252 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS REFERENCES (1) Blank, I. H., Factors which influence the water content of the stratum corneum, J. Invest. Dermatol., 18, 433-40 (1952). (2) Griee, K., et al., The effect of ambient humidity on transepidermal water loss, Ibid., 58, 343-6 (1972). (3) Wildnauer, R. H., et al., Stratum comeurn biomechanical properties. I. Influence of relative humidity on normal and extracted human stratum comeurn, Ibid., 56,72-8 (1971). (4) Dick, J. C., The tension and resistance to stretching of human skin and other mem- branes, with results from a series of normal and oedematous cases, J. Physiol., 112, 102-13 (1951). (5) Higuchi, T., and Tillman, W. J., Stress-relaxation of stretched callus strips, Arch. Environ. Health, 11, 508-21 (1965). (6) Park, A. C., and Baddiel, C. B., Rheology of stratum comeurn. I. A molecular inter- pretation of the stress-strain curve, J. Soc. Cosmet. Chem., 23, 3-12 (1972). (7) Kligman, A.M., The Biolog[t of the Stratum Comeurn, in Montagna, W., and Lobitz, W. C., The Epidermis, Academic Press, New York, 1964, p. 39 L (8) Wall, R. A., et al., Multiple mechanical relaxation phenomena in human hair, J. Poly- mer Sci., Part C, 14, 299-311 (1966). (9) Ferry, J. C., Viscoelastic Properties of Polymers, John Wiley &, Sons, Inc., New York, 1961, pp. 23, 45-7. (10) Still, J. E., and Cluley, H. J., A new method for the measurement of extremely low humidities and its application to the testing of desiccants, Analy.st, 97, 1-16 (1972). (11) Merck Index, 6th Ed., Rahway, N.J., 1952, p. 1134. (12) Smith, P. R., A New Apparatus for the Study of Moisture Sotption by Starches and Other Foodstuffs in Humidified Atmospheres, in Wexler, A., and wildhack, W. A., Humidity and Moisture, Reinhold Publishing Corp., New York, 1965, pp. 487-94. (13) Kligman, A.M., and Christophers, E., Preparation of isolated slieets •of human stratum comeurn, Arch. Dermatol., 88, 702-5 (1963). (14) Blank, I. H., Further observations on factors which influence, the water content of the stratum corneum, J. Invest. Dermatol., 21, 259-71 (1953). • (15) Goodman, A. B., and Wolf, A. V., Insensible water loss from human skin as a func- tion of ambient vapor concentration, J. Appl. Physiol., 26, 203-7 (1969). (16) Parks, A. C., and Baddiel, C. B., The effect of saturated salt solutions on the elastic properties of stratum corneum, J. Soc. Cosmet. Chem., 23, 471-9 (1972). (17) Singer, E. J., and Vinson, L. J., The water-binding properties of skin, Proc. Sci. Sect. Toilet Goods Ass., 46, 29-33 (1966). (18) Fox, C., et al., Modification of the water holding capacity of callus by pretreatment with additives, J. Soc. Cosmet. Chem., 13, 263-79 (1962). (19) Berube, G. R., et al., Measurement in vivo of transepidermal moisture loss, Ibid., 22, 361-8 (1971). (20) Brubaker, D. W., and Kammermeyer, K., Separation of gases by means of permeable membranes: permeability of plastic membranes to gases, Ind. Eng. Chem., 44, 1465- 74 (1952). (21) Scheuplein, R. J., and Blank, I. H., Permeability of the skin, Physiol. Rev., 51, 702- 47 (1971). (22) Doty, P.M., et al., Water vapor permeability of organic fihns, Ind. Eng. Chem., Anal. Ed., 16, 686-90 (1944). (23) Berube, G. R., and Berdick, M., Transepidermal moisture loss. II. The significance of the nse thickness of topical substances, J. Soc. Cosmet. Chem., accepted for publica- tion.

]. Soc. Cosmet. Chem., 25, 253-262 (May 1974) Skin Moisturizers. II. The Effects of Cosmetic Ingredients on Human Stratum Corneum MARTIN M. RIEGER, Ph.D., and DONALD E. DEEM, M.S.* Synopsis-The four parameters described in Part I of this study, i.e., elastic modulus, re- laxation function, water absorption, and water vapor transmission, have been used to study the effect of typical COSMETIC INGREDIENTS on human STRATUM CORNEUM. The elastic modulus and the stress relaxation modulus are useful measures of the ability of various cosmetic materials to alter the VISCOELASTIC BEHAVIOR of stratum corneum. It has been demonstrated that typical cosmetic HUMECTANTS increase the rate of transepidermal water loss in vitro, and an attempt is made to explain this phenom- enon. INTRODUCTION A variety of humectants and of occlusive lipids has been used for many years to improve human skin and to protect it against damage, even though the principles underlying these approaches to skin treatment were not clearly understood. Blank showed in 1952 how important water is to the well-being of human skin and, in effect, established a rational basis for these time honored methods for skin conditioning ( 1 ). In his very thoughtful review, Chudzikow- ski comments on the undesirability of highly occlusive barriers because they have a tendency to lead to edema he a]so rejects the traditiona] treatment of dry skin with humectants because they will absorb moisture not only from the air but also from the skin (2). It is apparent, therefore, that the cosmetic benefits of either treatment are debatable and that basic knowledge on how skin moisturizers work is lacking. In the first part of this study, in vitro methods for determining the response of human stratum corneum to moisture were developed. It is the purpose of this second part to describe the influence of common cosmetic moisturizers on the properties of stratum comeurn. *Warner-Lambert Research Institute, 170 Tabor Rd., Morris Plains, N.J. 07950. 253