These are some Photos of painting Interior Steel Doors
Photo #1 First we use var sol or paint thinner to remove the oil that is usually on the doors from the factory. there are stickers that have to be removed as well and possibly use paint thinner to remove the glue. Then we have to prime the doors ( primer sticks to the metal ) then the paint will adhere to the primer coat.
Photo #2 I think this was 1 finish coat on the doors and wall on top of the primer coat.
Photo #3 The final finish is on the walls and the doors and door frame.