Acrylic paints are water based and very popular. Although they are easy to use and low odour cleaning the paint brushes successfully after use can prove difficult although this is a very straight forward process.
This is the messy bit, you really need to get your fingers in to the bristles while you are washing it. The warm water will soften the paint and the paint will wash out.
Now the trick, once you think it is clean, spin the brush by holding the brush handle between your hands and the centrifugal motion will take out the paint low down in the bristles. Do this in a decorating bucket or you may get wet!
At this point many people think the brush is clean but if you stop there your brush will still go hard.
Now repeat the whole process at least twice more in clean water, spinning the brush between cleans and hey presto you should have a clean re-useable brush.
Clean up paint spills with warm water and clean cloth.
Job done, Simple!