Adding highlights or creating multiple layers of colour in your hair requires foiling. The foil stops dye from bleeding into another section of hair and simplifies the dyeing process. To foil the hair with colour, you must work each hair section separately. The easiest method for building layers of colour begins with separation of the hair and stacking layers from beneath. This method easily adapts to suit any style or layers of colouring.
Part your hair at the part line you normally wear, whether in the middle or to one side. This provides you a clear vision of how the applied colour will appear with your natural hairstyle.
Place your comb behind your left ear and comb the hair forward to create a vertical part line. This line separates the side-front section of hair from the rear section.
Place your comb behind the right ear and create the vertical part line. Your hair should now show three sections---front ride side, front left side, and rear.
Beginning with the side-front section of your choice, lift the top portion of hair that you will not dye with the underside. For example, if you're dyeing your hair blonde on top and brown beneath, lift the blonde section.
Secure the top portion of hair to the top of your head with a hair clip. This leaves the underside of your hair exposed.
With the foil behind the underside of your hair, apply the dye and wrap the foil closed.
Repeat steps 4 through 6 with the rear and opposite side-front sections of hair.
Remove the hair clip from the first section of hair, allowing the top portion of hair to lie over the foil.
Apply dye to the top portion of hair and wrap in foil.
Repeat Steps 8 and 9 with the rear and opposite side-front sections of hair.