PENETRATION OF OILS INTO HAIR FIBERS 295 this work show a complex relationship between capillary liquid films, interfiber capillary adhesion, light reflectance, fiber surface and bulk structure, and molecular diffusion. ACKNOWLEDGMENTS These studies were carried out in conjunction with the TRI project "Analysis and Quantification of Hair Damage," supported by a group of TRI corporate participants. This study was also partially funded by Marico Industries Ltd. We thank Mr. R. B. Mohile for his support. REFERENCES (1) A. S. Rele and R. B. Mobile, Effect of coconut oil on prevention of hair damage Part I,]. Cosmet. Sci., 50, 327 (1999). (2) S. B. Ruetsch, Y. K. Karnath, A. S. Rele, and R. B. Mobile, Secondary ion mass spectrometric inves­ tigation of penetration of coconut and mineral oils into human hair fibers: Relevance to hair damage, ]. Cosmet. Sci., 52, 169 (2001). (3) Y. K. Karnath and H.-D. Weigmann, Measurement of interfiber adhesion,]. Cosmet. Sci., 51, 351 (2000). (4) R. F. Stamm, M. L. Garcia, and J. J. Fuchs, The optical properties of human hair. II. Luster of hair fibers,]. Soc. Cosmet. Chem., 28,601 (1977). (5) A. Guiolet, J.C. Garson, and J. L. Levecque, Study of the properties of human hair, Int.]. Cosmet. Sci., 9, 111 (1987). (6) C. Reich and C. R. Robbins, Light scattering and shine measurement of human hair: A sensitive probe of the hair surface,]. Soc. Cosmet. Chem., 44, 221 (1993). (7) J. H. Brooks, U. K. Das, and L. J. Smith, Effect of lubrication on tensile frictional and weaving properties of sirospun wool yarn, Textile Res.]., 59, 382 (1989). (8) P. N. Moore, S. Puvvada, and D. Blanckschtein, Role of surfactant polar head structure in protein­ surfactant concentration, Langmuir, 19, 1009 (2003). (9) V. Sideris, L.A. Holt, and I. H. Leaver, A microscopical study of the pathway for diffusion of rhodamine B and octadecylrhodamine B into wool fibers,]. Soc. Dyers Colorists, 106, 1 (1990).

]. Cosmet. Sci., 56, 297-309 (September/October 2005) A novel method for visualizing hair lipids at the cell membrane complex: Argon sputter etching/scanning electron microscopy YOSHINORI MASUKA WA, HIROMI SHIMOGAKI, KENJI MANAGO, and GENJI IMOKAW A, Tochigi Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga, Tochigi, 321-3497 (Y.M., H.S., G.I.), and Wakayama Research Laboratories, Kao Corporation, 13 3 4 Minato, Wakayama, Wakayama, 640-8580 (K.M.),Japan. Accepted for publication May 11, 2005. Based on a presentation at the 13th International Hair-Science Symposium, Potsdam, Germany, September 10-12, 2003 Synopsis Hair lipids localized at the cell membrane complex (CMC) play a part in chemical diffusion, cell cohesion, and mechanical strength. There is no method currently available to visualize hair lipids at the CMC. We found that scanning electron microscopy (SEM) of a transversely polished hair plane followed by argon sputter etching (ASE) provides a specific characteristic image consisting of circular patterns (CP) and stitch patterns (SP) at the cortex. Both the CP and the SP are formed as convex structures and are associated with melanin granules and the CMC, respectively. While the convex formation of the CP is not affected by any treatments tested, that of the SP disappeared following treatment of hair fibers with organic solvents and reappeared following incubation of the solvent-treated hair fibers with melting lipids, which suggests that the hair lipids are responsible for the convex SP. Other treatments, such as chemical fixation, thin sectioning, and pre-/post-incubation of the hair plane, reduce or abolish the convex formation of the SP. These findings suggest that the following pathway leads to the convex formation of SP during ASE: (a) joule heat is generated on the surface by violent collisions of argon ions, (b) melting CMC lipids ooze out from the inside to the surface, and (c) CMC lipids that have oozed out are chemically changed, leading to the final convex formation of the SP. With ASE-SEM, visualization of hair lipids as convex structures of SP should enable us to characterize the fine structure and localization of hair lipids and to clarify the roles and functions of the CMC of human hair. INTRODUCTION The cell membrane complex (CMC) consists mainly of proteins and lipids and is dis­ tributed between cortical or cuticle cells of human hair as well as wool (1-3). The CMC Address all correspondence to Genji Imokawa. 297