The Reaction of Oxidative Hair Dyes in Cuticle Layers

Abstract

The mechanism of oxidative hair dyes (permanent hair color) in cuticle layers of human hair was studied. In general, it is considered that the oxidative hair dye deposits monomer into the cortex, and is polymerized with coloring in there. It was confirmed that not only cortex but also cuticle layers were dyed with the permanent hair color, through observation with the thin crosssection of the dyed hair. There were exogenous metals in the cuticle layers from tap water, etc., and the transition metals increased the dyeing and decreased the bleaching. It was thought that the activity of oxidation reaction with hydrogen peroxide was increased in the cuticle layers, and permeability to the cortex was decreased. Furthermore, TEM findings suggested that the oxidation hair dyes mainly reacted in the β-layer/δ-layer interface in the cuticle layers, unevenly distributing the metals in the β-layer of cuticular CMC.