DYNAMIC HAIRSPRAY ANALYSIS 83 of the texture analyzer at 90% RH. This test was usually performed after the stiffness analysis was completed, by increasing the relative humidity in the environmental cham- ber from 50% to 90% and following the variation in peak force as a function of time. The results obtained for four polymers, poly(vinylpyrrolidone), butyl ester of PVM/MA copolymer, acrylates copolymer, and vinyl caprolactam/PVP/dimethylamino- ethyl methacrylate copolymer, are shown in Figure 7. The results indicate a gradual decrease in stiffness to a level characteristic for untreated hair for a hygroscopic polymer such as PVP, intermediate humidity resistance for butyl ester of PVM/MA copolymer and acrylates copolymer, and only a small drop in stiffness for humidity-resistant material such as vinyl caprolactam/PVP/dimethylaminoethyl methacrylate copolymer. The instrument was also capable of detecting an increase in tackiness of hair treated with PVP after extended exposure to high humidity. CONCLUSIONS A new, objective hairspray testing method, termed dynamic hairspray analysis, was developed to simultaneously measure several properties of hairsprays such as the rate of drying, duration of tack, maximum tack forces, and the stiffness of hair before and after hairspray application. The technique employs a commercial instrument, the texture analyzer, and hair tresses in the form of omega loops. All investigated parameters could be determined with a reproducibility of about 20-30% in experiments involving manual activation of aerosol cans. An alternative method of treatment, which allowed for a deposition of an exact amount of polymer on a hair sample, yielded a higher precision lOO .•© •= Vinyl CaprolacCopolymerMethacrylate so •= [] Dimethylaminoethyl ' •= 6o•- •' eeee IAAA eeeeee ß ß ß ee Bu•lEsterofPVMCopolym • • AA A Ac•lates Copolymer 20 '.,.• Poly(vinylpyrrolidone) o i i I I 2 4 6 8 Thousands Time (sec) Figure 7. Stiffness as a function of time for polymer-treated hair at 90% RH.

84 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS of 10-20%. It allowed for a quantitative investigation of both model and commercial systems in terms of stiffness, tackiness, and resitance to high humidity. ACKNOWLEDGEMENTS The authors acknowledge useful discussions with J. Kosiek and K. Krummel. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (lO) (11) (12) (13) (14) (15) S. H. Ganslaw and F. T. Koehler, Evaluation of hair fixatives--A new technique utilizing torsional measurements, J. $oc. Cosmet. Chem., 29, 65 (1978). F. Frosch and F. Vogel, Parfums, Cosmetiques, Aromes, 89, 71 (1989). W. Hinz, Air spray for hairspray, Manufact. Chem., 64 (7), 30 (1993). J. Guth, J. Russo, T. Kay, N. King, and R. Beaven, Addressing the low VOC hair spray issue, Cosmet. Toileter., 108 (11), 97 (1993). J. Guth, Getting to 55% and beyond, in Spray Technology & Marketing, 26 (September 1994). H. Zahn and G. Blankenburg, Action of alcohol/water mixtures on wool, Text. Res. J., 34, 176 (1964). M. Feughelman, The physical properties ofalpha-keratin fibers,J. Soc. Cosmet. Chem., 33, 385 (1982). A. L. Micchelli and F. T. Koehler, Polymer properties influencing curl retention at high humidity, J. $oc. Cosmet. Chem., 19, 863 (1968). P. Diaz and M. Y. M. Wong, Set relaxation of human hair, J. Soc. Cosmet. Chem., 34, 205 (1983). R. Randall Wickett, J. A. Sramek, and C. M. Trobaugh, Measurement of the adhesive strength of hair-hairspray junctions, J. Soc. Cosmet. Chem., 43, 169 (1992). R. W. Rance, Studies of the factors controlling the action of of hair sprays. I. The spreading of hair spray resin solutions on hair, J. Soc. Cosmet. Chem., 24, 501 (1973). R. W. Rance, Studies of factors contr611ing the action of hairsprays. lI. The adhesion of hairspray resins to hair fibers, J. Soc. Cosmet. Chem., 25, 297 (1974). R. W. Rance, Particle size distribution measurement of hair sprays using an image-splitting particle size analyzer, J. Soc. Cosmet. Chem., 23, 197 (1972). R. W. Rance, Studies of the factors controlling the action of hair sprays. III. The influence of particle velocity and diameter on the capture of particle by arrays of hair fibers, J. Soc. Cosmet. Chem., 25, 545 (1974). E. Walls and E. Hardy performed a preliminary study of adhesive properties of hairspray solution spread on flat, metal substrates, as a function of drying time (ISP internal reports).