I have recently turned a pen using oak and yellow wood. In both situations I used the same standard pen turning sandpaper (150 - 600) and found that the grain on the wood kept getting a grayish or brownish dusting into the grain that made the pen look like crap. I have not noticed this problem on darker woods. It almost looked like maybe I was sanding to hard and to high a speed and was almost "burning" the saw dust which was then sanded back into the grain of the wood. I also noticed that the darkest areas was closer to the bushings and thought that maybe I was hitting it with the sandpaper and some of the metal dust was coming onto the wood and getting pushed into the grain. Anyone have this issue and a solution?