Varnished items from older collections.

[Norman McCormick]

Hi,
I think some of us if not most of us have come across items from older collections that have had the metal parts of an object varnished in order to protect the piece from rust. I would value the opinions of the members with regard to removal or not of this type of old protective varnish. If removal was proposed then how would you proceed and with what method? I look forward to your opinions and suggestions.
Regards,
Norman.