Color blocking is a hair coloring technique that leaves large portions of the hair a different color from the rest. It is a common technique for coloring the bottom layers of a haircut, or for adding blocks of bright, unnatural colors like pink or blue. Unlike highlighting, color blocking is not intended to look natural. It is an edgier hair style. However, you can use the same foiling techniques you use in highlighting to achieve color blocking.
Brush your hair to remove any tangles. Decide which sections of your hair you want to color block.
With hair clips, separate the sections of your hair that you will be coloring. If you're color blocking large sections of your hair, like all of the bottom layer of your hair cut, clip the rest of your hair to the top of your head, out of the way.
Mix you hair color in a Styrofoam bowl. The amount of hair color you use will depend on the brand. Completely read all directions for the hair color before you apply anything to your hair.
Grasp the first 2-inch section of your hair. Take the first piece of foil, and lay the hair over it. Paint the color onto the hair with the paintbrush, starting at the roots and working to the ends. When you have painted the entire section of hair, fold the foil in half over the hair, then fold the ends to keep the color from leaking. If the section is on the side or bottom of your head, pin it in place with a hair clip.
Repeat this process with each 2-inch section of your hair, moving as quickly as possible so your hair is processing for about the same length of time. Leave the color in the foil for the amount of time directed on your hair color package. This time will vary depending on the results you want and on your original hair color.
Remove the foil from your hair sections, and rinse the color out of your hair with water until the water runs clear. Shampoo your hair with a color-protecting shampoo, rinse, and then apply a deep conditioner. Wait five minutes and then rinse out the conditioner. Towel-dry your hair.