Depth and Levels of Color, Oxidative Haircolors
The type and concentration of melanin in the cortex are different in each individual and they determine the field of the hair color (dark, medium, or light). For example, if the eumelanin is concentrated, the hair will be dark in color (black or dark brown); if it is not, the hair will be light (light blonde). In the illustration above you can see how the concentrations of melanin provide different depth of color. The type and concentration of the melanin also determine how long the hair will take to decolorize and what the final tone will be. For example hair with a large concentration of pheomelanin will take longer to decolorize than hair with a large concentration of eumelanin because red is resistant to decolorization.
There are two types of oxidative haircolors: Oxidative without ammonia haircolor and oxidative with ammonia haircolor. Oxidative without ammonia haircolor will not lighten hair. It uses the color of the hair as the base for depth and tone, and simply deposits new permanent color molecules to create the new color. Oxidative with ammonia haircolor decolorizes the hair to create a new base for the artificial color, and deposit new color pigments to produce the new hair color. The lightening action of this type of color is perfect when no more than two levels of decolorization are required.