I have decided to write a fairly detailed review of Colour B4, because there is a lot of mixed messages surrounding henna removal generally, and Colour B4 and henna. I struggled to find any useful informed reviews on Colour B4 and henna - hopefully this will do the trick!

The packaging states that you cannot use CB4 for henna removal. Henna is notoriously almost impossible to remove - it binds to the hair shaft differently from artificial dyes. Furthermore, many dyes sold as 'henna' are not pure, but contain metallic salts, which react very badly indeed with ammonia and bleach and will destroy your hair.

My own hair is naturally a dark honey blonde, with years of highlights on and off. I used LUSH CACA ROUGE 3 or 4 times in the past 4 months and had a very rich, deep and dark henna shade (think Florence Welch). However, I am at heart a blonde, and so have been desperate to return to my usual shades.

As anyone who wants to get rid of henna knows, the general consensus on the web is that you can't, and even that you will have to cut off your hair to be rid of it - but I am here to tell you that you can!

Firstly, you MUST be sure that the henna you have used contains no metallic salts. If you aren't sure, simply pull some hair out of your hairbrush and do a Colour B4 strand test. It is also recommended that you wash your hair twice before using to remove build-up of product etc., which can prevent CB4 from working effectively.

Colour B4 itself will be familiar to anyone who has used hair dyes. You mix together two bottles of substance, give it a good shake, then apply until your hair is soaked. My own hair is above the shoulders and rather thick: one bottle was sufficient. Longer or thicker hair will require two bottles.

If is left on for an hour (I used Colour B4 Extra), after which you must rinse for at least 5 minutes. I did not do this, because my shower head is broken, and life's too short.

Once rinsed, you lather it wit 'buffer', which I suspect is essentially clarifying shampoo, and rinse for a further 5 minutes.

After one application, the dark, almost garnet-like colour of my hair was raised to auburn. It is not a miracle, but as anyone who has read about henna removal knows, this was fairly amazing as a first step. I then used an entire bottle of John Frieda blonding spray to no effect - which should reassure users of Caca Rouge that you can use a lightening spray over it without your head going up in flames!

CB4 can be used more than once, so the following day I did another application. I have been left with a pleasing shade of golden blonde, and am stunned by the difference. There is still more red there than I would like, and so I will spend perhaps 3 weeks washing with John Frieda blonding products before the final step of getting some highlights.

After 2 applications of CB4 Extra my hair isn't noticeably dried out (it is less full than before because henna is, famously, very nourishing and thickening for your hair), and there has been absolutely no breakages. There was a very slight stinging sensation on one area of my scalp where I suspect I might have had a scratch anyway - certainly nothing to trouble me.

To summarise:

Yes, you can remove henna
Yes, you can use B4 to remove henna - just check it contains no metallic salts and do a strand test
Colour B4 is not a one-hour miracle: you will need to do at least 2 applications, and perhaps more, and be prepared for 'warmth' in your hair if you were previously blonde.