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Damaging Effect on Treated Hair Using Microscopic Techniques

Shiori Kawaguchi

University of Rochester, Department of Chemical Engineering

Introduction:

Many people care about how they look, and one of the most common and cheapest cosmetic product used is bleaching or permanent hair coloring agents. The texture of hair drastically changes when those products are used. I thought it would be interesting to visually see what they can do to hair on the micro scale. Bleached and colored hair and just colored hair were compared to untreated hair by examining the cross-section and the outer surface. Six microscopic techniques were employed to analyze the effect of the hair products.

Samples and Preparation:

All three samples were Asian hair. Brown hair was simply colored while pink hair was bleached, then colored. Black hair was never treated with any hair products. The samples were nicely cut into 1cm length with a sharp blade and put on SEM sample stubs with carbon tape. The sample stubs were then coated with gold to make them conductive for SEM imaging. After gold was sputtered normally, they were tilted in the chamber and sputtered again so that the cross-sections would be also conductive.

Methodologies:


Imaging and Results:

1. Outer surface of the samples

Untreated
(Black)
Colored
(Brown)
Bleached and Colored
(Pink)

Fig .1 Outer surfaces of SEM images

Figure 2. Light microscopy images

Usually, you can feel the difference of hair just by touching. Roughness of the surface was expected microscopically from bleached and colored hair and seen in Figure 1. Layers of the bleached and colored hair (pink) looked like they were peeling off. Even the light microscopy showed the roughness of the pink hair in Figure 2. Between untreated (black) and colored (brown) hair at 3.67kx the layers on the brown hair seemed more filled compared to the black hair. Dye may have closed up the gaps, but it could also be the result of the angle that images were taken. Surprisingly, the brown hair did not show as much difference as the pink hair. It seemed that bleaching was damaging the outer surface more than coloring.

2. Cross-section of the samples

Untreated
(Black)
Colored
(Brown)
Bleached and Colored
(Pink)

Figure 3. Cross-section SEM images

Figure 4. EDS analysis

Unfortunately, no significant difference was found from cross-section area between the samples as seen in Figure 3, although there maybe a dent on the black hair, but not on the others. In the EDS analysis the brown hair had a peak around 1.5 corresponding to aluminum from the stubs. On the other hand, the peak from the pink hair around 1.0 was probably sodium salt from the pink dye.

Conclusions:

Severe outer damage was seen from bleaching, but not so much from coloring. The hair layers started peeling off microscopically, and it was physically felt. No damage was observed on the cross-sections while possible sodium dye was detected from the bleached and colored hair. This could be the result of the dye being trapped in the hair when bleaching was used.

Acknowledgments:

I would like to thank Brian L. McIntyre for helping me patiently throughout this project. I could not have done it without him.

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