Effects of Residual Chlorine in Tap Water on Color Fading of Dyed Hair

Abstract

It has been reported that residual chlorine in tap water damages hair, but its effect on the color fading of dyed hair remains unknown. Therefore, this study investigates the effects of residual chlorine on the color fading of dyed hair. Dyed hairs in three different colors were repeatedly washed in a shower with or without shampoo using either the residual chlorine water or purified water from which residual chlorine had been removed. Further, the change in the color difference ⊿E^* over time was examined. In all colors, the ⊿E^* increased when showered with the residual chlorine water and the purified water, but that of dyed hair was larger when showered with the residual chlorine water than with the purified water, suggesting that residual chlorine contributes to color fading. The contribution of residual chlorine to color fading was determined from the behavior of ⊿E^* under each test condition. The results suggest that, depending on the color, the contribution of residual chlorine is comparable to that of shampoo, which is generally considered to be a cause of color fading. In the chromaticity diagram, color fading caused by residual chlorine and shampoo showed a similar hue change. This indicates that, like shampoo, residual chlorine promotes the elution of dyes. These results demonstrate that residual chlorine is one of the causes of the color fading of dyed hair and that washing hair with the purified water can prevent the color fading of dyed hair.