What is the primary function of hydrogen peroxide in hair coloring?

The primary function of hydrogen peroxide in hair coloring is to lighten hair. When used in hair dye formulations, hydrogen peroxide acts as an oxidizing agent. This chemical reaction lifts the cuticle of the hair shaft, allowing the dye to penetrate and alter the natural pigment. Specifically, hydrogen peroxide breaks down the existing melanin in the hair, leading to a lighter shade when the color is applied. This process is crucial for achieving both full-color saturation and lighter tones in hair color applications.

While it is true that hydrogen peroxide can sometimes play a role in other formulations, such as in conditioning products or products aimed at adding shine, those are not its primary functions in the context of hair coloring. The key takeaway is that hydrogen peroxide is essential for lifting the hair's natural color and achieving the desired lighter results in hair dyeing.