LIQUID CRYSTAL MAKE-UP REMOVER 23 and the other was wiping off the remover with tissue after applying either O/W cleansing cream or liquid crystal gel (0.075 mg/5.0 cm 2) on the upper arms and massaging for 25 seconds. Observations and image analysis of corneocytes isolated from stratum corneum by the tape stripping method were made twice, before and after the three-week treatment, by using a scanning image analyzer (JEOL Co. Model SIA-3) attached to a color video microscope system (x 1000) (Wilson Co. Model CVM7000). The sizes of corneocytes were analyzed by using an image analysis computer program (PIAS Co. LA-500). The corneocytes from nine panelists were examined and average sizes of 40 to 50 cells were calculated for each test. Amount of remaining remover. The mixture of a nonionic surfactant (EOD-20), TGO, Parsol MCX, and 70 wt% aqueous solution of glycerol in the ratio of 25:48:2:25 by weight, as a model formula of make-up remover, was applied to the forearm (350 mg/32 cm2). After rubbing for 25 seconds, the mixture was rinsed off with water. The re- maining remover was extracted by wiping three times with cotton soaked with a mixture of acetone and ether (1:1). Quantitative analysis of Parsol MCX as the marker was followed by using an ultraviolet visible spectrophotometer (}t = 309.2 nm) (Beckman Co. Model DU-7) after it was extracted from the cotton with 20 ml of CHCL 3 and CH3OH (3:1). Cleansing ability. A mixture of 5 wt% of ceresin, 5 wt% of microcrystalline wax, 10 wt% of carnauba wax, 70 wt% of diisostearyl malate, 8 wt% of D. & C. Red No. 7, and 2 wt% of titanium dioxide was used as a model of oily cosmetics. It was applied to the forearms (20 mg/16 cm2). 400 mg of remover was applied, followed by rubbing for 25 seconds and rinsing with water. The cosmetic residue was observed with a DSA, and its amount was converted into numerical values with an image analyzer in order to compare the cleansing ability. In this study, the amount of residues accumulated in the pores and sulcus cutis of the skin was neglected, and only the surface residue was taken into account. Phase diagrams. The samples used for phase equilibria were weighed directly into glass test tubes with teflon-sealed screw caps and were kept in a thermosrated bath at various temperatures. Samples with high viscosity were agitated at a high temperature in order to accelerate the achievement of equilibrium. The different phases were identified by visual observation with and without crossed polarizers. The liquid crystalline phase structure was identified by its optical texture (3,4) by means of microscopic observation with polarized light, and by X-ray diffraction (5,6). A Nikkon XF-2 microscope equipped with thermoregulator (Mettier Co., Thermosystem FP-800), a small-angle X-ray diffractometer (Rigaku Co., Geigerflex RAD-rB equipped with small-angle X-ray diffraction camera), and a wide-angle diffractometer (Shimadzu Co., XD-7A) were used to examine and confirm the structure and the state of the liquid crystalline phase. Cu-Kot radiation (}t = 1.54 A) was used in both X-ray diffractom- etries. Rheological properties. The rheological properties of emulsions were measured with a coaxial-cylinder viscometer (Rotovisco RV-2 of Haake Co., LTD.). Droplet size distribution of emulsion. The droplet size distributions of emulsions were determined with a Coulter Counter (Model TA-II) and a Coulter Submicron Analyzer (Model N4).

24 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS RESULTS AND DISCUSSION STATE OF REMAINING MAKE-UP COSMETICS AND PROBLEMS WITH CONVENTIONAL MAKE-UP REMOVER Oil-based cosmetic residues, such as waterproof foundations and eyeshadows, often remain on the skin even after cleansing with a make-up remover. By using a direct skin analyzer, the skin surface was observed with 200X magnification value, and the oily impurities were found to remain within the pores and sulcus cutis of the skin even though the crista cutis of the skin seemed to be clean (Figure 1). A similar tendency was observed with any kind of cleansing product. In general, make-up removers are of a solvent type. The principle of cleansing with a solvent-type remover is dissolving and dispersing oily impurities into the oil base. They are directly applied to the skin, followed by dissolving the impurities by rubbing, and then removed. The schematic illustrations in Figure 2 show the cleansing process of two kinds of cleansing creams, water-in-oil (W/O) and oil-in-water (O/W) types, which are both typical solvent-type make-up removers. Their fundamental cleansing mechanisms are the same in terms of dissolving and dispersing oily impurities within the oily phase of the emulsion, but the consecutive removal process is different. A W/O cleansing cream can easily dissolve oily impurities due to its oil-based outer continuous phase, though it is incapable of being rinsed off, and is usually wiped off. An O/W cleansing cream, on the other hand, cannot dissolve oily impurities immediately after the appli- cation because of its water-based continuous phase. The rubbing, however, induces evaporation of water and coalescence of oil droplets in the emulsion, which leads to phase inversion from O/W to W/O. Then the oil-based impurities are dissolved in it. Since a W/O emulsion formed by phase inversion still contains hydrophilic emulsifier that can produce an O/W emulsion, the cleansing cream can disperse in water by reinversion during the rinsing process. An O/W cleansing cream, therefore, can be removed by either the wipe-off or rinse-off method, but the efficiency of the latter has not yet been seriously considered. The physical manipulation of wiping off greatly contributes to the cleansing ability of the conventional make-up removers. Its physiological influences on human skin, how- Figure 1. State of remaining make-up cosmetics on the skin after cleansing.