Do you use Renaissance wax? It's a beautifully fine pH-neutral wax that can be used on wood, metal, leather and more. I use it on all my copper pieces - my bowls, ornaments and decorations - to protect them from oxidisation and it gives a lovely soft sheen too. It was developed for the Britsh Museum for help preserve their artifacts so it's good stuff! Currently a pot of the wax is about £15 and a little goes a long way. I've had this pot for about 5 years and it should last me a few years more!