My experience with henna

Multiple colour removers and multiple bleachings are the only way to get henna out. It will be easier to just cut it off TBH
Henna is truly permanent, if you have many layers even a full bleach won't lighten it a great deal.
People who have had success removing henna with colour removers keep the product on for a lot longer than suggested, around 3 hours. i have never tried this, and suspect that the chemical reaction would have ended long before. My mantra with colour removers is keep it covered, keep it warm (wave a hair dryer over it) and keep it on for the full hour. Clarifying well beforehand will ensure you get the best possible results, and you need to rinse for at least an hour (not necessarily all in one sitting)

I love henna! I've been using it enthusiastically for over ten years now. About six months ago I fancied adding some splashes of unnatural colour to my hair, to take me back to my bright hair days of 18 -20 years ago.

So I got my bleach (not very strong) and slapped it on some bits of hair (ignoring the horror stories on the internet and the warning on the box 'Do not use over henna'). Then I waited an hour to see if my hair would burn off. It didn't. It only lightened slightly so I slapped it on again and it eventually lightened to a pale-mid ginger, pink, orange, tinned salmon colour.  I do NOT recommend bleaching twice, I'm lucky I got away with it.

Anyway I put Directions Flamingo Pink, Violet and Atlantic Blue in thin streaks and the rest is henna. Despite the orange-pink base the colours have come out really strong and bright and very close to the colours in the dye tub.

That's my experience of bleaching over henna- it can be done but it's risky. I used loads of coconut oil before I bleached and the condition of my hair is fine. Just be careful and try it on a small section first.

My experience is very similar to Hazydaisy.  I used bleach on some strands for highlights, the top half of my hair lightened alot more (obviously because of the build-up). I bleached again on the lower half and it was light enough to dye but still had an orange tinge. The condition of my hair is still good, maybe because the years of henna have made it so healthy.  I have used directions cerise and violet and it's turned out great, I have also cut a couple of inches of hair around my face shorter and this lightens more easily. One thing I am looking at is a reverse Ombre, an interesting look that might work on hennaed hair.

Hello all, thought I'd post an update on my progress.  I used Colour b4 a second time after using a clarifying shampoo and left it on a bit longer.  This time it lightened up the darkness from many layers of henna a bit more but it is still as red as ever.  I have the utmost respect for the power of henna even if I can't get rid of it lol!

A note about the warnings for henna users - the only reason for the warnings is that the cheaper henna often found in shops contain metallic salts, which can cause issues if you try to use dyes over it.  However the pure body quality henna powder does not contain metallic salts so it's fine!    The only issue being the coating of henna on the hair is virtually impossible to remove!

So at this point I may do a bleach bath next, I'm not really sure.  I actually kind of like this lighter red hair so maybe if all else fails I'll just go back to henna lol.  It covers greys and is healthy for my hair - I was just so tired of red.  I have daydreams of dark blonde hair with blondish highlights, is it even possible?  I just don't know.......

Well yes - henna is very difficult to remove but not impossible since me and blu-one have both bleached it out with success. Success, that is, if you want to put strong bright colours over it. If you want blond it might not happen, you'll likely be left with an orange-pink tinge.

Yeah not looking to completely bleach out my hair so still havent quite figured out what to do.  I'm wondering if I just use a dark blonde over the top of everything what it would do.  It wouldn't get rid of the red but maybe tone it down a bit, maybe...  The new growth since my last henna won't quite match as it will not have the red underneath.  But maybe it'll blend ok? 
I'm going to test a strand of red with blonde permanent dye today and see what happens.

Ok tested a strand of hair that is still very red from the henna - used a dark blonde seven level dye.  All it did was darken the hair and it's still as red as ever. 

Yep, as Hazydaisy has said "if you want to put strong bright colours over it"  - not blonde.  I just don't think thats going to work for you.  You'll have to decide on a darker or more vibrant colour to use on your hair. 

Ok do you think a light brown could work?  It has been a year since I hennaed and the front of my hair around my face is layered - so I could just highlight that part blonde since the henna is grown out there. 
I've used Colour B4 twice and a quick bleach bath once, I'm not sure what to do next.  Maybe I'll try one more bleach and see what colour I'm left with.  Probably just a lighter version of orange!  I'm not sure what colour to use when I dye it again, maybe just a light warm brown or dark blonde to even things out a bit.  The top where the henna is grown out is light mousy brown  and doesn't match the rest of my hair at all.

If all else fails I still have a couple packs of henna powder....

Aaah! after all the work you've just done on your hair, not to mention the damage, you are'nt going to go back to henna are you?.  Some sort of semi permanent brown could work could'nt it?. I've only done highlights, not my whole head, but you can cover it with pinks, purples, a wine or burgundy etc. Maybe just for now until you decide what you want to aim for in the future when your natural colour grows in.  If you go back to henna it will have to be a commitment, so think carefully.

No I'm not PLANNING to go back to henna, it's just an option if things go badly LOL. 
Update on my hennaed hair dilemma - I gave my hair another bleach bath using 6% developer and left it on for 20 minutes.  As I thought I ended up with a lighter and even brighter orange.  This is as far as I'm going to take lightening as I think even if I left bleach on until my hair melted it would still melt to a pool of orange.  (The Strength of henna still amazes me). 

So anyhow, I had a couple boxes of Nice and Easy non-permanent 8-wash hair colour and used that, but it barely subdued my bright orange head.  I then used my backup bottle of Superdrug washout colour in True Chestnut and once again it barely did a thing.  I don't have any Adore left on hand which I know would work and couldn't wait so I stopped at Sally's today.  The majority of their temp colours are bright and funky which really isn't me, but I found one in warm chestnut by Osmo.  I just used it a little while ago - it says to leave it on 10 minutes max and I'm sure I went over that time just trying to get it applied.  But I was shocked after I washed it out - it covered my hair completely and darkened my hair quite a bit.  It's so dark and even that I can hardly believe this is going to wash out?  Has anyone else used the Osmo Colour Revive?

I'd hate to have done all this work on my hair to lighten it only to accidentally darken it again!

If you want to counter the orange, you need to use blue. It is the opposite colour so will neutralise the orange into a cooler more neutral shade.
To lighten the current colour shampoo with strong shampoos, I apply dandruff shampoo to barely damp hair, cover and heat with a hairdryer. rinse with hot water after half and hour. It pulls a lot of colour out.
Always strand test with new brands/colours!

I have the awkward problem of the top third of my hair that there is no henna on it - so it's dull and drab and wouldn't look very nice in blue.  The bottom 2/3 was a bright bozo the clown orange - So I was desperate to cover it up!  I don't mind the dark brown from using Osmo Colour Revive at the moment - but it covered my orange so intensely and completely it's hard to believe it's just a temporary colour.  I double checked and it is peroxide and ammonia free so I'm thinking it will wash out when I'm ready.....I'm wondering has anyone else tried Osmo Colour Revive?  It was expensive, over £10 for a bottle and I used almost all of it.  But like I said, I was desperate and embarrassed of my orangeness.   

I will probably go back to using Adore for a while until I sort my hair mess out.  While the Osmo worked well the colour choices are limited and the price awfully high.  Though I still find it hard to believe the max time to leave the dye on is 10 minutes?!  I can't understand how this product works so quickly.

She just means to put the blue on the orange though. To tone it.

I've not heard of the osmo dye before. Looking it up, it seems more like a touch up I between salon visits. I don't think it's any stronger than other direct dyes, all direct dyes have a 10-30 min leave on time stated. Wash them off in that time and they will have worked. We just tend to think they don't last as long that way and won't be as intense. This is very dark, so probably just seems very intense when you're used to lighter. No idea though really, I'm just guessing.