FACTORS CONTROLLING THE ACTION OF HAIR SPRAYS--I Table 11 Capillary rise of n-dodecane in the fibre bundle S (cm) t (s) Syt (cm • s- •) 2.0 1 4.00 3. ! 4 2.40 4.1 6 2.80 5.0 11 2.27 6.0 14 2.57 7'0 19 2.58 Average 2.77 515 Table 11I Capillary rise of oleic acid in the fibre bundle. S (cm) t (s) S'/t (cm a s -•) !.5 9 0.25 2.0 17 0.24 2.4 30 0.19 3.0 42 0.2l 3.5 56 0.22 4.0 76 0.21 4.4 94 0.21 Average 0.22 Table IV Capillary rise of resin D in ethanol solution rising in the fibre bundle under saturated conditions S (cm) t (s) Sa/t (cm a s -•) 1.6 2 1.28 2.1 4 1.10 2.7 6 1.20 3.3 9 1.21 3.6 10 1.30 4.2 14 1.26 4.7 18 1.22 5.2 23 1.17 6.2 34 1.13 Average 1.21

516 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Surface tensions and viscosities (at 25øC) of fluids used to measure the 'effective capillary radius' of the fibre bundle Surface tension Viscosity Fluid (mN m -x) (centipoise) n-Dodecane 25.4 1.35 Oleic acid 32.5 25.6 Resin D solution 21.4 2.70 Table VI Values of the 'effective capillary radius' deter- mined with various fluids Fluid r X 10* (cm) n-Dodecane 2.9 Oleic acid 3.4 Resin D solution 3.1 Fig. 8 shows the plots of $ against t • for several resin solutions and for ethanol itself. There is considerable deviation from linear behaviour. The apparent rate of rise is decreased with time owing to evaporation of the solvent from the fibre bundle and the subsequent rise in the viscosity of the solution. The viscosity is not constant throughout the system. In contrast low vapour pressure liquids do exhibit the expected linear relationship between S and t • as shown by n-dodecane and oleic acid in Fig. 9. Similarly, when evaporation of solvent from the resin solution is prevented the linear relationship is once again obtained. Fig. 10 contrasts the behaviour of hair spray resin D in ethanol solution under conditions of free evaporation and under saturated conditions respectively. Recently the author has shown that the wicking of volatile solutions of polymers in a small bundle of hair fibres is described by the equation (19, 2O)' S ,), • r ? cos 0 mr • p [1 - exp[.- 4•c:at'!'][' - 8n,•c • '•_1 (5) ar?cosOmr2pC•[ - [(4½ - p)•q •3 •xp[- 4•½ •!' ] + 5•n•-•(• 2 3• L expt h3g J- mr•p I