I'm done with henna, how do I get my natural color back?
I'M DONE WITH HENNA, HOW DO I GET MY NATURAL COLOR BACK?
Henna can't normally be removed in such a way that you return to your original color, but it can be lightened.
If you have only used henna and/or cassia, or if you used some buxus but it faded away, you can safely bleach your hair or use a high-lift blonde dye. Please see the FAQ about bleaching out henna and other plant dyes.
Once you have lightened your hair to about the level of your natural hair, it will still be orange but much lighter orange than before you bleached it (don't try to bleach out all the orange or you'll damage your hair so much it won't hold chemical dyes anymore, and you'll end up cutting it off). At this point you can use a chemical dye on it to tint it back to a non-orange shade of dark blonde or brown. We suggest using a chemical dye 2 to 3 levels lighter than your intended result because, as you've now discovered, henna doesn't lift easily! so the color result you get with the chemical dye will be your starting color (some shade of orange) plus the chemical dye's color. Please strand test before doing your whole head to avoid unpleasant surprises (much darker hair than you anticipated is the most likely unpleasant surprise, but it's also possible your hair will be unable to hold dyes anymore if you bleached it too much).
Another option is to gradually transition off of henna instead of going cold turkey. You can do this sort of gradual transition a few different ways.
You can dye your roots using a demi-permanent dye or temporary color (the kind that says it will wash out in just a few shampoos) in a shade of red or auburn that matches your hennaed length. Each time you touch up your roots with demi/temporary dye after that, use a lighter shade of red/strawberry blonde/eventually blonde, so you transition back as light as you want, trimming off the dark ends as you go. The demi will tend to fade in a month or two so this will help you get that lighter color as long as you don't use the demi on the length.
Or you can do the same thing, but using plant dyes. Each time you touch up your roots, use less of the henna/indigo portions and more cassia, until you are using mostly cassia, then all cassia, and then you can stop. Don't re-dye the length at all (or use just cassia on the length if you wish), and trim off the darker ends as you go.
Another possible option: There are a number of people on the Long Hair Community forum who have successfully removed henna, and in some cases indigo, using repeated, very prolonged applications of color removers like Colour B4, ColorFix, or ColorOops. Please see that forum for full instructions and discussion. There is no guarantee that it will work but may be worth a try. http://forums.longhaircommunity.com/showthread.php?t=85463
For the very patient person, the LHC forum also has information about a method called “honey lightening” that uses special types of honey and distilled water to very slowly and gradually lighten hair. Some people have used it on hennaed hair with good results. It is very gentle to hair but much slower and probably more expensive (lots of honey is involved). http://forums.longhaircommunity.com/showthread.php?t=148
It is very important to STRAND TEST any chemical dyes you wish to use.