JOURNAL OF COSMETIC SCIENCE 534 The lateral areas of CA-permed hair (b) and CYS-permed hair (c) exhibited relatively clear cuticle edges, suggesting that the protease degradation of the cuticle layer is not very much advanced. The degradation of CA-permed hair was a little greater than that of CYS-permed hair. Since the cross sections of CA- and CYS-permed hair were relatively plainer than that of TG-permed hair, the degradation was found to be not very much advanced in the inner part of the hair. As a result, it was found that the surface morphol- ogy of hair after protease treatment refl ects its degradability. CONCLUSIONS The protease degradability of reduced hair and permed hair was related to the reduction power of the mercaptans used on the hair. The degradability increased in the following order: CYS-treated hair CA-treated hair TG-treated hair. In reduced hair, it appears that accessibility may be increased due to the cleavage of di- sulfi de bonds. Therefore, reduced hair became swellable and enzymatic attack was found to increase. As a result, the degradability of reduced hair progresses further. In permed hair, though the cleavage of disulfi de bonds was remarkably small even with repetitive treatment, accessibility is relatively high. Thus the swellability and degradability of re- petitively permed hair appears to progress. Protease degradation is a useful method for evaluating damaged permanent-waved hair. The method is simple, and hair damage can be assessed both visually and through gravimetric analysis. ACKNOWLEDGMENTS We thank Dr. T. J. Lin for his valuable guidance in this research work. Mr. Koji Takano is gratefully acknowledged for his assistance with the SEM procedure. Finally, we would like to express our appreciation to Mr. M. Okano, Mr. T. Yoshida, and Mrs. A. Karasawa, for their discussions and guidance. REFERENCES (1) C. Zviak and A. Sabbagh, “The Science of Hair Care,” in Permanent Waving and Hair Straightening, B. Claude and W. John, Eds. (CRC Press, Boca Raton, FL, 2005), pp. 201–228. Figure 7. SEM photographs of hair after pronase E treatment. (a) TG-permed hair, 3 times. (b) CA-permed hair, 3 times. (c) CYS-permed hair, 3 times. The extent of protease degradation is (a) 19.2%, (b) 16.9%, and (c) 16.2%.

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