I found the colour took well and was very vibrant - it did wash out a lot after the 6 washes which I expected, but even when the orange was fairly washed out it still glowed under UV - it glows green!
I used it on bleached hair (just the last 10cm). From experience you do need to wash your hair the day before and use no conditioner or products so it can coat onto the hair - and rinse in cool water and also do not use conditioner or products after. The one time I used conditioner after most of the colour came off when I rinsed the conditioner. It does tell you these things in the instructions, but if you are like me you might not have read every detail!
Unfortunately this dye did not take to my hair. I used it on bleached hair and it did not deposit any colour which baffled me. Waste of $$. Will keep to vivid orange.
Wouldn’t recommend on anything darker than a base 9
Great colour, glows well under uv, easy to apply, doesn't stain fabrics etc much, will buy again.