Definitely a job for a jeweler's cloth.My one Peterson (spigot, acrylic stem) sits in a pipe rack on the mantle, not in the sun but in open air in an air-conditioned house, and it has been several months since it was polished. It's not super bad and black or anything, but it's distinctly brassy looking and has had this brassy look since maybe 2 weeks after the only time I ever polished it.
Even then, I only polished it because there was a black finger-print mark on it.
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