I just tried it last week because I wanted to see how a red shade would look on me, it says it lasts 8-10 shampoos and it looked really great I think.
I have dark blond hair and went for the copper blast, it gave me a darkish red. My hair has natural tones so I think it looked pretty good, I'll try to get a photo up here since I took a few. Also I'm watching how it'll fade, it looks a bit lighter now, I think the dark blond is showing a bit. It's been 4 days I think.
I also purchased the ginger rush, I'm going to try that next once this one comes out, it's also a redish tone, just want to see if there is a difference.
I think it's really fun, no ammonia and it goes on so nicely, it's in a little bottle and if you have hair like mine, thin and just a bit below the shoulder it should cover it all with one bottle, the thick mousse covers well and is so easy to do. My boyfriend actually put it in for me (he did such a great job

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He also read up a bit on the product before we did it and he said if I lathered it nicely with warm water before rinsing it out it made the colour "stick" and we did that for a bit and it turned out really pretty.