I have medium brown hair and I have a blonde chunk in the side which is about half way down now because its growing out, I also have a bit of blonde in my fringe, inreally really want to dye all my hair really really dark brown, will th blonde go lighter or will it make the brown be a different colour and that area or will it be fine?
Please help as I'd really like to do my hair tonight ! Thankss
Lizzie

You'll have to be very careful. Very blonde hair no longer has any red in it and the dark brown dye formulators assume that there will be a lot of red present. To counteract the red that they assumed would be there, they add a lot of green pigment into the dye. If you don't add that red back in to the blonde section, the blonde sections will come out with a greenish tinge. You'll have to dye the blonde separately from the brown and add red to the mixture. Either that or dye the blonde reddish and then you can probably dye the whole head. Even with all that, you will see differences where the hair is blonde now and where the hair is brown now. As it fades, the differences will change (they might become less or more pronounced -- your guess as to which).