MIMF

I sprayed my archtop with what I thought was enough nitro finish, let it cure for 3 weeks, level sanded it, and buffed it out with medium Menzerna dry polish. However, looking closely I discovered that I could still see some tiny shiny (shrinkage) spots especially in the re-curve area on the back so I tried to level them out with 600 grit wet sand paper. It didn't seem like I sanded that much but I am starting to sand through and there are still some shiny spots in the location as well as elsewhere. So, I am thinking that the finish just wasn't thick enough to begin with. Would there be a problem with spraying more coats of nitro and repeating the process, even after having buffed it out with medium Menzerna polish? I want the finish to be right. Since the new finish has been buffed do I need to sand it with 320 grit or something to rough it up before applying more nitro finish?

Wipe it down with naptha, make sure it's clean and you can spray more on there.

Finish dried 3 weeks, I would probably spray it lightly with thinner a couple minutes before spraying more lacquer, this helps 'open' the surface to the new lacquer. It's not necessary if you don't sand through again but helps, especially on older lacquer.