An excellent trick I learned at an art store and teaching center in Florida.
Line your clean, empty thinner bucket with a plastic 1 gallon freezer bag. I’ve had the best results using the one gallon freezer bags. I put the thinner screen into the bottom of the freezer bag and then slide the freezer bag into the bucket or 2 pound coffee can. I then use the thinner bucket as I normally would for cleaning brushes and when done, remove the thinner screen, wipe it off with a paper towel and pour the contents of the freezer bucket into my storage container for odorless thinner (or OMS, or baby oil).
It’s beautiful. No more mud build-up.
Thanks Pat Mabe for this really cool tip.