DYNAMIC HAIRSPRAY ANALYSIS 81 is evident from the data presented in Figure 4, and this result is consistent with the measurements reported by Hinz (3). The method was also employed to analyze a series of eight commercial compositions labelled as "soft" and "hard" holding formulations. The results are presented in Figure 5, which demonstrates a good differentiation in stiffness values between these two types of hairspray products. ANALYSIS OF TACKINESS The analysis of tackiness during drying of hairspray resins on the surface of hair was carried out by applying 0.07 g of a hairspray solution (polymer concentration 5.71% w/w) to a dry loop of hair and following the time dependence of adhesive forces by intermittent flexing in a texture analyzer. A typical example of this experiment is presented in Figure 6, which illustrates an increase in duration of adhesive forces for compositions, based on ethyl ester of PVM/MA copolymer, containing progressively higher levels of water. The observed average tackiness periods (three measurements) were 194 ñ 6 s, 292 ñ 28 s, and 540 ñ 100 s for 100% VOC, 80% VOC, and 55% VOC compositions, respectively. It is also noteworthy that the magnitude of the tack forces do not increase for water-containing hairspray solutions. On the contrary, the results of our experiments point to a progressive reduction in adhesion between the probe and the film of a drying hairspray solution for compositions of lower VOC content. STIEFNESS REDUCTION AT mGH HUmDrilY The ability of various resins to resist exposure to high humidity was tested by the use 35 { Hard Hold Soft Hold • 20 15 20.9:kl.3 20.14-0.9 20.14-1.4 17.84-4.1 ...................... 15.8 4-4.0 13.7+3.1 11.1+3.1 lO o Product 1 Product 2 Product 3 Product 4 Product 1 Product 2 Product 3 Product 4 Figure 5. Comparison of stiffness ratios for a series of commercial products labeled as "soft" and :'hard" holding formulations.

O.Q -6.0 -1 O.O •blUi•h •,I•WWWWWWWI (a) Time o.o - •o 4.0 -lO.O 4.0 -lO.O 4Z.Q I•WWW•W•WW•WW•II . •UWI•I•WI c• Time sl (c) Time Figure 6. Comparison of the time dependence of adhesion forces for 100% (a), 80% (b), and 55% (c) VOC hairspray compositions based on the ethyl ester of PVM/MA copolymer.