Even back in the day, they used Fullerplast on all the ash bodies. That stuff is essentially a polyurethane lacquer. Then they'd put nitro on top.Zombie thread or not, it’s actually still a relevant topic. I started a thread sort of about this last week and lots of people messaged me with questions about fender nitro finishes.
Not so much nitro vs poly but more about what fender models actually don’t use the poly sealer. There’s very little in the production models that use just nitro sealer and nitro top coat.
Using a polyurethane sealer with nitrocellulouse on top is not exactly a new technique.