Ok so I tried it on the gold rods. No sanding, just cleaned with some acetone. Result? Well... it's darker, but still golden. The oil has a tendency to bead on the surface as well, so I'm thinking there must be a coating already on the aluminum. I think it could reach a reasonably dark hue with a couple more applications, but for all that time and effort it might just be easier to find a place to powdercoat.