I ordered this product because our niece wanted it for her birthday. She's a teenager, so I thought why not? This is a horrible product. When she would try to color parts of her hair with the chalk, it would break into small pieces and you have to keep rubbing it on the hair several times for it to show up. Once it was on, when she moved her head, her shirt had small dusty blue particles on it. This was a messy product and one that doesn't work well.

I use many different hair colouring products, usually love them all, but not this one.. To get colour, I have to push really hard, and my hairs get torn and pulled out, and then there's not even much colour. I have gotten vibrant colour from this using hairspray and applying both multiple times. But without hairspray, there's not much colour, nor does it last very long.
In my photos, I did one strand on each side, the right one (vibrant blue) was done by applying the hair chalk and hairspray multiple times, back and forth. Chalk, hairspray, chalk, hairspray, etc. The left side (grey-ish tone) was done with just the hair chalk, multiple applications. You can really see the difference.