Hair colouring for tween

[Serena1977]

I'm not even sure there is such a thing.

Dd is almost 10 and wants to colour her hair pink, blue etc for fun now it's the school hols.

Obviously I won't allow a dye which she knows but is there anything that she can put in that washes out at the next hair wash etc?

Thanks mumsnetters!

What about hair chalk?

Hair chalk, dd 7 has some from Amazon that you comb in and then it just washes out

Sorry why can't you use temporary dye?

If long hair, bleach and dip dye the ends then get them cut off before returning to school with much shorter hair!