A 30 year painter told me to stop sanding primer with 180, and my comeback rate dropped to almost zero
A guy named Ray who ran a paint booth in Fresno for 30 odd years told me this back when I was starting out. He said 180 grit on primer was cutting too deep and leaving scratches that showed up a season later in the sun. I ignored him for a while because 180 is what I had always used, and the scratches looked fine wet. Then I had 3 jobs come back in one spring with fine lines showing through the clear on the hood and roof. I switched to 320 on a DA for final primer prep and blocked by hand where it mattered. That was 5 years ago and I have not had a single sand scratch comeback since. Curious what grit you guys finish primer with on a daily driver panel.