CATIONIC CONDITIONING COMPOUNDS 83 conceivably may include penetration of especially the lower-molecular-weight ones, into the intermacrofibrillar regions of the cortical cells. The three conditioners investigated appear to behave quite differently. Both high- molecular-weight cationics deposit at the scale edges and on the scale faces after only one application, and additional deposition after multiple applications does not appear to be significant. The low-molecular-weight CETAB, on the other hand, shows no significant deposits after a single application and after multiple applications. Fibers display "clean" surface cuticles, except for occasional light deposits. The decrease in the scale-lifting phenomenon during extension suggests improved cu- ticular cohesion. Whenever the high levels of scale lifting cannot occur in response to the stresses of extension, alternate paths are found to dissipate the stress. Most often, severe scale cracking is observed as the alternate mechanism of stress release. However, this scale cracking generally occurs at very high levels of extension. Hair fiber failure at rather high extension levels and the infrequency of the high levels of scale lifting (extreme and common scale lifting) indicate cationic-induced reinforce- ment of the cuticula, specifically in the weakly cross-linked, nonkeratinous regions. For example, cationic-induced, increased cohesion of the CMC may well glue the surface cuticles down and thus prevent high levels of scale lifting during extension, eventually resulting in stress release through cracking at higher extension. Increased cohesion in the endocuticle of the surface cuticle cell, on the other hand, may prevent endocuticular failure during fiber extension and result in lifting of the intact surface cuticle cell, whenever it can occur. CREEP Repeated applications of the polymeric cellulose derivative significantly change the creep behavior of hair fibers in comparison to controls. Low levels of overall creep, under constant stress, and the fact that only fine diameter fibers show an initial creep, suggest that multiple treatments with cationic quaternary compounds reinforce the cuticula. It appears that in fine fibers at low strain rates, such reinforcement of the cuticula has a direct bearing on the deformation behavior of the cortex. Cationic-induced creep resis- tance further supports the cuticle-reinforcing effect of the cationics studied in this work. ACKNOWLEDGMENTS This study was carried within the framework of the TRI Core Technology Project "Analysis and Quantification of Hair Damage," sponsored by companies in the inter- national cosmetics industry. The authors would like to thank the sponsors for their financial support. REFERENCES (1) S. B. Ruetsch and H.-D. Weigmann, Mechanism of tensile stress release in the keratin fiber cuticle. I.J. Soc Cosmet. Chem., 47, 13-26 (1996). (2) C. R. Robbins, Chemical a,d Physical Behavior of Huma, Hair (Springer-Verlag, New York, 1988), p. 199. (3) C. R. Robbins, ibid., p. 202. (4) R. E. Walpole and R. H. Myers, Probability a,d Statistics for Engi,eers a,d Scie,tists (Macmillan, New York, 1972), p. 261. (5) J. A. Swift, I,t. J. Cosmet. Sci., 13, 143 (1991).

j. Cosmet. Sci., 54, 85-111 (January/February 2003) Papers Presented at the 2002 Annual Scientific Meeting and Technology Showcase (Thursday's Program) December 5-6, 2002 New York Hilton New York, NY 85