2010 TRI/PRINCETON CONFERENCE 155 cream, then exposed to UV using parameters from Table IV below. After exposure the zinc oxide and jojoba oil-treated tresses had barely perceptible color loss compared to a commercial control claiming to prevent color loss, which had very distinctive and percep- tible color loss (Figure 5). AFM RESULTS FOR ZINC OXIDE AND JOJOBA OIL Hair tresses were evaluated using atomic force microscopy before and after exposure to UV for 7 days (see Figures 6a, b, c, and d). The hair samples were imaged by two different types of microscopy, atomic force micros- copy and scanning electron microscopy. For the most part there is a great deal of overall agreement of the morphology of the hair obtained by the two techniques. Where a feature Figure 5. (a) Exposed area on hair tresses treated with commercial control: Very distinctive and perceptible color loss (b) Exposed area on hair tresses treated with zinc oxide and jojoba oil: Very slightly perceptible color loss compared to commercial control. Figure 6. (a,b) Untreated control. (c,d) Tress treated with zinc oxide and jojoba oil. Table IV UV Exposure Parameters Settings Hair Program 313 nm light, no water Irradiance - 0.35 W/m2 @ 340 nm Panel temp 60°C, 168 continuous hrs European, bleached Colored with Couleur Experts 6.6 Bright Autumn by L’Oreal
JOURNAL OF COSMETIC SCIENCE 156 such as the scales or small particles that may be the zinc oxide was found by one tech- nique, it was typically seen by the other. Subtle changes in the topography of the hair may be seen by comparing the line profi le before and after treatment of the hair with zinc oxide and jojoba oil (Figures 6b and 6d). The small differences in the profi le are due to the addition of zinc oxide to the hair surface. These differences suggest a rather good distribution of the zinc oxide without gross clumping of the material and with a very small effect on the topography of the hair. In most cases, the treatment is not thick enough to obliterate or cover over the individual scales. The treatment does increase the roughness of the scales by deposition of the zinc oxide on a nano scale, but panelists feel the effect of the jojoba oil, and overall surface roughness is relatively unchanged. The addition of the zinc oxide then allows protection of the hair from UV damage and color loss protection by light-scattering mechanism. Distinctive domains of zinc oxide are ev- ident in areas where the hairs touch or overlay on the hair fi ber surface even after exposure to UV light. The hair, as tested by panelists after UV exposure, still maintains a natural, uncoated, and non-greasy feel. During the UV exposure, the hair tresses were clamped so the middle was exposed, and the top and bottom were covered and not exposed to UV the whole tress was exposed to 50°C temperature during the duration of the test. The top and bottom protected portions of a single hair tress were compared to the middle exposed area for average surface roughness and peak to valley height. Surprisingly, the mid- dle exposed cuticles did not appear uplifted or damaged after 168 hrs of continuous 313λ nm at 50°C. Indicating the middle area treated with zinc oxide not only offers color protec- tion but additionally offers hair surface damage protection. See Figures 7a, b, and c. The zinc oxide does not overshadow the treatment. By having a fi ne distribution of zinc oxide across the hair shafts, color loss protection and UV damage protection are obtained, without negatively impacting aesthetics. The hairs still feel and look natural as observed by expert panelist. The treatment benefi ts of the zinc oxide and jojoba oil were observed across Caucasian, Latin, and damaged bleached hair types and would offer benefi ts across all hair types. SEM ZINC MAPPING RESULTS FOR ZINC OXIDE AND JOJOBA OIL SEM images show the morphology of the hair and the treatment distribution. In this series of images we used bleached, dyed hair tresses treated with zinc oxide and jojoba oil, then exposed to UV. Due to atomic number contrast, the zinc oxide material appears brighter than the hair. X-Ray mapping shows the zinc distribution for the zinc oxide materials. Phase maps, in which pixels with similar spectra are grouped together, show two phases (hair and background) for the control samples and three phases (hair, back- ground, and zinc-rich) for the zinc oxide samples. Overlays of the zinc-rich phase maps Figure 7. (a) Top covered. (b) Middle exposed. (c) Bottom covered.
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