J. Soc. Cosmetic Chemis:s, 20, 777 793 (Dec. 9, 1969) Studies on Lanolin Shampoo Systems Derivatives in SHIRLEY ANN D•RAGON, B.S., PATRICIA M. DALEY, B.A., HENRY F. MASO, B.S., and LESTER I. CONRAD, B.S.* Presented May 1G, 19•8, Fifth IFSUC Congress, Tokyo, Japan Synopsis--The influence of six different water-soluble ethoxylated lanolin derivatives and of an ethoxylated stearyl alcohol on the foam characteristics of a typical shampoo system was determined using relatively simple laboratory procedures. Reproducible quantitative meas- urements of specific foam volume and per cent drainage after five minutes were utilized to characterize the foams. Acceptable limits were established for these criteria. The additives were tested at 1, 2, and 5% in deionized water at 23 ø and 45øC in moderately hard water at 23øC and in the presence of synthetic sebum in deionized water at 45øC. Sig- nificant differences between the foam properties of the control shampoo and of the shampoos containing the additives were observed. A pronounced response to concentration of additive was also detected, establishing the value of these test methods for evaluating shampoo addi- tives and for determining the concentration required to optimize foam characteristics. The data indicate that the addition of the appropriate ethoxylated lanolin derivative at its opti- mum concentration can stabilize shampoo performance under a variety of use conditions. INTRODUCTION Ethoxylated lanolin derivatives are used in shampoos for groom- ing effects, gloss, and solubilization of antiseptics, perfume, and other oil-soluble additives. Although lacking factual proof, many cosmetic formulators anticipate a reduction in foam volume and/or foam stability when these lanolin derivatives are added, but reason that the benefits to be obtained outweigh the expected concomitant "disadvantages." * American Cholesterol Products, Inc., Amerchol Park, Edison, N.J. 08817. 777

778 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In this investigation, data were obtained on the effect of six different water-soluble ethoxylated lanolin derivatives on the foam characteristics of a typical simple shampoo system. CjENERAL CONSIDERATIONS The generation of foams and the evaluation of foam properties are the subjects of continuous study by physical chemists and cosmetic chemists. While the physical chemist is concerned primarily with the fundamental aspects of bubble formation, size, and stability, the cos- metic chemist must not only understand these principles but must reconcile them with the practicality of intended usage. Thus the "ideal" foam that each seeks is not necessarily the same. Monodisperse foams, characterized by the identical dimensions of all the bubbles, are preferred for physical chemical studies (1). These foams are best obtained by forcing gas through a capillary tube inserted in a solution of the foaming agent. But the properties of these mono- disperse foams are quite different from those of the polydisperse foams formed during shampooing. Chemists working in the cosmetic and toiletries industries have sug- gested several methods for generating foams with characteristics that more closely approximate those of the foam developed under use condi- tions. The Ross-Miles test produces foam by dropping from a pre- determined height a portion of a solution of a foaming agent into an- other portion of an identical solution (2). Although this method ade- quately measures flash-foaming ability and foam decay, the foams gen- erated under these conditions are not similar in structure to those formed on the head. Later investigators examined the foams produced by perforated discs or screens operated in plunger fashion through dilute solutions of foaming agents in glass cylinders. Barnett and Powers developed a mechanized foam-generating apparatus of the plunger type which per- mitted the simultaneous evaluation of a series of solutions (3). They acknowledged that these laboratory tests had not been correlated with salon tests, the only accurate evaluation of shampoo foams. New studied the properties of foams generated by the Sunbeam Mix- master at various speeds and times of beating. He characterized the foams by determining specific foam volume, viscosity, light transmis- sion, bubble size distribution, specific surface, and foam drainage. Us- ing these same measurements, New also evaluated foams generated on