I did the wiki/em's method (dish soap, then vinegar + gently scrubbing with a toothbrush). It's still got a white ring of scum around the base of the knot. I'm a minimalist and don't have a collection of brushes. This is it. So what's next? Any "shave brush cleaners" like Classic Brand or Gold Dachs work better? (It's a Merkur Futur Silvertip, FWIW.)