Anyway, from my personal experience, I learned two tricks that worked for me in order to achieve the desired hair color and fix a bad dye job.
- How to Fade Hair Dye : Mix equal amounts of baking soda and developer (volume peroxide) until you have a thick paste. Apply it evenly to your hair and cover with a plastic bag. Leave it on until the hair is light enough for you. To speed up the process you can use some heat from a blowdyer. Next you'll probably have to re-dye your hair with the right shade (always go 2 shades lighter than the desired one)
- How to Tone the hair: If the hair color is too brassy/orange this is a hack that will not only fix the problem but will condition and treat chemically-damaged hair which is probably the case here: Add few drops of food coloring (Blue to tone orange in brunettes, Green to tone red in brunettes, Purple to tone yellow in blondes) with your deep conditioner or any regular conditioner. Apply generously to your hair and leave it on for about an hour. Your hair will be softer and much less damaged afterwards. After several washes with this pigmented conditioner the unwanted tones will be almost completely gone.