SILICONES ON HAIR 245 ACKNOWLEDGMENTS The authors are grateful to the following for their assistance: J. Grande, who supplied image analysis and microscopic data, D. Anderson for AA work, and R. Bolon for SEM micrographs. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) P. Berth and G. Reese, Alteration of hair keratin by cosmetic processing and natural environmental influences, J. Soc. Cosmet. Chem., 15, 650-666 (1964). L. J. Wolfram and M. Lennhoff, The effect of chemical treatment on the tensile properties of keratin fibers, J. Text. Inst. Trans., 57(12), T590-591 (1966). R. Beyak and C. F. Meyer, Elasticity and tensile properties of human hair. II. Light radiation effects, J. Soc. Cosmet. Chem., 22, 667-678 (1971). L. J. Wolfram, "The Reactivity of Human Hair, a Review," in Hair Research, Orfanos, Montagna, Stuttgen, Eds. (Springer-Verlag, Berlin, Heidelberg, 1981). M. L. Garcia, J. A. Epps, and R. S. Yare, Normal cuticle-wear patterns in human hair,J. Soc. Cosmet. Chem., 29, 155-175 (1978). C. R. Robbins and M. K. Bahl, Analysis of hair by electron spectroscopy for chemical analysis,.J. Soc. Cosmet. Chem., 35, 379-390 (1984). B. Thompson, J. Vincent, and D. Halloran, Anhydrous hair conditioners, silicone-in-silicone delivery systems, Soap Cosmet. Chem. Specialities, 25-28 (October 1992). E. G. Gooch and G. S. Kohl, Method to determine silicones on human hair by atomic absorption spectroscopy,.J. Soc. Cosmet. Chem., 39, 383-392 (1988). J. Jachowicz and M.D. Berthiaume, Heterocoagulation of silicon emulsions on keratin fibers, .J. Colloid lnterfaceSci., 133, 118-134 (1989). M. D. Berthiaume and J. Jachowicz, The effect of emulsifiers and oil viscosity on deposition of nonionic silicone oils from oil-in-water emulsions onto keratin fibers, J. Colloid Interface Sci., 141, 299-315 (1991). B. K. Thayer and J. H. Merrifield, Novel Amino Functional Sdicone Polymers for Improved Hair Condi- tioning, presented at the XVI IFSCC Congress, New York, October 1990. J. H. Merrifield, R. J. Thimineur, and F. J. Traver, US Patent 5,244,598. J. H. Merrifield and D. A. DeLuke, Silicones in Hair Conditioners.' Factors Controlling Hair Deposition, presented at the 202nd ACS National Meeting, New York, August 1991. J. Jachowicz and M. D. Berthiaume, Microemulsions vs. macroemulsions in hair care products, Cosmet. Todetr., 108, 65-72 (1993). P. Alexander and J. T. Lett, "Effects of Ionizing Radiation on Biological Macromolecules," in Comprehensive Biochemistry, Vol. 27: Photobiology, Ionizing Radiation, M. Florkin and E. H. Slotz, Eds. (American Elsevier, New York, 1967), pp. 267-356.

j. Soc. Cosmet. Chem., 46, 247-254 (September/October 1995) Influence of emulsions with and without urea on water-binding capacity of the stratum corneum j. BETTINGER, M. GLOOR, W. GEHRING, and W. WOLF, Dermatological Department of the Clinical Centre of the City of Karlsruhe (J. B., M.G., W.G. ) and Federal Research Centre of Nutrition, Institute of Process Engineering (W. W. ), Karlsruhe, Germany. Synopsis This study was undertaken to delineate the effects of emulsions with and without urea on the water-binding behavior of the stratum corneum at different relative humidities (RH). The heels of 54 human volunteers were treated with water-in-oil (w/o), and oil-in-water (o/w) emulsions with and without urea (urea content 10%). After treatment the water content was determined by measuring the weight of the callus. The results show that urea increases the amount of free water at high RH. Both types of emulsions led to a significant reduction in the water content of the stratum corneum at 60%-70% RH, suggesting an effect on the secondary, weakly bound water. INTRODUCTION The water content of the stratum corneum is increased by urea-containing preparations (1,2) applied to skin. In addition, the water-binding capacity of the stratum corneum can be assumed to be affected by the emulsifiers in these preparations. This is because emulsifiers have been shown to become incorporated into the lameliar structures of the intercellular lipids (3), which participate in the water-binding process of the stratum corneum (4,5). Furthermore, the tenside properties of emulsifiers can lead to changes in the amount and composition of the intercellular lipids (6-8). The present study delin- eates the effects of urea and emulsifiers on the water content of stratum corneum (callus). MATERIALS AND METHODS TEST SUBJECTS AND TREATMENT Fifty-four volunteers were selected who were free of severe diseases, showed no patho- logical findings on the soles of the feet, and had not undergone any local treatment for the previous two weeks. Their informed consent was obtained. The subjects included 37 women and 17 men, of ages between 15 and 89 (48.8 + 20.5). They were divided randomly into four groups: 247