Right I've got black hair but I wanaa dye it purple my mate put purple over black and you can only tell that her roots are purple so I'm gonaa put blonde it on so it lightens my hair what would happen is I put dark purple over a gingerish blonde :LL

It might work.. but I recommend bleaching your whole head if you want it really purple. Even though its not very good for your hair but you'll get the best results that way. And don't use like a regiular blonde it won't work you need bleach blonde. And even then it might not get as light as you want black is very hard to get rid of. But if you bleach it it'll work.