LIGHT SCATTERING IN I IAIR CUTICLES 363 a) c) # Figure 13. Optical and electron microphotographs of fiber surface before and after blow-drying/combing process Optical microscope observations of fiber surlCaces (a) before combing and (b) after combing. (c) SEM observation. The analysis was performed on the same part of the hair fiber. Remnant of endo-cuticle One cuticle layer Figure 14. TEM image of longitudinal section of hair fiber after blow-drying/combing process. a) b) c) Exo-cuticle Figure 15. Schematic diagram illustrating a typical sequence of cuticle damage in which the hair cuticles with glittering speckles are tipped away by combing. (a) After blow-drying. (b) After combing process. (c) Fracturing of cuticle cell by additional combing force. les and the protection effect from cuticle damage. They examined several kinds of materials, including organic solvents, moisturizers, and organic acids, and finally found that treatment with the malic acid (MA)/BOE solution described in the Experimental section, which is also effective for suppression of light scattering from the medulla (1-3), suppresses the generation of glittering speckles (2,3). Figure 16 shows the SEM images of the adjacent parts of the same fiber before and after the treatment with the MA/BOE solution. Through the SEM observations of a longitudinal section, it was confirmed that the cuticle cells swelled from the MA/BOE treatment, and thus the generation of glittering speckles was suppressed by the squeeze of cuticle layers. On the other hand, the analysis by Karl Fischer's method revealed that the moisture content of the hair fiber treated with the MA/BOE solution decreased from its the initial state (Figure 17).

364 JOURNAL OF COSMETIC SCIENCE a) ........... b) .. .. Figure 16. SEM observations of longitudinal and cross sections of hair fibers before (a,c) and after (b,d) MA/BOE treatment. The hair fiber was treated for one hour at 25øC. o a) b) Figure 17. Variation of moisture content in hair fiber (a) before and (b) after MA/BOE treatment. The hair fiber was treated for one hour at 25øC. Furthermore, the amount of agents (MA and BOE) that penetrated the hair was more than 10 wt%. The authors consider that the aqueous molecule is replaced by MA and BOE after the treatment, and that therefore the hair fiber treated with MA/BOE solution prevents the change in moisture content during the blow-drying process.