46 JOURNAL OF COSMETIC SCIENCE CONCLUSIONS 1. The key technology of this study is the formation of a dye-metal ion complex technology that can allow "permanent" acid-type hair color to form on insoluble dye­ metal ion complex in hair but not in the bottle. 2. The performance of "permanent" acid-type hair color, which contains A1Cl 3 ·6H 2 O and glycolic acid, is quite satisfactory as "permanent" hair color. 3. It is proposed that the dye-metal ion complex consists of dye, metal ion, and hair protein. REFERENCES (1) T. Mitsui, Ed. "Hair Color, Hair Bleach," in New Cosmetic Science (Elsevier, Tokyo, 1997), pp. 431-438. (2) Y. Arai, K. Ohno, and U. Tamura, Effect of oils in oxidation hair dye on its dyeing ability. Shikizai., 72, 19-24 (1999). (3) J. Kawase and T. Yoshihar, The trend of development of future problems of semi-permanent hair coloration, Fragrance]., 3, 18-28 (1994). (4) F. Matsuzaki, T. Yanaki, K. Shibata, K. Ohno, H. Nakajima, T. Okuda, M. Yamaguchi, and Y. Kumano, Development of phase-inverting cream hair colorant, 21'' IFSCC International Congress, Berlin, CD-ROM, P3 l (2000). (5) F. E. Wall, "Bleaches, Hair Colorings, and Dye Removers," in Cosmetics Science and Technology, M.S. Balsam and E. Sagarin, Eds. (Wiley-lnterscience, New York, 1997), Vol. 2, pp. 296-343. (6) Y. Nishida, The development of new functional hair colorant, Fragrance]., 5, 29-35 (1998). (7) K.C. Brown, "Hair and Hair Care," in Cosmetic Science and Technology, D. H. Johnson, Eds. (Marcel Dekker, New York, 1997), Series 17, pp. 191-215. (8) M. Oku, H. Nishimura, and H. Kanehisa, The analysis of dissolved proteins from bleached hair,]. Soc. Cosmet. Chem. Japan., 21, 198-209 (1987). (9) Y. Iwamoto, The trend of development and function of temporary hair-coloration and semi-permanent hair-coloration, Fragrance]., 8, 33-39 (2001). (10) Y. Kubo and T. Iijima, Dye elution from aluminum lakes of synthetic food colors (VI), Shikizai., 60, 2-13 (1987). (11) Y. Kubo, M. Shirai, and T. Iijima, Dye elution from aluminum lakes of synthetic food colors (VII), Shikizai., 60, 83-93 (1987). (12) T. Mitsui, Ed. "Hair Color, Hair Bleach," in New Cosmetic Science (Elsevier, Tokyo, 1997), pp. 74-76. (13) M. Ando and T. Matsuo, Recent progress in hair coloring technology-Development of non-odor hair colorants, Fragrance]., 8, 33-39 (2001).

j. Cosmet. Sci.! 56, 47-56 CTanuary/February 2005) A study of the photolightening mechanism of red hair with visible and ultraviolet light: Comparison with blond hair T. TAKAHASHI and K. NAKAMURA, Kao Corporation, Hair-Care Research Laboratories, 1-3, Bunka 2, Surnida-ku, Tokyo1 131-8501 Japan. Accepted for publication December 9, 2004. Synopsis The photolightening behavior of red hair was investigated. Red hair was found to lighten to a similar extent by irradiation from both ultraviolet (UV) and visible (VIS) light. Under the same irradiating conditions, blond hair was lightened by VIS light but did not lighten by UV light until it was washed after irradiation (1). These different photolightening behaviors of rel and blond hair are supposed to be due to differences in their melanin compositions. The dominant type of melanin in red hair is pheomelanin while blond hair investigated in the previous work contained both eumelanin and pheomelanin, with mainly eumelanin (2). Consequently, in this investigation, the photolightening behaviors of red and blond hair were compared to clarify the differences in photosensitivity between the two types of melanin. It has been proven that chemically intact melanin in red hair is considerably more photolabile to UV light than VIS light. Also, it is much more easily decomposed by UV light than melanin granules in blond hair, although they are both similarly decomposed by VIS light. This indicates that pheomelanin is far more sensitive to UV light than eui;nelanin, while these two types of melanin are similarly sensitive to VIS light. This leads to the following hypothetical photolightening mechanism of red hair: When UV light is irradiated on red hair, the light is absorbed by hair protein and attenuated before it reaches the melanin granules. However, since pheomelanin is highly sensitive to UV light, even the attenuated UV light decomposes the pheomelanin to some extent. As a result, UV light lightens red hair without the need for subsequent washing, in contrast to blond hair, which consists of mainly eumelanin. INTRODUCTION It is well known that hair is subject to various influences from sunlight that affect its properties-for example, hair lightening, dryness, split hairs, etc. (3-7). Focusing on hair lightening, which is most noticeable, the photochange of blond hair in the early stages of irradiation was studied and reported previously (1). In that study, the inten­ sities of VIS and UV light were adjusted to represent their proportions in natural sunlight. It was proven that both light sources lighten blond hair, but through different mechanisms, which has led to the following hypothesis: VIS light attacks and decom­ poses melanin granules, which results in the lightening of blond hair. On the other hand, UV light preferentially attacks other hair tissues, causing hair fibers to become damaged 47