J. Soc. Cosmet. Chem., 39, 93-105 (March/April 1988) The chlorine-hair interaction. III. Effect of combining chlorination with cosmetic treatments on hair properties N. B. FAIR and B. S. GUPTA, University of Missouri-Columbia, Columbia, MO 65211 (N.B.F.), and North Carolina State University, Raleigh, NC 27695-8301 (B.S.G.) Received April 23, 1987. Presented in part at the Annual Scientific Meeting of the Society of Cosmetic Chemists, New York, December 1987. Synopsis The results of a study of the combined effect of chlorination and a cosmetic treatment on selected physical properties of human hair fibers are presented. The hair was either bleached, dyed, or permed as a pretreat- ment (before the chlorination procedure) or as a posttreatment (after the chlorination procedure). Cosmetic treatments given as pretreatments did not affect frictional properties and surface morphology as markedly as did the cosmetic treatments given as posttreatments. Bleaching and dyeing produced more pronounced effects on surface properties and weight loss of the hair fibers, while perming had the greater effect on tensile properties. INTRODUCTION In a previous paper (1), we described the results of a study of the effects of chlorine on various hair properties. It is clear, however, that the history of a given human hair may involve many more treatments than chlorination, but little information is available in the published literature on the effects of combining treatments with chlorination on the physical properties of this fiber. This paper reports the results of a study in which each of the treatments of hydrogen peroxide bleaching, oxidative dyeing, and permanent waving were combined with different durations of exposure to dilute concentrations of chlorine. MATERIALS AND METHODS SAMPLE PREPARATION/CHLORINATION PROCEDURE Natural blond and dark brown Caucasian hair purchased from De Meo Brothers Com- pany were used in this study, with samples prepared to suit the physical property being studied (1). Solutions with chlorine concentrations of 10 ppm were prepared by dilution of a sodium hypochlorite solution with deionized water. Two chlorination procedures were used, one for the hair mounted on frames for friction, morphological, and knot strength tests, and the other for hair wound into loops or mounted onto tabs for weight loss or tensile tests, respectively. Treatments were carried 93

94 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS out at room temperature using a ratio of 2000 ml liquor to i g hair. The hair mounted onto frames was subjected to 5, 10, 15, and 30 cycles of chlorination. Each cycle consisted of soaking the hair for one hour in the chlorine solution, rinsing in water, and drying it for 15 minutes in an air-circulating oven at 40-50øC. The samples for weight loss and tensile tests were subjected to 10, 20, and 30 cycles of treatment. Each cycle consisted of soaking the samples for one hour in the chlorine solution. The samples were then transferred to fresh chlorine solution for the next cycle. After each 10 cycles of such treatment, the samples were rinsed in deionized water. COSMETIC TREATMENTS The hair was treated with either a bleach, dye, or perm treatment at one of two stages in the experiment, either as a pretreatment (before the chlorination procedure) or as a posttreatment (after the chlorination procedure). Control samples were subjected only to the chlorination procedure. Bleach treatment. A 3% H202 solution adjusted to pH 9 was prepared by diluting 30% H202 reagent with 0.1 M ammonium hydroxide. The hair was soaked in the bleach solution for one hour at room temperature using a 2000-ml-liquor to 1-g-hair ratio. After soaking, the hair was rinsed in deionized water and air dried. Dye treatment. A commercial oxidative dye (light auburn) was prepared following package directions. The hair samples were placed on polyethylene wrap and completely coated with the dye emulsion (150-ml to 1-g-hair ratio). The hair was treated with the dye for 30 minutes at room temperature, then rinsed with tap water until the water was clear. Immediately thereafter, the hair was soaked in a 5% sodium lauryl sulfate solu- tion for 10 minutes, rinsed with deionized water, and air dried. Perm treatment. A commercial permanent waving treatment (thioglycolate waving lotion and hydrogen peroxide neutralizer) was applied to hair samples lying on polyethylene wrap (150-ml to 1-g-hair ratio). The hair was soaked in the waving lotion for 30 minutes and rinsed with deionized water. The neutralizer was then applied to the hair and left on for 15 minutes. The hair was again rinsed with deionized water and air dried. ANALYSIS OF FIBER PROPERTIES Fiber properties were determined by methods described earlier (1). The twist method of Lindberg and Gralen (2) for measuring friction was used. Parameters examined included coefficient of friction and "percent stick," the percentage of total time involved in the sticking (positive slope) portion of a stick-slip profile. Surface morphology was studied by the examination of fibers in the scanning electron microscope. Changes in the weight of samples were evaluated by determining dry weights before and after treatment. The force and the work required to extend wet fibers 20% of their original length were measured on a constant-rate-of-extension tensile tester using a crosshead speed of 5 mm/min. Fiber tenacity and knot-breaking tenacity were measured on a constant-rate- of-extension tensile tester, using a crosshead speed of 10 mm/min. The ratio of knot- breaking tenacity to fiber tenacity (K/T) was then determined for each hair fiber.