I am appealing to the collective wisdom on the forum regarding cleaning a shave brush using an ultrasonic cleaner. I normally just dip the bristles in the ultrasonic with great results. However I have a few brushes that have a metal ring just above the knot. The ring gets lime deposits and soap scum on it and I was thinking of using the ultrasonic to clean the ring. My worry is that the vibration from the Ultrasonic may loosen the knot. What would be the best (i.e. safest) way to clean the metal ring and handle of a shaving brush?