Typically with metal spraying, it is usually a zinc metal spray straight onto the surface. On top of that is a coating of epoxy or urethane coating and that is a very expensive coating, but has been proven to get good coating life. The other is a three coat system where you are putting on a zinc rich primer, an epoxy build coat and then a urethane top coat. The reason you have the urethane top coat is to maintain good gloss and cleanliness so you don’t get contaminants sticking to the surface and the chalking that typically comes with epoxy coatings.
Normally in the coating, just without the metal spray, typical DFT is a total of 350-500 microns which is 14-20 mils. With the metal spray, because it is a very rough finish, the coating on top of metal spray is normally 16 mils.