Ebony Briwax is beautiful on wrought iron. Yes, Briwax can be used on metals. If there is any rust on the metal piece, the rust will be sealed with Briwax to prevent any further oxidation.
When applying Briwax, if the wrought iron is rough, use sand paper with a LIGHT hand to smooth the surface.
Then buff to a beautiful sheen. That’s all there is to it. Remember to use Briwax sparingly — it is better to make 2 light applications than one heavy application. Always buff between applications of wax.