Sometimes I've gotten little tarnish spots on brass I haven't loaded in awhile. However, once I started putting tiny amounts of NuFinish in my tumbler media, I haven't seen any at all. I think maybe it leaves enough on the brass to prevent the spots.
Honestly though, the spots were rare enough that it's hard to say whether it was the NuFinish or just maybe that the humidity in my garage had varied slightly for some reason.
Mike
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