12 JOURNAL OF COSMETIC SCIENCE fully informed of the nature of the study and the procedure involved) in a test room of RH 65% + 5% and 20 ø + 0.5øC, for observation of the time needed for film formation. Storage stability of moisture mask containg water-soluble mucilage. The storage stability of the moisture mask was evaluated every two weeks from the change of the apparent viscosity of the moisture mask stored at 4øC. The viscosity measurement conditions were the same as those described above. Color and color difj•rence measurement. An 8.0-g aliquot of vitamin E-containing cream was placed in the cell of a Color and Color Difference Meter (Model JP7100F, Juki Optek Co., Japan) to measure lightness (L value), redness (+a value), greenness (-a value), blueness (-b value), and yellowness (+b value). A blank was used to calculate the color difference. The standard plates of a, b, and L were -0.01, -0.38, and 98.29, respectively. The whiteness was calculated by the equation: a 2 b2] 1/=. W = 100 - [(100 - L) 2 + + RESULTS PROXIMATE COMPOSITIONS OF THE WATER-SOLUBLE MUCILAGE OF &IONOSTROMA NITIDIUM The proximate compositions of the water-soluble mucilage of Monostroma nitidium were 8.5% moisture, 58.44% carbohydrate, 2.51% protein, and 22.62% ash. VISCOSITY OF MOISTURE MASKS Results in Figure 1 show the relationship between shear stress and shear rate of moisture masks containing different types and concentrations of thickening agents at 25 ø _+ 300 250 200 150 50 0 20 40 60 80 100 120 Shear rate (I/s) Figure 1. The relationship between shear stress and shear rate of moisture mask containing different types and concentrations of thickening agents at 25 ø + 0.2øC. HEC: hydroxyethyl cellulose. MC: methyl cellulose. Extract: Monostroma nitidium aqueous extract. ', 2% HEC + 5% humectant. I, 2% MC + 5% humectant. A, 1% HEC + 1% extract. x, 1% MC + 1% extract. O, 2% extract.

WATER-SOLUBLE MUCILAGE IN A MOISTURE MASK 13 0.2øC. Shear stress increased with increasing shear rate. The increase rate of the shear stress decreased with increasing shear rate. At the same shear rate, shear stress was in the order of 2% hydroxyethyl cellulose (HEC) + 5% humectant 2% methyl cellulose (MC) + 5% humectant 1% HEC + 1% Monostroma nitidium mucilages (extract) 1% MC + 1% extract 2% extract. The shear stress of the moisture mask containing 2% extract was significantly lower than that of those containing 2% HEC + 5% humectant or 2% MC + 5% humectant. The results indicated that 2% extract could not be used to replace the thickening agent and humectant in the formula completely. Therefore, different concentrations of extracts and 1% thickening agent were tried in the later studies. Results in Figure 2 show the relationship between the shear stress and shear rate of moisture masks containing 1% HEC and different concentrations of extract at 25 ø + 0.2øC. At the same shear rate the shear stress of the moisture masks were in the order of increasing concentration of the extract. The increase rate of shear stress also decreased with increasing shear rate. Transforming the shear stress and shear rate data in Figures 1 and 2 to a power law equation, the flow consistency index (k), and flow behavior index (n) can be obtained and are listed in Table II. Results show that the flow behavior indexes are all less than 1. This indicates that the moisture masks are pseudoplastic fluids. The higher the concentration of the thickening agents that the moisture mask contained, the more the flow behavior index deviated from 1. In moisture masks con- taining higher concentrations of thickening agent, shear thinning became more pro- nounced. The flow consistency indexes of moisture masks were 87.61 and 39.86 for moisture masks containing 2% HEC + 5% humectant and 2% MC + 5% hurnectant, 180 160 140 ,•, 120 • 80 m 60 40 2O ß ß ß ß ß ß ß ß ß ß ß ß x ß x x x ß x x x x I I I I 0 20 40 60 80 100 120 Shear rate (l/s) Figure 2. The relationship between shear stress and shear rate of moisture mask containing 1% hydroxy- ethyl cellulose and different concentrations of 34onostroma nitidiam aqueous extract ar 25 ø _+ 0.2øC. HEC: hydroxyethyl cellulose. •, 2.0% extract + 1.0% HEC. I, 1.0% extract + 1.0% HEC. &, 0.5% extract + 1.0% HEC. O, 0.25% extract + 1.0% HEC. x, 1.0% HEC.