NOVEL ACID-TYPE HAIR COLOR TECHNOLOGY 33 was embedded in polyvinyl alcohol gel (Tissue-Tek®, Sakura Finetechnical, Tokyo), which was cooled and solidified. The solidified sample was sliced to a thickness of 5 µm by a microtome (Microtome CM3050, Leika, Postfach, Germany). The cross sections were observed by a microscope (VH-2450, Keyence, Osaka). VERIFICATION OF THE FORMATION OF DYE-METAL ION COMPLEX The key technology of formation of a dye-metal ion complex inside the hair was verified by an EDTA extraction study. The hair colorant of Sample C in Table I was prepared. Tresses of human hair were dyed with the hair color at 30 °C for 30 min. The dyed tresses (1.5 g) were dipped in 100 ml of 0% to 2% of EDTA·2Na water solution. After the tresses were washed in an ultrasonic bath (W-21 OR, Honda Electronics, Aichi, Japan) for 30 min, the outer solution was collected and filtrated through a filter paper. The UV spectrum of the solution was measured by a spectrophotometer (V-550, J asco, Tokyo). FLUORESCENT X-RAY ANALYSIS OF THE STATE OF THE ALUMINUM ION OF DYE-METAL COMPLEX To obtain the complex of A1Cl 3 ·6H 2 0, hair protein (this tress sample was called Al-Hair) and acid orange 7 (Al-Hair-Dye), the tresses (2 g) were dipped in the sample (100 ml) in Table II for 30 min. After being rinsed with water, the tresses were air-dried. This process was repeated three times. To obtain the complex of A1Cl 3 ·6H20 and acid orange 7 (Al-Dye), 0.5% A1Cl 3 ·6H20 was added to 1 % acid orange 7 solution. A deposit, which was considered to be a complex of aluminum chloride and acid orange 7 appeared in the mixed solution. The deposit was collected and dried. To analyze the state of the aluminum ion of the samples, the K 13 spectrum of the aluminum ion (Al-K 13 ) was measured by a fluorescent X-ray analyzer (Philips PW2400, Eindhoven, Netherlands). The measurement was performed under these conditions: analyzing crystal, PET voltage, 24 kV current, 125 mA scanning angle (20), 128.5°- 137.50 . NMR ANALYSIS OF THE STATE OF BOND The complex of aluminum ion and acid orange 7 (Al-Dye) obtained as described above was analyzed by NMR. Proton NMR spectra were recorded at 400.13 MHz, without spinning, on an ECP-400 spectrometer CTeol, Tokyo). The solvent used in the measure- Table II Formulation of Experimental Samples (w/w % ) Al-Hair* Al-Dye Al-Hair-Dye Benzyl alcohol 8 8 Ethyl alcohol 20 20 A1Cl 3 ·6H20 0.5 0.5 0.5 Acid orange 7 Ion-exchanged water Up to 100 Up to 100 Up to 100 * Al-Hair, Al-Dye, and Al-Hair-Dye represents complex of AlCL3 ·6H 2 0 with hair protein A1Cl3 ·6H20 and acid orange 7 and A1Cl3 ·6H20, hair protein, and acid orange 7, respectively.

34 JOURNAL OF COSMETIC SCIENCE ment was CD 3 OD at 30°C. AL-Dye (10 mg) was dissolved in CD 3 OD (1 ml) and the supernatant was collected (Al-Dye/CD 3 OD). After the NMR spectrum of Al-Dye/ CD 3 OD was obtained, a few drops of 0.1 % EDTA in CD 3 OD was added to the NMR sample. The mixed solution was called Al-Dye-EDTA/CD 3 OD. SENSORY EVALUATION The obtained novel acid hair color was evaluated by 34 panelists (females, ages 21-57 years). Ten panelists were regular users of a conventional acid-type hair color for gray coverage (Test 1), seven panelists were regular users of a conventional oxidative hair color for gray coverage (Test 2), and 1 7 panelists were regular users of a conventional oxidative hair color for fashion shade (Test 3). The panelists compared a novel acid-type hair color with a conventional hair color that they regularly used. The evaluation result of the novel acid-type hair color was obtained by interviewing the panelists. To test various colors, the dye formulation of the novel acid-type hair color of Sample C in Table I was changed. The most popular brown shade on the market was used for Test 1 and Test 2, and the most popular orange, yellow, and ash (blue black) shades on the market for Test 3. RESULTS SELECTION OF ACIDS Added to the hair colorant of Sample Bin Table I was 1.6% of formic acid, glycolic acid, lactic acid, acetic acid, tertronic acid, or glycine hydrochloride. The color brightness and color longevity of the additional acid were investigated (Table III). In these acids, glycolic acid was chosen as the most preferable acid that can provide color brightness and color longevity effects because formic acid is undesirable in terms of its smell and safety. Formic acid Glycolic acid Lactic acid Acetic acid Glycine hydrochloride Tretronic acid Table III Characteristics of Acids Color brightness effect 55.808 55.863 54.942 53.813 54.53 53.783 Error range (mean +/- S.D.) 55.275-56.340 55.239-56.486 54.634-55.250 53.479-54.148 54.294-54.767 53.522-54.043 Color longevity effect(%) 90.519 96.562 94.816 95.111 94.011 93.593 Error range (mean +/- S.D.) 90.166-90.871 95.658-97.467 94.109-95.523 94.298-95 .923 93.329-94.693 93.081-94.104 The color brightness effect is expressed by 8-Elycl ha ir• The color longevity effect is represented by the following formula: Color longevity effect = 8-Ewashed ha j 8-Edyed ha ir x 100 where 8-Edyed hair and 8-Ewashed ha ir are the degree of color change after dyeing and washing. The error range was calculated by using the mean value and the standard deviation (S.D.). The Hunter Lab system was applied for calculating the 8-E values. The 8-E values, which express the strength of the color, is expressed by the following formulas: 8-Edyed = ✓ (Ldyed - La) 2 + (a dyed - ao) 2 + (b dyed - bo) 2 8-Ewashed = ✓ (Lwa.rhed - Lo) 2 + (awashed - ao) 2 + (bwashed - bo) 2 Ldyed : L value after dyeing. adyed : a value after dyeing. bdyed : b value after dyeing. Lwashed : L value after washing. awashed -' a value after washing. bwashed : b value after washing. L0: L value of tress. a0: a value of tress. b0: b value of tress.