Pre-soften stubborn grey hair if you think it's going to put up a fight. It's usually larger patches of grey hair around your front hairline that are going to give you the most grief, so show that grey who's boss by soaking a cotton ball with 20-volume peroxide and generously dabbing these areas. Let the peroxide sit on the grey hair for five to 10 minutes, then rinse thoroughly.
Divide your hair into four equal sections. Part the hair from the the middle of the front hairline to the middle of the back hairline. Now make a part from the tip of one ear, across to the tip of the other. Use hair clips to keep the sections from getting in your way if necessary.
Mix your black hair color in a color bowl, following the product's directions, with 20-volume peroxide. Usually you'd only need 10-volume peroxide to go darker like this, but that stubborn grey hair needs the extra muscle power of the 20-volume peroxide to open up that tough cuticle and sneak the color in.
Tackle that stubborn grey hair in the front first. Slip on your latex gloves and generously apply the black hair color to all of the front hairline first, from the front of one ear, to the front of the other. Now go back and apply the color, from root to tip, all throughout both of the front sections. Really lay it on thick -- if you see any stubborn grey hairs sticking up out of the color, give it another coating.
Apply the hair color to all of the hair in the back two sections from root to tip. When all your hair is coated in color set a timer for 30 minutes.
Take another sneak peek at the front hairline. If you see any stray grey hairs, dab them with the color brush to push them into the color. Really stubborn grey hair can sometimes stand up in protest during the color application so keep an eye on any unruly strands.
Once the time has elapsed rinse the color from the hair. Continue rinsing until the water runs clear and all the excess hair color has been washed away. Apply a conditioner for color-treated hair, let that sit on the hair for a minute, then rinse thoroughly. Bye-bye grey, hello black-haired beauty!
To avoid the dreaded ring around the hairline from color staining your skin, apply a thin layer of petroleum jelly under the front and back hairline. Just be sure not to get any of it on your hair, or you'll end up with grey splotches where the jelly sat.
Even with pre-softening, some grey hair still has a mind of its own. If yours still doesn't want to play nice, wrap your hair -- with the hair color on it -- in a plastic bag. Put a diffuser attachment on the end of a blow dryer and aim the warm air all over the bag. The heat will help open up the hair's cuticle farther and allow for more color penetration.
Grey hairs not completely submersed in the hair color may not take the color properly. That's why it's so important to make those rebellious hairs lie down and behave.