Covering red hair dye with a darker hair color is extremely easy. In fact, the easiest hair-color jobs are those that deposit color to correct or cover an existing dye job. The most important factor in covering red hair dye is color selection. Previously colored hair has a tendency to "grab" or "soak up" color. If you choose a color that is the exact color you desire, you may be disappointed when the color turns out a shade or two darker than you anticipated. To prevent this from happening, choose a color that is one shade lighter than the desired shade.
Pour equal parts of hair color and developer into the color bottle. Close the lid and shake the bottle until the color is completely blended with the developer.
Part your hair directly in the middle. Create a second, horizontal part from ear to ear and across the top of the head. Your hair should now be in four sections. Pin the sections with hair clips. Place a towel over your shoulders to protect your clothing. Put on latex gloves.
Remove the hair clip from one section. Apply hair color from root to tip using 1/2-inch cross sections. Continue applying color until the entire section is saturated. Move onto the next section and repeat the process. Continue until all hair is thoroughly saturated with hair color. Check to make sure that all hair has been covered with hair color.
Wait 20 minutes. During this time, take off the latex gloves, and clean up the color mess.
Rinse with lukewarm water until the water runs clear. Shampoo the hair and follow up with a conditioner. Rinse out the conditioner, towel dry and style as desired.
Color selection is vital. Avoid colors that contain a red base. Colors that contain red bases contain words such as warm, chestnut and mahogany. Ash colors contain a green base which neutralizes red. Words to look for include cool and ash. Always use cool, ash colors to cover red hair color if you don't want to see any red tones peeking through.
Hair color starts to oxidize as soon as it is mixed. As hair color is oxidizing, it continuously gets darker. A medium-brown color may oxidize to the point that it appears black, but it's no cause for concern. Your hair will not turn black as a result of oxidation.
Rub a thin layer of Vaseline around your hairline to prevent the color from staining your skin. If a stain occurs, it will fade within a day or two. If the stain is in a conspicuous location, color remover will remove the stain. You can purchase color remover at any beauty supply retailer.