Could l just add a little to the above having had a Powder Coating plant as part of my Wrought Iron business (now retired). There are 2 types of powder, Epoxy, cheaper and more suited for indoor use and Polyester, dearer but more suited to outdoor use. We used to re-powder wheels for friends only as it was a pain in the bum. Epoxy powder if left un- lacquered outdoors, will loose it's shine within a couple of days, where Polyester won't. Obviously the best finish is Polyester lacquered, but to save money we have seen others use Epoxy.