90% sure its old powder coat. would be repainting over it. rough up the surface. Ive used rustolem hammer on my sliders and its held up well but does have ware locations but that is given. Im also thinking about getting it sandblasted and powder coated.
Not matching anything and was thinking spray would be easier then rolling it on but im open to either way. I have used 2 part epoxy paint for a garage floor. Not sure how well it would stick to another finish.
edit. Planning on going with a darker color, most likely black.