348 JOURNAL OF COSMETIC SCIENCE MATERIALS AND METHODS MATERIALS Natural hair of Japanese women, 18 cm in length from tip end, was obtained from private source and subjected to measurement of physical properties. The hair was treated with bleaching lotion for 30 minutes at 33°C, rinsed thoroughly in running tap water, and this process was repeated 4 times. After the last bleaching, washing with 15% active sodium laureth sulfate solution, extensive rinsing and drying in a conditioned room (23°C, 40% RH.) followed. METHODS Uptake of amino acid. Japanese hair, treated with a waving lotion of thioglicolic acid and with a neutralizer of sodium bromate, was immersed in a solution of 11.5 mM amino acid. After 10 minutes the concentration of the amino acid solution was determined by HPLC method using an anion-exchange column and an electrochemical detector. Uptake of PCA. Intensively bleached Asian hair swatches, weighing 0.8 g each, were purchased from Beaulax (Tokyo, Japan). Each swatch was washed with a 15 wt% solution of sodium laureth sulfate for one minute, rinsed extensively with running tap water for one minute and air dried. A hair swatch was immersed in 6 ml of amino acid or PCA solution for 30 minutes. The swatch was rinsed in running tap water for 20 seconds and air dried overnight. For recovery of amino acid from the hair, the swatch was immersed in 15 ml of 1 0mM phosphoric acid buffer solution, pH 3.5. After 30 minutes, 10 ml of the buffer solution was removed for quantitative analysis. Concentration of the amino acid or PCA was determined by HPLC method. Hair conditioner treatment and hydrophobicity measurement. Hair conditioner (cationic sur- factant 0.6 wt% active, cetyl alcohol 3.0 wt%, 0.5 g per tress) was applied to wet hair and distributed manually for 30 seconds, then 30 seconds rinsing in running tap water (40°C) followed. The hair tresses were dried for more than four days in a conditioned room (23°C, 40% RH). A hair fiber was fixed in a horizontal position and 1 µl of deionized water was mounted on the point 10 cm from the hair tip end. Twenty seconds later the contact angle which the water drop and the fiber surface form was measured microscopically. Amino acid treatment and tensile strength measurement. A hair swatch was immersed in 100ml of 2 wt% amino acid solution at 35°C for three minutes. The swatch was then rinsed in 100 ml deionized water at 35°C for one minute, and air dried. Tensile measurements were performed on single fibers in deionized water. Hair fibers, 40 mm in length, were immersed in deionized water for at least one hour before the measurement and then extended at a rate of 20mm per minute on a tensile tester KES-G 1-SH (Kato Tech) to obtain force needed to extend the fiber by 20%. Color-retention effect Test I (Figure 1) Extensively bleached Asian hair swatches, purchased from Beaulax, were dyed with

Intensively bleached hair 2006 TRI/PRINCETON CONFERENCE 349 Semi-permanent Dye Dye Color Color measurement measurement 5% PCA Water Wash i\E Figure 1. Experimental design of Test I. 4-amino-3-nitropheol by immersing in the 0.02 wt% solution for 30 minutes. After removal from the dye solution, the swatches were air dried. Treatment with PCA solutions and color measurement: The pH of 5.0 wt% PCA or citric acid solution was adjusted with arginine. A hair swatch was immersed in 6 ml of the solution for 30 minutes. Treatment in deionized water was set as control. The swatch was rinsed in running tap water for 20 seconds and air dried overnight. The color value was measured by a colorimeter (initial value). The swatch was immersed in 6 ml deionized water for 30 minutes, air dried overnight, and the color value was measured again (after wash). Relative BE* was determined as following in order to eliminate the variance among each experiment: Relative .6.E* = LiE*/LiEzonrrnl Test II (Figure 2) • Hair dye: Red shade. The dye component was the emulsion formula based on fatty alcohols and contained following dye precursors and direct dyes Toluene-2,5-diamine sulfate, 2-Methylresorcinol, 4-amino-2-hydroxytoluene, 4-Amino-3-nitrophenol, 6 .. Post-dye Shampoo Shampoo Treatment x3times Conditioner x3times Conditioner Color Shampoo Conditioner Shampoo Color Dye treatment I measurement measurement 'n q A Initial value A A q A q after 6 cycles i::::::: B B B i::::::: B i::::::: i::::::: C C C C i::::::: i::::::: D D D D i::::::: Shampoo Shampoo Conditioner x3 times Conditioner x3times Conditioner Shampoo Conditioner Shampoo Color measurement q A A q A A after 6 cycles i::::::: B B i::::::: B B i::::::: C C i::::::: C C i::::::: D D i::::::: D c:::::: D Figure 2. Experimental design of Test II.