625 LINIMENT OF NAFTALAN OIL Developed cosmetic compositions were tested for stability in accordance with the Colipa 2004 guidelines (17). Their pH of the bath foam, gel, and cream was determined by the method described in ASTM D1172-95 (reapproved in 2001) using a SevenEasy S20 pH meter equipped with an InLab 410 glass electrode (both from Mettler Toledo, Columbus, Ohio) (18). Bath foam. Foaming ability and stability were evaluated in accordance with the standardized Ross-Miles method, which consisted in measuring the height of a column of foam formed when a water solution of the composition with a concentration of 1 wt% under study was dropped onto a surface of the same solution from a fixed height (19). Foam stability was defined as the ratio of the height of the column after 5 min and at the initial moment of time. Determination of the viscosity of the compositions was carried out at a temperature of 22 ± 2°C on a sinusoidal vibration viscometer SV-10 (A&D Instruments, Japan). Gels. The rheological properties and strengths of the gels were investigated dynamically using a Reotron rotational viscometer, consisting of two coaxial cylinders. The range of revolutions of the inner cylinder was from 0 to 550 s–1. The spreadability of gel systems was evaluated by the method proposed by Bachhav and Patravale (20). It consisted of measuring the diameter of the spreading of the gel after placing it between two glass plates and loading them with a weight of 100 g at a temperature of 37 ± 2°C. Creams. The microstructure of the creams in the concentration range 0.2 to 0.9 wt% was studied by optical microscopy using Olympus BX 51 (Olympus Optical Co., Ltd., Japan). The sample was placed on a microscope slide, pressed on top with a coverslip. A magnification of ×1,000 was used. The droplet size was measured using software Microimage version 4.0 (Olympus). The type of emulsion was determined by the dilution method. The determination of emulsion stability was measured in the centrifugal machine (Nahita Centrifuges Model 2652, Auxilab S.L., Spain) at 1,008 relative centrifugal force. Test tubes were filled with 15 to 20 mL of the emulsion and then centrifuged for 30 min, with the state of emulsion checked every 10 min. If the emulsion remained homogeneous after 30 min, it was considered to have proper stability. Table III Formulation of the Cream With LNO Component Concentration, % A. Oil phase Isopropyl myristate 4.0 Almond oil 6.0 Mineral oil 10.0 Steareth-20 5.0 Cetearyl alcohol 2.0 Cyclomethicone 1.0 Stearic acid 4.0 Glyceryl stearate 2.0 LNO 0.2–0.9 Perfume composition 0.2 B. Water phase Glycerin 5.0 Conservation agent 0.1 Deionized water Up to 100.0

626 JOURNAL OF COSMETIC SCIENCE To assess the effectiveness of the developed creams, skin topography was evaluated: the stratum corneum hydration (SCH) and fat content were measured. The study involved 10 healthy volunteers (average age 26 ± 3 y) without episodes of dermatologic diseases with normal skin type. These studies do not contradict the ethical principles of the Helsinki Declaration all volunteers gave their informed written consent. The sample was applied after 30 min of the acclimatization period on the back side of the nondominant hand on the medial side, and a cream without liniment was placed on the lateral side as a control (21). Short-term measurements were carried out in vivo 60 and 120 min after application of the composition to the skin surface using an EH-900U multifunction analyzer (Sunwin Technology Co., Ltd., China) under conditions of controlled temperature (22 ± 2°C) and humidity (35 ± 5%). STATISTICAL ANALYSIS The measurement results of the pH of cosmetic compositions, foaming ability and viscosity of bath foam, size of drops of the cream, and skin parameters after its application were processed using STATISTICA 6.0 software (Version 6-Index, Stat-Soft Inc., Tulsa, Oklahoma). The confidence level p 0.5 was considered statistically significant. DISCUSSION AND CONCLUSIONS When developing compositions with LNO oil, we were guided by the recommendations and standard formulations used in cosmetics technologies (22,23). It was possible to obtain sedimentation, aggregative and thermally stable (creams), optically transparent (gels, bath foam) compositions in the concentration ranges of LNO from 0.2 to 0.9 wt%. The pH values of the systems in this range of liniment concentrations are 5.3–5.9 ± 0.01–0.02, which is close to the physiologic value of the skin’s hydrogen index (approximately 5.5) and corresponds to the optimal range for each type of product (18). All cosmetics are characterized by high thermal and colloidal stability. BATH FOAM Foam formation and its stability are important criteria for consumers when choosing a detergent. The nature of the change in the main parameter of foaming H 0 depending on the concentration of LNO was determined by the Ross-Miles method (Figure 1). Figure 1 shows that the LNO makes a significant contribution to the process of foaming—an increase in the maximum volume of foam is observed compared with the base composition. Obviously, this is because of the presence of surface-active components in the LNO. A correlation was found between the results and viscometric data (Figure 1). Apparently, the observed effects are associated with the encapsulation of oil droplets in the foam (24), which causes the rate of fluid outflow from the Plateau-Gibbs channels to slow and the mechanical strength of the foam film to increase. The highest height of the foam column and the optimal viscosity are observed with a liniment content 0.9 wt%. Foam stability of all compositions had high, close to 1, values.