What should be done if the hair turns green after coloring?

If the hair turns green after coloring, the most effective approach is to use a red-based color to neutralize the green. This outcome can happen due to various reasons, including the interaction of hair dye with underlying pigments or previous colors. The color wheel illustrates that red is opposite green, which means that red pigments can effectively counteract and neutralize the unwanted green tones in the hair.

By applying a red-based color, you introduce the complementary shade that neutralizes the green, helping to restore the desired hair color. This method is based on the principles of color theory, making it the most reliable solution for correcting this issue.

While other suggestions may have some merit, they do not offer the same level of effectiveness in addressing the specific problem of green hair.