38 A1Cl3 ·6H2O ZnC1 2 FeCl2 ·4H2O CaC12 ·2H2O MgC12 ·6H2O CuSO4·5H2O FeSO4·7H2O BaCl2 ·2H 2 O MnC12 ·4H 2 O NaCl KCl Control JOURNAL OF COSMETIC SCIENCE Table VI Longevity Due to Dye-Metal Ion Complex Color longevity effect (%) 91.47 77.65 71.93 78.19 76.54 81.87 74.88 77.26 77.28 63.53 75.04 74.05 The color longevity effect is represented by the following formula: Color longevity effect = Lldycd h ajLlEwashed ha ir x 100 Error range (mean +/- S.D.) 89.84-93.10 74.07-81.23 65.82-78.04 71.26-85.12 74.11-78.97 79.03-84.71 72.84-76.92 7 4.19-80.33 74.94-79.62 60.08-66.98 67 .05-83.03 69.73-78.37 where LlEdyed h air and LlEwashed hair are the degree of color change after dyeing and washing. The range was calculated by using the mean value and the standard deviation (S.D.). The result indicates that certain metal ions affect longevity at pH 3.0. AlC13 ·6H2O was substantially superior to the other metal ions in producing a longer-lasting hair color. 40 35 w 30 25 20 0 0.4 0.8 1.2 1.6 Concentration of AICl3·6H2O (%) Figure 4. The optimal concentration of AlCL, ·6H2O was investigated at pH 3.0. The closed circle (e) indicates the degree of color change (LlE) of the dyed tress (n=3). Figure 6 shows the result of (A) red fashion color and (B) brown-for-gray coverage. Both Figure 6A and 6B show that the color brightness and the color longevity effect of the "permanent" acid-type hair color were improvements over those of conventional acid­ type hair color. Figure 6A shows that the color brightness effect of conventional acid­ type hair color with this dye formulation was originally better than that of the conven-

NOVEL ACID-TYPE HAIR COLOR TECHNOLOGY 39 "Permanent " acid-type Conventional acid-type Figure 5. Microscopic observation of a cross section of human hair dyed with the "permanent" acid-type and a conventional acid-type hair color. Both hair colors contained acid orange 7 (0.44%) and acid red 52 (0.15%). The "permanent" acid-type contained 0.5% A1Cl3 ·6H2O and 1.6% glycolic acid. 110 110 (A) Red fashion Shade (8) Brown for gray coverage � 100 -�- ■ -100 �� � 0 0 �- ' � I � ♦ C � C 90 C 90 � ·a, ·a, C ♦ C cu I cu .c .c 1.- 0 - 0 �� 0 80 0 80 u u :l 70 70 0 2 4 6 0 2 4 6 Times of wash Times of wash Figure 6. Color brightness and color longevity effect of (A) red fashion shade and (B) brown-for-gray coverage on Asian white hair. The closed square (■), diamond ( ♦ ), and triangle (.&) represent the color-changing ratio of "permanent" acid-type, conventional oxidative, and conventional acid-type hair colors, respectively. The color-changing ratio was evaluated by the following equation: Color changing ratio (%) = [dEwashec.l hai,} / [dEdyed hai,} x 100 where dEdyed hair and dEwashed hair represent dE immediately after dyeing and washing, respectively. In (A), the color brightness effect, which is represented by dEdyed hair' of novel acid-type, conventional oxidative, and conventional acid type, is 57.80, 31.35, and 48.44, respectively. In (B), the color brightness effect, which is represented by dEc.1yed hair• of novel acid-type, conventional oxidative, and conventional acid type is 44.52, 44.61 and 39.77, respectively.