One year I decided to just buy each student a cheap set of their own
brushes but the quality was so low that the brushes kept falling apart. I
went back to buying decent brushes because most student grade ones are so
bad, I can't even paint with them and I'm an experienced artist. Acrylics
are the worst and many times I just decide acrylics aren't worth it. Not
only do they wreck the brushes, they dry too fast and you can't save them
from class to class once they're out on a palette. Some years I've just
decided to stick with high quality tempera or watercolor. I can teach the
basics of color mixing and painting technique with water base paints.
I think if you create a color code system for all supplies (including
brushes), you can keep track of who didn't clean their brushes. In this
system you color code supplies by table and seat. There are many good
brush cleaners on the market which will remove acrylic paints but not if
its been on there for too long.
I've found that by spending a lesson on brush care, students learn how to
wash and care for the brush--younger kids are much better at this than
teens. Save a few old crummy ones and show them during your class. Ask
who would pick the splayed and hard brush if they had a choice.