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Follow the instructions that came with the dye for mixing and developing it. Wear gloves the entire time and keep a towel secured around your shoulders to protect your skin. To protect the dye from staining your face, apply a thick lotion or a layer of petroleum jelly around your hairline before you begin. You can use a hairdresser's cape instead of a towel if you have one. Start in the front of your hair and work with one section of hair at a time. Pull a chunk of your hair out of the clip and apply the black dye to the section, taking care to saturate your hair with the dye from root to tip. Use bobby pins or hair clips to pin the finished sections out of the way so you can easily get to the rest.  If you have thick hair, you may need to separate the sections into smaller sections that are about 1 inch (2.5 cm) thick. You can twist each completed section into a mini-bun and pin the sections like that, if you like. Pin the sections up as you finish them so that they are kept away from the bottom layer of your hair. Follow the directions included with the box of dye and leave it on your hair for the recommended length of time. Keep a towel wrapped around your shoulders in case the dye drips onto your skin. As soon as you finish applying the dye, set a timer for the time span the product recommends. Before you rinse the dye out, gather the bottom layer of your hair and secure it in a low ponytail. This will keep it out of the way as you finish with the top section. You will need to lean forward and put your head under the water stream to rinse out the dye. Once you’re leaning forward, remove the clips and bobby pins and start rinsing your hair.  Don’t get the bottom layer of your hair wet and keep it out of the way. It may be easier if you have a friend help you with this part. Rinse your hair until the water runs clear. Squeeze out the excess water, then put a towel in between the top layer and the bottom layer. Flip your hair over and it will fall on the towel without touching the bottom layer of your hair. Squeeze out as much water as you can and towel dry it gently. Blow dry the top layer of your hair as you normally would.  Keep the bottom portion of your hair in the low ponytail throughout this process. After your black layer is completely dry, clip the hair up again so that you can move on to dyeing the bottom layer.
Prepare the dye and your work area. Pull a chunk of hair out of the clips and apply the dye. Finish applying the black dye to your top layer. Rinse out the black dye. Dry your top layer of freshly dyed black hair.