TRANSEPIDERMAL WATER LOSS 343 (17) R. M. Handjani, B. Rondot and F. Lachampt, Perspiratio insensibilis controled by specific associations of lipids. Cosmet. Perf., 90, 39-41, 1975. (18) R. M. Handjani, B. Rondot and F. Lachampt, Measurements of the moisturizing effect, Cosmet. Toiletries, 91, 25-30, 1976. (19) J. D. Middleton, The mechanism of action of sufactants on the water binding properties of isolated stratum corneum,J. Soc. Cosmet. Chem., 20, 399-412, 1969.

j. $oc. Cosmet. Chem., 30, 345-356 (November 1979) Study on the occlusivity of oil films HISAO TSUTSUMI, TOSHIAKI UTSUGI and SHIZUO HAYASHI Kao Soap Co., Ltd., Tokyo Research Laboratories, 2-1-3 Bunka, Sumida-ku, Tokyo 131, Japan. Received January 18, 1979. Presented IOth I.F.S.C.C. Congress, October 1978, Sydney, Australia. Synopsis The OCCLUSIVITY of oils was determined in vivo by measuring the suppression of transepidermal water loss (TEWL) of the skin. Various emollients were applied to human skin in various forms, including powder, solution and emulsion of different types having different size distributions, and the residual states of the OIL FILMS on the skin surface were examined with time. In order to discuss the occlusivity in relation to the individual skin conditions, the surface temperature of the skin and casual lipid level were also determined in each subject. The following are the results obtained from these experiments: 1) the occlusivity of the oil films varied with time, type of oils, their coating amount, physical forms, emulsion type and droplet diameter of the emulsion and 2) the occlusive effect of oils also depended upon the characteristics of the skin such as casual lipid level and TEWL. These results could be explained by the differences in uniformity, spreadability and porosity of the oil films on the skin surface in the residual state. It is believed that the emolliency of the oil can be influenced by these differences. INTRODUCTION It has been always the aim of cosmetic chemists to maintain the skin's softness and freshness and it is considered important to retain moisture in the stratum corneum (1). Emollients, serving not only as lubricants but also forming occlusive films on the skin which retard the water loss from the stratum corneum, render the skin supple and flexible. In this respect, therefore, the emollients have been often termed "occlusive moisturizers" (2). A large number of works have been reported on the theory and measurement of the resistance to water vapor loss of the layer of emollients (3-7). Although their experimental conditions and interpretation of the results differ, it is generally observed that hydrocarbons such as petrolatum strongly inhibit water loss whereas synthetic esters with branched chain tend to transmit water through because of their porosity (8). Unfortunately, there have not been many previous published reports on the effect of the differences in the states of occlusive films on emolliency. Since the occlusivity of the oil is believed to depend greatly on its state on the skin surface, the present study was undertaken to investigate the relation between the residual state of the oil on the skin surface and its occlusive effect. In order to vary the adhering state of oil films, oils 345