Answer:
Dying hair when using two completely different colours is never easy. Some times when people do dye their hair such drastic colours (though it doesn't seem that way) end up with a completely different hair colour to the one they wanted. To dye your hair a light colour such as black to blonde bleach is used because you have to strip the hair colour etc. The best thing you can do to make sure your hair stays in good quality and doesn't get ruined is to consult your hair dresser they will be able to tell you everything you need to know to get the hair colour you want and its the safest option. Its always better to be safe than sorry.