I just recently noticed the weathering of truck axles as I sat
watching a UP freight go through our local grade-crossing.
I've seen many articles, etc., about painting/weathering truck-wheels,
which I've always tried to do myself, but don't recall any about
Next time you sit and watch a freight train go by, notice the wheel
axles. They have multiple stripes around them from whatever reasons.
The trains back in the "old days" of the STMFC period would have shown
the same weathering effects.