278 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ACKNOWLEDGMENTS We wish to thank Mr. Andrew Charig, who synthesized most of the radiolabeled materials used in this work. We wish also to thank Ms. Donna Hartnett, who synthe- sized [35SISDES-3. The bulk of the tress studies were performed by Ms. Donna Hartnett and Ms. Judy McKendrick. Ms. Hartnett and Ms. Lois Castrovince performed most of the radiotracer measurements. We are grateful to Mr. Frank Schebece for valuable discussions. REFERENCES (1) C. Reich and C. R. Robbins, Light-scattering and shine measurements of human hair: A sensitive probe of the hair surface, J. Sac. Cosmet. Chem., 44, 221-234 (1993). (2) C. Robbins, C. Reich, and J. Clarke, Dyestaining and the removal of cationics from keratin: The structure and the influence of the washing anion, J. Sac. Cosmet. Chem., 40, 205-214 (1989). (3) R. F. Stamm, M. L. Garcia, and J. J. Fuchs, The optical properties of human hair. I. Fundamental considerations and goniophotometer curves, J. Sac. Cosmet. Chem., 28, 571-599 (1977). (4) B. J. Tighe, "Subjective and Objective Assessment of Surfaces," in Polymer Surfaces, D. T. Clark and W. J. Feast, Eds. (John Wiley & Sons, Chichester, 1978), pp. 269-286. (5) D. B. Judd and G. Wyszecki, Color in Business, Science, and Industry, 2nd ed. (John Wiley & Sons, New York, 1963), p. 381. (6) C. Reich and R. Heck, unpublished results.

j. Soc. Cosmet. Chem., 44, 279-288 (September/October 1993) Flygroscopicity and water-holding capacity of moisturizing agents: A single-application in vivo study JIROT SINDHVANANDA, PIMOLPUN GRITIYARANGSAN, PRAWIT RUNGRAIRATANAROIJ, and PREYA KULLAVANIJAYA, Institute of Dermatology, 420/7 Rajavithi Road, Phrayathai, Bangkok 10400, Thailand. Received November 18, 1992. Synopsis A comparative study of four kinds of moisturizers for their hygroscopicity and water-holding capacities as measured by a skin surface hygrometer showed that all agents could improve the water content of the skin surface. The most effective agent was Eucerit, a lanolin alcohol-containing agent, and the second was a urea-containing agent. The Eucerit-containing agent also showed high stability accoMing to the water- holding capacity patterns observed after five minutes and three hours. INTRODUCTION The water content of the stratum corneum plays an important role in providing the skin surface with suppleness, good function, pliability, and smoothness (1). This thin layer serves as a protective sheath that protects the body from the invasion of various kinds of external attacks (2) such as living organisms, chemical agents, and physical factors. There is a big difference between the moist and humid environment beneath the stratum corneum and the dry atmosphere outside the body, and the stratum corneum is the only layer between them. In vitro studies on stratum corneum showed that it is flexible as long as it contains more than 10% water (3). The water-holding property of the stratum corneum is influenced by water-soluble materials, such as free amino acids, organic acids, urea, and inorganic ions (4). Lipids in the lamellar structure in the intercellular spaces of the stratum corneum also play a part in water-holding (5,6). Smooth and soft skin is not only good-looking but is also healthy. On the other hand, dry, scaly, or rough skin shows an unhealthy condition or underlying disease (7) and reflects low water content in the stratum corneum (3). People accept these concepts and try to use agents to improve water content and smooth their skin. There are many agents on the market that claim to smooth the skin and hold water on the skin surface. A variety of techniques for assessing skin hydration have been developed and reviewed (7-11). Most in vivo techniques are based on electrical measurements such as resistance, capacitance, impedance and, conductance. We try to evaluate the moisturizing agents 279