EFFECT OF MOISTURIZERS (COMBINED OR SINGLE) ON THE SKIN 177 Eight zones (3 × 3 cm each) were delineated on legs and forearms of each volunteer and were randomized to receive eight different applications (test products or remained non- treated Table I, Figure 1). The three test products and their ingredients are presented in Tables II and III. During the study, 18 mg of cream (2 mg/cm2) or 9 μl of toner (1 μl/cm2) was applied only once in the designated zone, and the spray water was applied in a same dosage as toner. All the moisturizers were spread evenly by the same technician. Skin hydration was measured by the trained technician using a Corneometer® CM825 (Courage & Khazaka GmbH, Cologne, Germany) before treatment (t0) and at 2, 4, 6, and 8 h after product applications. A ll volunteers stayed in a controlled room (temperature 22°C ± 2°C, humidity 50% ± 5%) from 30 minutes before the fi rst measurement (baseline) to the last measurement (8 h). Skin hydration difference rate (%) was calculated as follows: ( ) - = × Skin hydration change rate ( % 100 t H H)0 H0 Statistical analysis was performed using the SPSS statistical software, version 19.0 (SPSS Inc, Chicago, IL) and p 0.05 was considered statistically signifi cant. The skin hydration change rate between test products and the nontreated group was analyzed using repeated measures analysis. The skin hydration change among various test products was analyzed using repeated measures analysis or Student–Newman–Keuls test or Dunnett’s T3 test. RESULTS A total of 20 female volunteers with a mean age of 26.6 ± 2.24 years completed the study. The average hydration value at baseline was 35.92 a.u. The baseline values of each ap- plication group had no signifi cant di fferences ( p 0.05 Figure 2). The skin types of test legs and arms were divided into dry and normal skin according to their moisture status (average hydration value at baseline for dry skin is 35 a.u. and for normal skin is 3 5 a.u. Table IV) (10,11). Table I Eight Applications on Each Zone of Forearm or Leg Application t0 2 h 4 h 6 h 8 h C Cream (2 mg/cm2) — — — — T Toner (1 μl/cm2) — — — — T+C Toner (1 μl/cm2) + cream (2 mg/cm2) — — — — C+T Cream (2 mg/cm2) + toner (1 μl/cm2) — — — — C-T Cream (2 mg/cm2) Toner (1 μl/cm2) Toner (1 μl/cm2) Toner (1 μl/cm2) — C-S Cream (2 mg/cm2) Spray water (1 μl/cm2) Spray water (1 μl/cm2) Spray water (1 μl/cm2) T-T Toner (1 μl/cm2) Toner (1 μl/cm2) Toner (1 μl/cm2) Toner (1 μl/cm2) — Untreated — — — — —

JOURNAL OF COSMETIC SCIENCE 178 For normal skin, the effect of each application on hydration change from baseline is il- lustrated in Table V and Figure 3. All treated zones represented a signifi cantly higher hydration change compared to the untreated zone (p 0.05). Cream (including C, C+T, T+C, C-T, and C-S zones) induced a high degree of hydration change for 2 h after applica- tion. Three zones (C, C+T, T+C zones) treated with cream at the beginning but without any continuous moisturizing had a signifi cantly high hydration change 2 h later, which reduced gradually, but still remained elevated for 8 h. These three zones exhibited an alo- gous hydration change at each test point ( p 0.05). C+T and T+C zones might have in- stant higher hydration change than C zone for the fi rst 2 h however, the differences could not be detected even 8 h after application. The order of cream or toner application had little or no effect on the skin hydration. Th e hydration change of C-T zone reduced slowly and even maintained a high level for 8 h due to repeated toner treatment. However, three times repeated applications of spray water led to a rapid decline of hydration change of stratum corneum. Although compared with the cream-treated zone, toner only provided a mild moisturiz- ing effect, and repeated applications of toner induced sustained increase in hydration change rate that exceeded cream-treated zone 8 h later. In addition, cream applied with Figure 1. Eight applications (test products or remained untreated). Table II Information on the Three Cosmetics Used in This Study Moisturizer Product name Manufacturers Cream, C Natural skin care moisturizing and softening cream Winona®, Kunming, China Toner, T Natural skin care anti-sensitive moisturizing toner Winona®, Kunming, China Spray water, S Thermal water Avene®, Pierre Fabre, France