can you dye a natural colour over a bright colour?

If you put a darker brown over it then i imagine it would cover it up. But if its lighter it might not work so well.

mmmm, i imgaine if i let it fade loads then a dark brown would cover it, i wonder what that would look like when that faded though, probably a strange kahki toned brown 😛

As a previous blue-head that had to dye my hair a dark brown for a job interview (bah, didnt get the job :/), I can vouch for the khaki/green tinted brown 🙁 Its not pretty either....

If you add a little red or orange you can neutralise it. See the colour wheel for more info.

http://www.hairdyeforum.com/index.php?topic=1414.0

I've heard some people say that ketchup can stain your hair so maybe try a little of that on the turquoise. It'll make it a yucky shade of brown but obviously a good base for brown dye to go over.

As a previous blue-head that had to dye my hair a dark brown I can vouch for the khaki/green tinted brown 🙁 Its not pretty either....

Yes indeed. If I wear to do this again (go from blue to brown) without killing my hair this time then I'd stick directions mandarin on it to neautrise and add warmth then do a dark brown. Instead of colour b4 (failed) bleach (failed) brown box dye (killed my hair)