Before sending to the sandblaster.
Old damage, revealed after blasting, is finessed with shapers and hammers.
A thin skim coat of body filler is applied and then sanded until it is almost almost gone.
Followed by the first coat of primer.
The first coat of primer is again blocked and sanded to achieve a smooth finish and crisp details.
This primer / sanding process may take place a time or two (or 7) before the finish is as smooth as glass and ready for the color coat.