it's not a surprise to any car guy that a great paint job is nearly endless prep, and intense scrutiny on the base layers of primer and sanding... but this is a new trick to me to see the scratches that have to be removed before paint (we've all seen WHY! No one misses the deep scratches under the paint and clear)

 so, look at this, a powder puff for a guide coat that shows those damn invisible scratches so you keep at it until the primer is perfect, and the car is ready for the color paint:  https://www.facebook.com/reel/1108005260479364

He's working on a 72 Demon... I get a kick out of that, I had one with a 340 and 727