Auto body repair & detailing: primer, spray paint, wet sand

Question
what sandpaper should I use on primer prior to painting?

Answer
Hello! If you are giong to hand sand the primer, spray a mist coat of black spray paint on it, then wet sand it with 600 grit wet or dry paper. When the black spray paint is gone, you have thourally sanded the primer. You can also machine sand it with 400 grit dry. You can use the mist coat trick on that option, also, it does a great job. hope this helps! Bill