Final answer:
If you apply oxidizing hair color on hair that already has metallic hair color, a reaction may occur between the oxidizing agent and the metal in the existing color, potentially causing damage and unexpected color changes.
Step-by-step explanation:
If you applied oxidizing hair color on hair that already has metallic hair color, a reaction may occur between the oxidizing agent and the metal in the existing color. This reaction can cause the hair to become damaged, brittle, and weak. It may also result in a change in the color of the hair, as some metallic dyes can react with the oxidizing agent and produce unexpected colors.
For example, if the existing metallic hair color contains copper, and an oxidizing agent like hydrogen peroxide is applied, the copper ions from the metallic dye can react with the peroxide to form copper oxide. This may result in a green or blue tint to the hair.
It is important to avoid mixing different types of hair color without understanding the potential reactions that may occur. If you are unsure, it is best to consult a professional hairdresser or stylist for guidance.