Cruella de Vil loved spots so much that she was willing to kill for them. But brassy spots? No one wants them, not even you. It's best to tone those brassy mistakes down and forget they ever happened. A little bit of color and a little bit of developer will get you well on your way to an even color job.
Choose a color that is the same level of lightness or darkness as your hair or just a bit darker. Don't pick anything that will lighten your hair as it will only intensify the brass. Now, if you want to bleach it all out, you can. But if you want to stay about the same color minus the brass, keep it the same level. Also, pick out a color that counteracts orange and yellow. Colors that do this include dyes with beige and neutral bases. Stay away from reds and yellows.
Combine the color with an equal amount of 5-volume color developer in a color bottle. Screw on the lid and shake with all your might to mix it.
Put on some gloves -- any nonabsorbent kind will work. Squirt the color onto your hair, working it in with your hands and fingers as you go. Saturate all your hair from root to tip.
Wait 25 minutes before rinsing. Rinse your hair a good while -- about five minutes -- to get out all the color. Shampoo and condition.
If your color is a bit darker than what you wanted, go ahead and lighten your hair with bleach or a hair lightener before toning. Sometimes, the lightener will get rid of the spots for you.
Is your hair ready to fall out as it is? If it's too fragile, don't color it. Signs of fragile hair include hair breakage, spongy or slimy feeling when hair is wet, inability to dry and inability to hold color.