I'm in the process of polishing the lips on a set of Borbet Type B rims and there are some spots that don't seem to be disappearing with wetsanding. The coarsest grit I've been able to find at a local auto parts store and HD/Lowes is 220. I also tried a coarse sanding sponge that seems to be 60 or 100 and still am not having any luck. Does anyone recognize what these are and more importantly, how to remove them?
