ALIGNMENT CONTROL AND SOFTNESS CREATION IN HAIR 29 more so, after the GG treatment is evident. So, as described by Zuidema et al. (7), this would indicate the higher setting ability of these two technologies. If the relaxation rate is constant at strains of 1%, as described by Feughelman et al. (9), then the effect of the control treatment and the GG treatment on the initial relaxation, from T = 0 to T = 2 min, is also apparent. In the case of the control treatment, the most likely explanation for this effect is due to the breakage of ionic bonds in hair caused by the low pH value of 3.7 of the formulation. Although the GG treatment also has a pH of 3.7, clearly the presence of GG further increases the effi cacy of this formulation. The further signifi cance of the result for GG is that the increased relaxation rate means less time is needed for it to be effective and thus this fi ts within a realistic timeframe for a typical grooming procedure. Combined with the increased relaxation brought about by GG overall, the effectiveness of this agent in setting the hair is evident. EVALUATION OF INITIAL ELASTIC MODULUS Consumers typically determine the softness of their hair under ambient conditions, as well as during the treatment phase when the hair is damp, and the pliability of the hair fi ber itself was also identifi ed as important to the perception of softness, from the panel- ists responses previously described. With regard to the typical grooming procedure out- lined in Figure 4, it was thus considered whether GG could also affect the pliability of individual hair fi bers in addition to its effect on alignment. Stress–strain measurements over the initial 0.25% (the initial strain was reduced from 0.5% to overcome the effect of the shift in the stress–strain relationship for hair on moving from high to low humidity) were performed under 20% humidity conditions and the change in modulus before and after treatment was used as an indicator of the pliability change of each fi ber. Figure 6 shows the change in modulus over this low strain region for untreated control, control treatment–treated, and GG-treated hair fi bers, expressed as a relative modulus value. Although the moduli of the untreated and control fi bers did not change with treatment, those fi bers treated with GG showed a 20% decrease in modulus, indicating the increased pliability of these fi bers at 20% relative humidity. Figure 5. Normalized stress-transient plots under high humidity for curly damaged Japanese hair after various treatments. Solid line, untreated hair dashed line, hair treated with control treatment dotted line, GG-treated hair. Each plot is the average of the data of 10 fi bers.

JOURNAL OF COSMETIC SCIENCE 30 NANOINDENTATION AND FORCE MAPPING BY AFM After treatment with GG, the changes in physical property of hair indicated that some modifi cation of the hair components had taken place. To investigate this further, and at- tempt to elucidate which subcomponent(s) of hair may be affected by GG, AFM force measurements were used. In Figure 7A, a force map of an untreated hair section, taken from the root, shows the cortex CMC as dark lines among the lighter cortex cells. This contrast between the CMC and cortex cells is lost, however, in images of the highly dam- aged tip region of curly damaged hair (Figure 7B). After treatment with GG, similar regions of the hair again show strong contrast between the CMC region and the cortex cells (Figure 7C). The control treatment did not show any signifi cant effect (data not shown). Nanoindentation measurements performed on the cortex CMC confi rmed that the modulus of the cortex CMC was higher in the damaged tip but had recovered and was indeed softer than that of the undamaged root, as shown in Figure 7D. Figure 7. Young’s modulus maps of hair cross sections after various treatments, (A–C), and comparison of Young’s modulus for the cortex CMC region of each cross section (D). Figure 6. Relative initial modulus results for curly damaged Japanese hair after various treatments, under dry (20%) relative humidity conditions (N = 5).