Rust question with pic :
I have stripped roof best as possible (vinyl top car, so has "issues") , I have removed the majority of rust using various methods and Naval Jelly, etc. I am going to be blasting the pitted, black areas (red circle and similar) - my question is the grey "freckles" which seem to be discolored due to previous rust (no pits, no texture). I've been over these areas with sandpaper and stripping wheel. My assumption is these are stained areas and I'm good to prime and move on (?) I'd like to see perfect, as new metal but would need to go deep with 60 grit or so and will if necessary.