If the wire coils are supposed to be stainless steel, you can leave them pretty much the way they are, maybe just dull them down, if they appear to be too shiny.
If you intend to model mild steel wire coils, I´d suggest to pain them a dull or broken black, just like Wolfgang stated and to give them a light wash of rust colored brown, as mild steel corrodes pretty quickly.
I would start with a broken black for new coils. Next step I would use felt tip pens. .
Wolfgang
Pueblo & Salt Lake RR
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I just picked up a "coiled wire load" by chooch (no. 7221), any suggestions on how to weather it...pretty new to this. Any suggestions would be greatly appreciated!