8 JOURNAL OF COSMETIC SCIENCE 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0.5 1 1.5 2 2.5 Concentration (%) Figure 2. Effect of adding different molecular weights and concentrations of water-soluble chitosans on the absorbance (490 nm) of moisture masks (MW: ', 2.42 x 10 6 Da I, 1.62 x 10 6 Da &, 1.17 x 10 6 Da). chitosans or methyl cellulose (86,000 Da), the electrical capacitance increase ratio in- creased to 60%-65%, then decreased, and finally leveled off. Electrical capacitance increase ratios after 60 min were 38%, 34%, and 31% for moisture masks containing 2% U3 chitosan, 2% U30 chitosan, and 2% U120 chitosan, resprectively. The electrical capacitance of the moisture mask containing water-soluble chitosans was significantly higher than that of the mask containing 2% methyl cellulose, which had an electrical capacitance increase ratio of 26% after 60 min. Table V Effect of Adding Different Molecular Weights and Concentrations of Water-Soluble Chitosans on the pH and Safety of Moisture Masks Concentration (%) Draize score pH Control 0* 6.5-6.7 U3 chitosan O.5 0 6.3-6.5 1.0 0 6.3-6.5 2.0 0 6.3-6.5 U30 chitosan 0.5 0 6.2-6.5 1.0 0 6.2-6.5 2.0 0 6.2-6.5 U120 chitosan O.5 0 6.3-6.5 1.0 0 6.3-6.5 2.0 0 6.3-6.5 * Draize score of 0 indicates no erythema. U3 chitosan, U30 chitosan, and U120 chitosan: the same as in Table I.

MOISTURE MASKS AND CHITOSANS 9 7O o 60 • 50 • 40 o 30 " 20 • 10 0 20 40 60 80 Time (min) Figure 3. Changes of the capacitance increase ratio with time after applying moisture masks containing 2% different molecular weight water-soluble chitosans measured at 20 ø _+ 0.5øC and 75% RH. (MW: ', 2.42 x 106 Da I, 1.62 x 106 Da ', 1.17 x 106 Da O, 2% methyl cellulose, 8.6 x 104 Da). FILM-FORMATION TIME The results in Table VI show film-formation time decreasing from 14.2 to 10.8 min with increasing concentration from 0.5% to 2.0% of U3 chitosan in the moisture mask. This pattern was also true for moisture masks containing lower molecular weight water- soluble chitosans of the same concentration. DISCUSSION VICOSITY OF MOISTURE MASKS The apparent viscosity of moisture masks decreased with increasing shear rate (Figure 1). The results indicate that moisture masks containing water-soluble chitosans were shear- Table VI Effect of Adding Different Molecular Weights and Concentrations of Water-Soluble Chitosans on the Film-Formation Time (min) of Moisture Masks Film formation time Concentration (%) Control U3 chitosan U30 chitosan U120 chitosan 0.5 13.8 b'c 14.2 b 15.4 • 15.6 • 1.0 12.4 a 13.4 c 14.4 b 2.0 10.8 f 11.6 e 11.8 • * a-f values (n = 3) followed by the same superscript are not significantly different (p 0.05 by Duncan's multiple-range test). U3 chitosan, U30 chitosan, and U120 chitosan: the same as in Table I.