If I'm spraying additional nitro clear over a nitro finish that is already cured, should the full 21 - 30 day curing period still be observed? Or would the curing period be less than that for the new coats?
The wait time period resets each time you spray. You need to wait the whole 3+ weeks. Spraying the new coats softens the old ones. Nitro curing is the solvent evaporating. You need to wait til it doesn't smell much like nitro and the finish becomes dust on your sandpaper, if it's not evaporated it will gum up and be sticky and not polish, and sanding runs the risk of pushing sanding material or dust into the finish.
The wait time period resets each time you spray. You need to wait the whole 3+ weeks. Spraying the new coats softens the old ones. Nitro curing is the solvent evaporating. You need to wait til it doesn't smell much like nitro and the finish becomes dust on your sandpaper, if it's not evaporated it will gum up and be sticky and not polish, and sanding runs the risk of pushing sanding material or dust into the finish.