I tried searching and found some hits but nothing that really said it was bad other than it might turn the media black so I tried a bit and compared it to some previously tumbled brass which I only used corn cob media and a bit of car wax. The results were great if you want really shinny brass! This was the best picture I could take to show the difference. I came up with this idea when I made a couple of bullet necklaces and polished them with my dremel tool.