Whitish Film On Large Cent

IMO it's just another form of oxidation.
Acetone is okay but I suspect it'll have little or no effect.

As for VerdiCare, that is one method of cleaning the coin.
As long as you keep the coin for yourself, then fine, it satisfies your collection.
But it will be detectible for quite a while.

An alternative method is using olive oil which is slightly acidic.
And after a period of time (weeks or months) when it's done its job, THEN give it an acetone bath.
That will remove the olive oil and the coin will be quite presentable.

More specifically mercuric silver wash not silver plating. Seen this many times on contemporary counterfeits but occasionally on legitimate coinage (regal coinage). Sometimes it was done even though it says ONE CENT to pass a particular specimen as a higher denomination is silvered or gilded. The illiteracy theory back then ... ?

John Lorenzo
Numismatist