At the beginning of the year I bought tons of "stain" removers. Kiss-off,
special solutions to wash brushes with etc. None of them worked to take out
the stains in class. I tell my students, as hard as it it...don't wash it
out!!! If you let tempera dry (or clay or glaze) then it will just brush
off. The worst is when I seen them at the sink soaking their clothes and
rubbing a big stain in them! It makes them have went sloppy clothes and then
they do stain!