If there are any areas the have a fairly large amount of glazing putty still showing on the surface after sanding, I shoot a bit more primer on them to block the putty from migrating into the top color coats. At this point I sand with 400 dry and take the primer back a bit more. I have now removed as much primer as I safely can without cutting through it. I could probably go a bit more, but the 2 or 3 grams isn't worth it. One last quick pass with 600 and I'm ready for paint.

Ready for paint. The surface is more transparent than seen in the picture. Grain is visible over most all of the surface. You could read newsprint under it.