I use my flux brush to flick off gobs of solder from the bottom of a horizontal joint and to flatten any runs on a vertical joint whilst it's still molten... Can't always avoid a run, even though I do wipe excess solder from a fitting before heating.
It bloody hurts when you flick it into your own face or back of your hand though
It bloody hurts when you flick it into your own face or back of your hand though