Once I have my stems all polished, I will put a coat of Renaissance Wax over it, and polish it up to a thin sheen. Then after each smoke, I will hit the stem with a jeweler's cloth after each smoke to keep them all black and shiny. Maybe, I will coat them again with the Renaissance Wax, maybe not. But, it does at least prevent oxidation between uses, if a pipe becomes a bit of a wall flower on the rack.
But, yeh, if you just smoke a pipe and then rack it without doing anything for the stem, you're just asking for oxidation.
But, yeh, if you just smoke a pipe and then rack it without doing anything for the stem, you're just asking for oxidation.