Restoring Cumberland Stems

I have recently acquired a couple of estate pipes that have cumberland stems. (And I mean real cumberland) When I restore a pipe I generally initially rub the outside with cotton or a rag soaked in alcohol. This is to sanitize the stem if that is all it needs and to remove any lose buildup if there is a heavy restoration ahead. When I do this on the cumberland stems I get a reddish / orangeish transfer to the cotton or rag. The finish is also much more muted. Is this oxidation that is just camouflaged due to the similar color of the oxidation on the cumberland or am I dissolving some of the stem? I am assuming the muted color is just the removal of the wax/polish but I just want to make sure I am not hurting the stem. These pipes are the nicest pipes I have and do not want to take the chance of ruining them. I also want to know if it is oxidation, do I need to keep going cleaning them stem.
Any help is much appreciated.

Thanks for the info guys.
So based on what you guys have told me I am coming to the conclusion that the transfer I am seeing is the oxidation I am removing and need to keep going. I much prefer the look and feel of the cumberland stems. I usually still use a pipe bit, but even with that I can feel a big difference compared to Lucite. I have sensitive teeth and sometimes I just have to stop smoking a pipe with a Lucite stem do to the irritation I feel.