CONSISTENCY DEVELOPMENT OF A MODEL CREAM 345 glomerates suggest that the waxes and oils of the internal phase separate as distinct entities. Thermal optical videomicroscopy and trace substance analysis have identified the phase-separated components of the agglomerates as cetyl alcohol, stearyl alcohol, and cetyl palmitate. The absence of isopropyl myristate in the trace substance analysis has verified the conclusion that the oil and wax components phase separate as distinct entities. ACKNOWLEDGMENTS The authors wish to express their appreciation to D. S. Aldrich and T. M. Ryan for performing the trace substance analysis. REFERENCES (1) G. M. Eccleston, The microstructure of semisolid creams, Pharmacy International, 63-70 (March 1986). (2) B. •d. Barry and G. M. Ecclesron, Influence of gel networks in controlling consistency of O/•d emulsions stabilized by mixed emulsifiers, d. Texture Studies, 4, 53-81 (1973). (3) G. M. Eccleston, The influence of fatty alcohols on the structure and stability of creams prepared with polyethylene glycol 1000 monostearate/fatty alcohols, Int. J. Cosmet. Sci., 4, 133-142 (1982). (4) G. M. Eccleston, Structure and rheology of cetomacrogol creams: The influence of alcohol chain length and homologue composition, J. Pharm. Pharmac., 29, 157-162 (1977). (5) G. M. Eccleston, "Properties of Fatty Alcohol Mixed Emulsifiers and Emulsifying Waxes," in Ma- terials Used in Pharmaceutical Formulation.' Critical Reports on Applied Chemistry, A. T. Florence, Ed. (Blackwell Scientific Publications, London, 1984), Vol. 6, pp. 124-156. (6) B. W. Barry and G. M. Saunders, Kinetics of structure build-up in self-bodied emulsions stabilized by mixed emulsifiers, J. Coll. Interface Sci., 41, 331-342 (1972). (7) L. E. Pena, B. L. Lee, and J. F. Stearns, Secondary structural rheology of a model cream, Midwest Regional Meeting of the American Academy of Pharmaceutical Scientists, Chicago, May 15, 1989 (submitted for publication). (8) H. E. Junginger, Colloidal structures of O/W creams, Pharm. Weekbl. Sci. Ed., 6, 141-149 (1984). (9) H. K. Patel, R. C. Rowe, J. McMahon, and R. F. Stewart, A systematic microscopical examination of gels and emulsions containing cetrimide and cetostearyl alcohol, Int. J. Pharm., 25, 13-25 (1985). (10) The Merck Index, 10th ed, M. Windholz, Ed. (Merck and Co., Inc., Rahway, NJ, 1983), pp. 282, 1259. (11) T. M. Ryan and D. S. Aldrich, Internal memo--The Upjohn Company (December 8, 1989).

j. Soc. Cosmet. Chem., 44, 347-371 (November/December 1993 Quantification and prevention of hair damage M. L. TATE, Y. K. KAMATH, S. B. RUETSCH, and H.-D. WEIGMANN, TRI/Princeton, PO Box 625, Princeton, NJ 08542. Received June 22, 1993. Presented at the Annual Scientific Seminar of the Society of Cosmetic Chemists, Baltimore, May 6-7, 1993. Synopsis Methods were established to evaluate primary chemical damage to hair from oxidative and reductive treatments. The effects of subsequent grooming treatments (combing, shampooing, and conditioning) were documented. Analytical methods used to evaluate hair damage included surface analysis through micro- fluorometry, scanning electron microscopy, and Wilhelmy balance wettability. Structural damage was evaluated by studies of dye diffusion, amino acid composition, mechanical properties, and fatigue behavior. INTRODUCTION Through efforts to improve appearance, hair may be exposed to damaging chemical and mechanical modifications. Once irreversible damage has occurred, other hair cosmetics are used to prevent further deterioration during subsequent grooming. For optimal product development, a quantitative assessment of hair damage is required so that the protective effects of hair care formulations can be established. Over the last 25 years, much research has been done on hair damage from chemical treatments (bleaching and permanent waving) and grooming, including shampooing and combing. Beyak (1) established that both bleaching and perming can result in losses of up to 20% in mechanical properties. Robbins and Kelly (2,3) studied the amino acid composition of chemically altered hair and found changes from both bleaching and permanent waving. Changes in hair properties from grooming have also been widely studied. The work has centered on microscopy and on wearing away the cuticular layer, which is five to ten scales thick (4). Cosmetic treatments, such as bleaching and perming, can be severe enough to damage or completely wear away the cuticle, as shown by Robinson (5). Normal grooming of hair, including combing, brushing, and shampooing, also pro- duces damage that is progressive. This phenomenon was described in detail by Garcia et al. (6). Most of the research has centered on damage from either chemical cosmetic treatments or from grooming practices. Chemical damage has been studied primarily by analyses of 347