Primer is under the paint.
When oil rigs are constructed, they are coated with rust inhibitors before they are painted. The structure is constantly monitored for rust and is re-coated where necessary.
Most of them are not painted they are wrapped!
90% of the cars are painted white.
by a machine
No.
some painted one once
cars are smooth because they are sanded down and then spray painted with nylon paint
No.
Cars are painted during the manufacturing process, but before final assembly. Once the metal frame of the car has been built, it is sent to a paint shop in the factory. The frame is then painted one of the colors offered for that model. What color the frame is painted, as well as how many will be painted in this color, are determined by the manufacturer. Doors, hoods, trunk lids, and other pieces not part of the frame are painted separately. These pieces are all put together in final assembly, as well as adding the interior.
SO they don't rust.
Some were painted with a brush, some were dip painted, and some were spray painted.
Finland exports cars, steel, wood, and kaolin coated paper.