Hi wantmorehair,

Debbie has some great suggestions, I have also used L’Oreal Feria Bleach Blond with very good results on 1B color which is very dark brown color,(darkest before black). I apply it to the knots with a straw and this seems to put the right amount on the knots to bleach them well. I dip the side of the straw (you could probably use a pen or pencil) in the bleach then apply to the bottom of the knots by moving the straw side to side and leave it on for about 30 mins. Sometimes I have had to bleach a stubborn system twice.