I have been using two rubber bands of approximately an inch and a half diameter almost at the base of my floppy badger brush knot. It helps noticably and although the brush is still floppy, it doesn't wander around as much. It doesn't seem to hold water or lather any differently and it hasn't made a difference for me whipping up cream, but it has helped somewhat with getting lather out of soap.

I have assembled a 7-day set of these rubber bands (14 bands in all) and am interested in seeing if this improves the shelf life of the rubber bands after being exposed to lather components every morning (save the occasional Sunday.) I also experimented with several different colors of rubber bands, and tried to press jimps into one of them for easier removal from the brush, but they just kept bouncing out until I pressed so hard that it snapped in two. Maybe I should try sanding them in?

Anyway, your simple idea has improved my morning shaves ever so slightly - thanks!