564 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS zIcknow/edgments: The authors are grateful to Dr. Milo Gibaldi for his assistance during the conduct of this study. The authors also wish to express their appreciation to the following companies for supplying the materials listed: 1. Freon Propellants from E.I. du Pont de Nemours Co., Inc., Freon Products Division, Wilmington, Del. 2. Aerosol valves from the Risdon Manufacturing Co., Naugatuck, Conn. 3. Aerosol plastic coated bottles from the Wheaton Plasti-Cote Com- pany, Mays Landing, N.J. 4. Igepal surface-active agents fi'om Antara Chemicals Division of General Aniline & Film Corp., New York. (Received January 10, 1964) REFERENCES (1) J. L. Kanig, Aerosol Age, 6, 35 (May, 1961). (2) J. L. Kanig and R. M. Cohn, Proc. Sci. Sect. Toilet Goods Assoc. No. 37, 19 (1962). (3) J. L. Kanig and C. T. Shin, Ibid. No. 38, 55 (1962). (4) J. L. Kanig, •. Pharm. Sci., 52, 513 (1963). (5) Lloyd I. Osipow, Surface Chemislry, Theory and!ndustrial Applications, Reinhold Publish~ ing Corp., 1962, p. 165. (6) P. Becher and N. K. Clifton, •7- Colloid Sci., 14, 519 (1959). (7) H. L. Greenwald, G. L. Brown, and M. N. Fineman, Anal. Chem., 28, 1693 (1956). (8) Freon Aerosol Report No. FA 3, Freon Products Div. E. I. du Pont de Nemours Co., Inc., Wilmington, Del.

•t. 8oc. Cosmetic Chemists, 15, 564-577 (1964) PROBLEMS IN COSMETIC RHEOLOGY By JoHN H. WooD, PH.D., WALDRON H. G•.Es, PH.D., and GREGORY CATACALOS, B.S.* Presenled December 3, 1963, New York City ABSTRACT The role of empirical measurements in cosmetic theology is ex- amined and defined. The artifacts appearing in presumably ab- solute theological data are explained on the basis of the non-New- tonian behavior of the system. The limitations of single point mesure- ments are reviewed. Emphasis is placed upon the role that slippage and plug flow have in cosmetic measurements, and it is suggested that ribbed bobs and cups and star bobs have not been sufficiently utilized until now. Viscoelasticity is a prevalent phenomenon in cosmetic theology but has not been characterised in cosmetic measure- ments. INTRODUCTION "Give me a number, not a story" is a philosophy that may be said to have dominated most of cosmetic rheology. The fundamental rheolog- ical examination of a cosmetic can be best represented only by a full rheogram. Unfortunately, this rheogram can only be presented either graphically or tabularly by a series of numbers. Alternately, various empirical devices for the measure of slip, consistency, viscosity, ease of delivery, etc., abound. These, in general, give single numbers, on a relative scale, for the property or combination of properties involved by the test. There have been many papers dealing with some aspect of cosmetic theology published in this Journal and elsewhere. However, most have dealt with the fundamentals of rheology or have merely used cosmetics for routine rheologic measurements. What, then, can be so different or so special about cosmetics? In essence, it is the formulator's need for values which bear some relation to the consumer's subjective evaluation, often so critical to the acceptance of a product. * Bristol-Myers Products Division, Hillside 5, N. J. 565