I haven't. However, they look quite exciting. Apparently you can use them to add a bit of colour, in stripes or other configurations, which washes out in two shampoos. Even though I am 42, and a chartered accountant, I am strangely drawn to the idea of purple stripes/ombré for the weekend.
Has anybody used them? I presume that they are liquid colours you paint on and leave to develop for a bit, rather than, you know, actual chalk type things? I must know.
Anticipating advice from the hair experts!