ALIGNMENT CONTROL AND SOFTNESS CREATION IN HAIR 25 naturally curly hair collected from a Japanese female were incorporated into straight tresses to various levels and each tress was assessed by blindfolded volunteers (Figure 2A). Clear changes in the alignment of the tresses can be observed as the level of unruly curly hair increases. Figure 2B shows the results of the softness perception test a clear trend in the rating for these tresses was observed, with the tress containing 20% unruly hair assessed as having the lowest softness. This result clearly shows the effect that even a small number of ir- regular hair can have on the overall perception of hair softness and also shows how impor- tant fi ber alignment is to the feeling of softness. Figure 2B also includes the assessment of a tress containing 20% unruly hair (low softness feeling) after treatment with GG. The softness perception for this tress was much higher than that for the untreated 20% tress, with the treated tress being judged somewhat similar to the 5% unruly hair-containing tress. To support this assessment, a Kendall’s coeffi cient of concordance test was per- formed (see the Appendix). Table III shows the rank order evaluations from each judge and the results of the coeffi cient of concordance test, as calculated from equations (1–3). A value of the coeffi cient of concordance, W, of 0.76 was obtained, which indicates good agreement between the judges. Using this value of W, and since both the number of judges, p, and the number of variables, n, were large (15 and 6, respectively), a Friedman distribution factor, χ2, of 57.0 was calculated [equation (3)] at (n − 1) degrees of freedom, it was thus established that this result was statistically signifi cant (p 0.001). Close ob- servation of the treated tress in Figure 2A also showed that the hair bundle was visually well aligned and had fewer hairs projecting from the bunch, further indicating that the fi ber Figure 1. The generation of misaligned hair in an otherwise healthy tress by repeated damage treatments: (A) healthy Japanese tress and (B) same tress after 1× perm and 5× bleaching/shampooing/conditioning cycles.

JOURNAL OF COSMETIC SCIENCE 26 shape was indeed adjusted by the GG treatment. Curl radii measurements were again implemented, this time for the treated hair, and a mean curl radius of 33.3 ± 23.8 mm was determined. This value was intermediate between the values of 56.6 ± 22.0 and 21.7 ± 17.9 mm measured for the curl radii of straight and curly hair, respectively. The difference in curl radius between the curly hair and GG-treated curly hair was found to be statistically meaningful at the 99% confi dence level (as determined by the Student’s t-test), again an indication of the straightening effect of the treatment. To deepen the understanding of the mechanism behind the improvement in alignment and softness brought about by GG treatment, physical measurements on individual hair fi bers were carried out. In this regard, it was considered important to connect the percep- tion of softness experienced by consumers to a realistic stress range for measurement. The fi rst step in doing this was to ask the panelists to describe how they felt softness when touching their hair, in an open answer format. Analysis of their responses identifi ed “smoothness during touching or fi nger combing” as dominant, with “ease of combing/ less snagging during combing” and “less bounce or stress when I hold or bend” judged equally in second place. These answers, therefore, highlighted alignment and the fl exibil- ity of the hair fi ber itself as important factors, respectively, and indicated that consumers are aware of such points. To estimate the load required to just straighten and align unruly and curly tresses, a force meter was used to monitor the loads experienced by such tresses during typical fi nger combing and bunching actions. This arrangement is shown in Figure 3. A range of values between 0.3 and 5 g per fi ber were recorded. In correlation with simple stress–strain measurements on single hair fi bers under high ( 95%) humid- ity con ditions, carried out in preliminary experiments (data not shown), this upper load limit of 5 g was found to correspond to strains of 0.5%, a value that was estimated to be Figure 2. (A) Tresses, made from straight tresses with additions of varying levels of unruly hair, used for softness evaluation, and (B) softness evaluation results for these tresses.