Rainbow hair

In her childhood and early youth Barbie really wanted to paint her gorgeous blonde hair in all colors of the rainbow, and her parents allowed it to heron one condition: if she would paint them only temporary paints and gels. Thus every time Barbie could come to school or to her friends with a new hair color, and keep them alive and beautiful at the same time, without damaging them with a chemical paint. And what paint do you use to dye your hair?