If you need to colour your hair one colour while adding highlights at the same time, you can do so using the foil method. This will allow you to apply the base colour dye and the highlight colour at the same time, which not only saves time but prevents extra damage to your hair. Keep in mind this process is difficult to do on your own; and if you have little experience with hair dye, you should consider asking a professional for help.
Put on old clothing and wrap a towel around your shoulders to protect your neck against stains. Rub vaseline around your forehead, ears and any other areas the dye might touch during the colouring process.
Divide the hair into the top and bottom layers and use clips to keep the two sections separated. Mix together the hair dye in one bowl and the highlighting dye in another and put on plastic gloves to protect your hands. Have all your supplies at hand. You'll need to work quickly to avoid over-highlighting certain areas and under-highlighting others.
Unclip the top section of hair and divide it into smaller sections with a comb. Choose which sections will receive highlights and which will receive the base hair colour. Start with one section and apply the appropriate dye. Wrap a piece of aluminium foil around the hair and fold the foil in half to hold the section securely inside it. Clip it out of the way and proceed to the next section.
Dye all the sections in the top layer of hair and clip them out of the way. Repeat the procedure with the bottom section. If you are not highlighting the bottom section, apply the base colour dye to the entire layer and do not worry about using foil.
Time the hair dye based on the first section you applied the mixture to. Read the hair dye instructions to see how long to leave the dye in. For a basic box of hair colour off the shelf the time ranges from 25 to 40 minutes. Start timing from the minute you apply the dye and, when the correct time has elapsed, remove the foil.
Rinse out the hair dye in warm water. Apply the conditioner included with your hair dye and allow it three minutes to soak in. Rinse again with warm water until the water runs clear.
Pat your hair dry with an old towel and let it air-dry. Avoid shampooing for 48 hours if possible to let the dye set in. Use shampoo and conditioner designed for colour-treated hair.
Do not wash your hair before dying it. The oil on your hair protects it against the harsh chemicals in dye. Ask a friend for help dying the back of your hair and wrapping the foil around each section.