Lacquering on copper, usually done with Incralac preserve the
object from corrosion very effectively as long as it is done perfectly,
any area that is no covered with the lacquer will corrode much
faster than if the object was not coated at all it is called 'preferential
corrosion'.  From my experience I also would advise to renew the
coating at least every 5 to 7 years as it does crosslink in time and
become quite difficult to remove.
Renaissance wax has the same quality and draw back than
Incralac i.e. preferential corrosion, but it is easier to apply so there
are less risk of missing a bit. It has to be redone every 3 years but
again, it is easier to remove.
Have you considered using less abrasive cleaning methods?
Dominique Rogers BSc (Hons) Conservation-Restoration,
Ipswich.U.K.

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