PERMANENT WAVING AND PERM CHEMISTRY 119 Figure 14. SFTK data for reaction of single source Asian hair with 0.42M, pH 9.3 cysteamine after reduced time analysis. Figure 15. Comparing experimental reduced time data for single-source Asian hair reacting with 0.42 M, pH 9.3 cysteamine to theoretical models.
JOURNAL OF COSMETIC SCIENCE 120 Figure 16. Reduced time plots for single-source Asian hair reacting with 0.42 M, pH 9.3 cysteamine and ATG solutions. derive expressions that better describe the progression of the perm reaction with time. Until then, curve-fi tting software (TableCurve® by Systat Software, Inc., San Jose, CA) has been used to record shapes of experimental reduced time plots in Figure 16. Confi dence in these experimentally observed relationships (and indeed the SFTK approach itself) is strengthened by both the reproducibility of the data and the fre- quency with which they are found. To further illustrate this point, Figure 17 shows the result of performing reduced time analyses on the previously mentioned experi- mental data for 0.42 M cysteamine solutions as a function of pH (see Figure 8). In Figure 17, the solid and dashed lines represent the two experimental behaviors described earlier. Accordingly, it is seen how experiments involving cysteamine solu- tions with pH 6–9 all appear to abide by the same mechanism identifi ed earlier however, a change is evident when the pH is raised to 10. Moreover, this new behav- ior corresponds exactly to that identifi ed previously for the 0.42 M, pH 9 ATG solu- tion. Therefore, the reduced time method provides a simple and useful means for identifying these different mechanisms, and without this approach, the previously mentioned conclusions would not be evident.
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