Dyeing and Fading of Human Hair Translucent Keratin Film by Semi-Permanent Hair Colors

The dyeing and fading of semi-permanent hair colors were examined using transparent human hair keratin film. Among four kinds of commercial semi-permanent hair colors, the translucent keratin film was significantly dyed with three products. The coloring was dependent on dyeing time and increasing dyeing number, and the latter was important to gain deeper dyeing. When the film was dyed by two different products and analyzed by a spectrophotometer, spectra of the average absorbance were independent of the dyeing order. Compared with the dyeing of oxidative hair color products, no significant formation of cysteic acid was found in the films dyed with semi-permanent hair colors. When the dyed films were immersed in distilled water and tap water, the fading by tap water was faster than that by distilled water. The addition of EDTA to the tap water suppressed the color fading, whereas the addition of CaCl 2 to distilled water caused the fading, indicating that metal ions will be closely related to the fading by water. The fading was also observed when the dyed films were exposed to artificial light （ 300 ─ 2500 nm ） using a solar simulator. The fading was conveniently measured and the rate of change indicated the difference between the products. These results suggest that translucent keratin film will be useful to develop damage-free, anti-washout, and less-photofading hair color products.