There seems to be a lot of people checking out Colour B4 on the net.
It's hard to know if using it will be good or bad though, it all depends on the colour of your hair and how many times it's been dyed.
My experience with it was pretty bad. I suppose though, it did what is said on the tin; it will remove colour build-up but may leave hair ginger. Mine was not just ginger, it was almost flourescent! I'm telling you. it was awful.
I'd say use this product if you've dyed your hair once or twice and it's because it's gone wrong. in other words use it for a colour correction and not to go blonde- as i did. The ginger tones were really hard to cover up! it says use a semi-permanent dark ash blonde to cover up the ginger, which is what i did. i found it didn't work though, my hair was still ginger.
Oh i cried.
I literally used about 3 more ash-blonde hair dyes... to no avail! It was more strawberry blonde though! And they were permanent. i didn't think the semi-permanent ones worked to cover up very well. In the end i went to the hairdressers and got a half a head of highlights and a base colour to match my natural colour. it cost me 90 quid -_-
My hair dresser friend does my hair now, i just have a full head of highlights put in and that's covering up the gingery tones well enough. And my hair is growing so the gingery-ness is about halfway down my hair to the tips. Eventually it will be all gone, but i guess that'll be another year.
My hair was a really dark brown before, and i'd put on many different shades of brown. The hair dye i used was the Casting Creme semi-permanent ones (No ammonia) so i thought buying the extra strength colour B4 would be good for removing the colour build up. I kind of wished i'd had my hair bleached though now. Colour B4 made my hair feel awful and it smells foul. The only reason i didn't bleach it was because i was scared to ruin the condition of my hair.
But seriously, if you can afford it and have a good hair dresser, bleaching may be the better option. you're also more likely to get your hair to the colour you want after bleaching, it's like starting again.
Now my hair's a lovely ash colour (some ginger tones remain) but it has taken me AGESSSS!! to get it that way!!! You shouldn't dye your hair too many times after using colour B4, let your hair have a rest from all the chemicals. I waited a few weeks each time befor putting another dye on, so i was gingery for a while.
If you have the patience and don't mind having gingery hair (i thought i wouldn't until i saw the colour) then i'd recommend using it, i am, after all, now blonde!