To cover up red hair dye, try washing your hair with a mixture made of shampoo and food coloring. If this fails to neutralize the red to a satisfactory level, use an ash-brown semipermanent hair color. Use a clarifying shampoo regularly to further tone down any red hues.Continue Reading
Add one or two drops of green food coloring to a bottle of shampoo, and shake the bottle well. Green is opposite red on the color wheel, so it neutralizes the red tone.
Using the food coloring and shampoo mix, wash your hair. If the color is still too red, add another one or two drops of food coloring and repeat. Do not add too much food coloring because this can give your hair a green tint.
After neutralizing the red, apply an ash-brown shade of a semipermanent hair dye. The brown shade needs to be the same color level as the red shade previously used.
Use clarifying shampoo at least once per week because it removes mineral buildup, which makes hair redder and brassier over time. This is especially important if your water is rich in iron, because iron makes red hair brighter.