Since last time, I roughed-up the surface of the fretboard and applied another thick layer of poly. Normally, I let poly dry for a week at least before I touch it, but I got restless. After two days drying in a warm place, I smoothed it down with 400 grit and then polished it up from 1000 to 2000, all dry as I do not want to get water in the fret slots. Finally, I decided to try the polishing wheel on it, and the result came out very nice - like wood underwater.