lowest grit to sand clearcoat before shooting 2 more coats

[Bob Hollinshead]

For unreduced clear 320 dry works, 400 wet works. Wetsanding leaves a more aggressive scratch usually just because the paper is staying cleaner while you sand giving it a deeper cut. Remember the old paint cans that read: surface prep 400 dry or 600 wet? If you're doing flow coats with over reduced clear I would lean towards 600 wet just to be safe.

 

[Barry]

Wetsanding leaves a more aggressive scratch usually just because the paper is staying cleaner while you sand giving it a deeper cut. QUOTE]

That makes total sense and now I do remember the old cans.