My dad and I built a Tele back when I was in high school and I've never been happy with the way I had originally finished it. If I remember correctly, I think that I was just so excited that it was constructed that I slapped on a few coats of whatever and called it good. The years went by and because I thought the guitar sounded so nice I kept putting off refinishing it because I knew I'd have to sacrifice a lot of time where the guitar was unable to be played. So now, 13 years later I've decided to refinish it the way I had always 'intended' to. Here's where I'm at: I've sanded the body down to bare wood, but the deep crevices of the grain still hold whatever it was that I used as a grain filler. I can't remember for the life of me what I used, but I know I used some kind of filler because when comparing the sanded surface wood to the untouched wood in the cavities it is obvious that I used something. The grain on the surface wood is very dark unlike the grain in the cavities, while the non-grain portions of the surface and cavities match (indicating I'm down to the bare wood except for the crevaces). My question for you all is this: If I am once again planning to use a dark (dark brown or black) grain filler this time around, must I keep sanding away until ALL of the previous filler is removed? Besides the effort involved, I would rather not remove that much material. However, if applying grain filler on top of the old grain filler might pose a problem, I'll do it. In case this detail matters, I will ultimately be applying a clear nitro finish (no tints, colors, etc.) Thanks very much!