I dug out my packet of Router base bushes which I’d bought a few years ago and never used.
They’d been kept in a drawer in my router table together with some other tools.
On opening they were all rusted to a varying degree with the nickel?? coating removed in patches.
None of the other tools were rusty so I can only assume the cardboard container was damp or had attracted moisture??
A quick soak in Phosphoric acid got rid of the rust and most of the remaining very thin coating!
Now sprayed with a thin oil and stored away.
Rod