I've always been inclined to use small wads, because to conserve wadding, because mixing it up is sort of tedious. I see now that I have been cheating myself! When the wads are too tiny, the flame, with its load of soda vapor, can't get under the pot; so the bottoms are pale and pasty and dull. Okay, that's harsh; but using bigger wads does allow vapor glaze to be deposited on the bottom, resulting in this soft, peachy, flame pattern. It's the subtle things that make a piece sing, and a beautiful bottom is definitely a plus.