Every now and again I recognize that my brushes need a thorough wash. I try to maintain them regularly with Masters Brush Wash or non-toxic dish soap and warm water, but then once in awhile I decide to soak them in a mixture of 1/2 warm water + 1/2 Murphy's Oil Soap. I do the same thing with my brayers. It's especially important on the brush I use with gel media as that can harden up very quickly. I'm pretty tough on that brush.