. Note: The results shown in (A) are reproducible for the different types of wave lotions from different grade and manufacturers. On the other hand, the shape of the hysteresis curves changed in the order H then L then R, as shown in Figures 12(B), 12(C), and 12(D), respectively. Figure 12(A) shows the hysteresis curve for the virgin hair. The curve for line H marked with an arrow has an obvious shoulder, while that for line L has much less of a shoulder, and that for line R is even smoother. However, although the differences in the curvatures of the curves for L and R appear to be small as observed by the eye, geometric measurement of the curvatures revealed values of 0.76 × 10-2, 7.1 × 10-2, 4.3 × 10-2, and 3.1 × 10-2 for the curves for the virgin hair, and lines H, L, and R, respectively. Accordingly, the use of the graph shown in Figure 11 for estimation of hair damage is limited. The graph can only be directly applied for virgin hair that is to be treated for the fi rst time. To estimate the damage to hair that has received repeated permanent treat- ments, it is possible to approximately estimate the damage to a customer’s hair. If the 20% index value is 61.6% and a line R hysteresis curve is obtained, hard damage (Ero 50%) can be expected. If the 20% index value is 61.6% and a line H hysteresis curve is obtained, then low damage (Ero 80%) can be expected. On the other hand, if the