I've been coloring my hair with Natural Instincts Cinnaberry (and occasionally Rosewood or Malaysian Cherry) for about 15 years. I haven't really seen my natural hair color in all those years but the last time I got a look, it was a light to medium ash brown. I'd estimate that now I have about 30-40% grey which the Natural Instincts covered completely.
I wanted a change so I decided to try to get back to a dark ash blonde. About a month ago I used Color Oops twice (waited a day between applications). It faded the color a bit but the red was still there. I then used Color Zap - a much stronger product, in my opinion - and it worked much better except without thinking I applied it all over. My roots came out a yellow/orange, and the rest was much lighter but still had some red. I applied a semi-permanent Champagne (level 7 with a neutral base) and the result was close to what I wanted but still the ends were darker than the roots - actually the color of the roots was exactly what I was shooting for.
About a week later I went to a salon for a haircut and the operator was confident she could get my hair close to the root color all over, and blend it so I wouldn't have two-toned hair. Well, she got it closer still but the stubborn red would not go away! She suggested I wait a couple of weeks and come back and she'd 'try again'. I'm not sure I like the sound of that, plus I honestly do not have another $80 to spend.
Amazingly, after all this my hair is in good condition. The operator said it was "stressed" but not really damaged. I've been conditioning every 2-3 days and it's in good shape. Right now the top 1.5 inches are a beautiful soft neutral blonde - I'd say Level 6? and the rest is a light reddish brown. I know 'color does not lift color' and I'd have to bleach the shaft before I could get the ash/neutral blonde I want. I don't want to do an all-over bleach, so I was thinking about doing highlights instead. I'm not that proficient with foils but I do have a cap and before I went red I frosted my hair for years with no problems. I think it would be safer and less damaging to do a 'frosting' and tone with a Level 7 or 8 neutral medium blonde to get an all-over effect than to do a whole-head bleaching. I was also thinking of adding a bit of red/gold corrector to the color. In the past I'd used Loreal Drabber and it made the color a little more ashy with no brassiness.