Damaging Effect on Treated Hair
Using Microscopic Techniques
University of Rochester,
Department of Chemical Engineering
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.
- Scanning Electron Microscopy (SEM) Imaging: Imaging technique which captures the morphology and the surface topography of the samples.
- Gold Sputter Coating Preparation: In order to use SEM, non-conductive samples must be made conductive by sputtering a thin metal layer, which prevents charging.
- Backscattered Electron (BSE) Microscopy Imaging: Imaging technique which gives general elemental information of the samples in a contrast picture.
- Energy Dispersive Spectroscopy (EDS): Analytical technique which is used to identify elements within the samples.
- Light Microscopy: Traditional optical microscope
- Colorization: Photoshop was used to colorize some images to make them look visually appealing.
Imaging and Results:
1. Outer surface of the samples
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
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.
I would like to thank Brian L. McIntyre for helping me patiently throughout this project. I could not have done it without him.