Don't know if we're talking about the same thing happening, but when I do light resurfaces of stuff that has pits/scratches/etc. in the cover due to use, if I'm using a polish that acts like a wax, I'll get white dots where the pits and scratches are, and that's the wax material getting lodged in the holes.
Some dark coverstocks, however, have white streaks in them -- is that what you're referring to?
Jess
