"how it came from the factory" with early Fords was a lacquer applied by brush. It was some sort of nitro chemical, perhaps a bit like nitrocellulose (gunpowder). Paint chemistry and application has changed a lot. New cars mostly have bodies dipped in primer and sprayed with $100K rotary sprayers using electrostatic charge to move the fine mist to the car body and reproducible robot-arm controls. It comes out so smooth they don't even buff, other than in small spots, which a computer imaging system flags for the workers.