J. Soc. Cosmetic Chemists, 17, 607-621 (1966) Evaluation of Certain Factors Influencing Oil Deposition on Skin After Immersion in an Oil Bath M. E. STOLAR, Ph.D.* Presented May 10, lb66, New York City Synopsis--Previously developed methods for determining quantitatively the amount of oil and recording the oil film deposited on the skin after immersion in oil baths were utilized to evaluate various oils of potential use in bath oil formulations. The effect of the presence of various surfactants in mineral oil on the amount and skin coverage of the deposited oil film was determined. The existence of a relationship between spreading coefficient values and the amount or skin coverage of the deposited oil film was investigated. The use of bath oils in the treatment of dry scaly skin has gained favor in the last few years. Originally, dry skin was explained on the assumption that the surface lubricating lipid film was qualitatively or quantitatively modified or even missing (1). Blank (2) and Borota (3) demonstrated that cornified material obtained from callus remained soft and pliable as long as it retained moisture. To extend the duration of moisture retention, as indicated by softness and pliability, the tissues were coated with oil and placed on a wet surface. Normal baths are frequently contraindicated due to their degreasing and drying effects on the skin (4). Pillsbury et al. (5) claimed that im- mersion of the skin in water followed by topical application of grease demonstrated beneficial effects. These may be attributed to hydration of the stratum corneum due to a decrease in the rate of moisture loss * Dome Laboratories, Div. Miles Chemicals, Inc, 125 West End Ave, New York• N. Y, 10023. 607

608 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I Effect of Grade of Mineral Oil (0.02%) Dispersed in Water (40øC) on Oil Deposition on Skin aft(r 15 Minutes of hnmersion Amount Amount Con-Fosition in of Oil •" Specific Saybolt Added Grade of Naph- Paraf- Gravity Viscosity to Bath Oil thehie fiuic at g0øF at 100øF (g) Mineral oil USP'* 40 () 6(/. 0 0.88,5 850 0. 200 Mineral oil NF •' 37.0 ( •1.0 0. 852 88 0. 200 Mineral oil technical" 30.0 70. f) 0. 882 55 0. 200 of Oil •/• of Eluted Oil De- from posited Skin (g) on Skin 0. 044 •' 22.2 O. 06? 81.0 0. 080 • 40.0 Supplied by Sonnenborn Chemical and Refining Company, New York, N.Y. Average of six determinations. Table II Spreading Coefficient Values for Various Grades of Mineral Oil Surface Specific Tension Interfacial Spreading Grade of Gravity at 25 øC Tension Coefficient Oil • at 60øF (dynes/era) at 25øC at 25øC Mineral oil USP 0. 885 •2.2 44.6 -- 4.8 Mineral oil NF 0. 852 33.4 41.9 -- 8.8 Mineral oil technical 0. 832 81.4 41.8 0 Supplied by Sonnenborn Chemical and Refining Company, New York, N.Y. from the skin without affecting the rate of moisture diffusion from the underlying tissues (1). Clinical studies attesting to the beneficial effects of bath oils have been reported in medical literature (6-9). Commercially available bath oils may be classified as either spreading or dispersible types. The spreading type tends to form a surface film of oil on the water, while the dispersible type forms a dispersion of fine droplets of oil throughout the water. Both types are claimed to deposit an oil film on the immersed skin. Knox (10) described the development of a water dispersible oil bath which is deposited on skin surfaces. Taylor (11) reported that about twice as much oil is deposited from aqueous dispersions of mineral oil as from vegetable oil. Similar conclusions were reached by Knox (12). Taylor's results are based on the difference between the initial amount of oil present in an immersion cylinder and the residual amount after immersion for a specified period of time. This difference is indicative of the amount of oil deposited on the treated skin surface. Stolar (13) recently developed a method for determining the actual amount of oil deposited on the skin after immersion in an oil bath and