If, however, your pickle is in use, but not overused, and you
accidentally introduce iron into it resulting in unwanted copper
plating, removal of the piece of iron will immediately stop the
process, and you may continue to use the pickle with no further
plating of objects. Steel wool is an exception in that the little
fibers of it are too small to completely remove, so you might be
unable to stop the reaction.
Les, even things like steel wool won’t cause a problem. Remember
that the iron, in order to set up that galvanic circuit, has to be in
physical/electrical contact with the item that would then be copper
plated. Small fibers of steel wool will sink to the bottom, where
they won’t be in contact with anything, and thus won’t complete a
circuit. And even then, they’ll quickly enough dissolve in the
pickle, and again, as you’ve pointed out, no longer be able to cause
a problem. Enough iron dissolved in your pickle, though, can change
the appearance of subsequent accidental copper plating through
additional introduction of one’s soldering tweezers. if there’s
enough iron in solution, AND if you introduce something more reactive
than iron itself, such as zinc plated tweezers (yikes), then some of
th iron will plate out in addition to copper. Makes it look even
worse than with the copper. But as you can imagine, one has to be
REALLY careless before this situation gets set up… (grin)
Peter