I just used a product I don't think I will ever be "without" from now on.
Windsor and Newton Brush Cleaner and Restorer. It seems as if a brush or two that I lay down I never pick up again and/or a dirty brush rolls under my painting lazy susan that I use. DRIED PAINT....and a lot of work to get it back to normal.
This "stuff" is unbelievable....it still takes a little time but it has really brought a couple of my bad brushes back to useable, so I am delighted.
It is not-toxic, water soluble, non flammable, non-abrasive and low vapor and comes in several sizes. I just purchased the 4 oz size and I found it at JoAnnes which was a real shocker as they carry so little in artists' supplies.
So give this product a try....you will love it.