These are some of the hardest coins to clean, especially once you've gotten to this point, because it's
plated fourree denarius, and
part of the plating is gone, revealing corroded base metal core.
(I'm assuming it's plated; if I'm wrong, the comments are totally inapplicable!)My comments are amateur experience, so hopefully those with better experience or actual training can correct any bad advice:
When I used to do uncleaned coins (ca. 20 years ago), I
had a lot of these --
fourrees with thick but broken silver foil wrap. The hard
part is they usually have big encrustations (and you can't see what's underneath til you get there).
It looks like someone has already done a
good bit of
work with a scalpel and/or
pick. (Small marks on the
obverse.) If you're
good (I wasn't), that can
work well.
It looks okay-ish now. My inclination would be to do nothing or just tidy up the lighter, easier "rust stains" and leave the darker, deeper, smooth brown encrustations (e.g.,
Roma's helmet/left
side). It'd be nice to smooth out some of the gritty/grainy stuff near the
rev. edges, but it's risky. ("Shaving" w/ a scalpel, combined with weak acid, might be the best bet?) There's probably copper/base metal core underneath, potentially impossible to smooth. You could lose little chips of silver at the edges.
But yes, an acid like lemon juice or vinegar (diluted) for the light stains. I'd start with a cotton swab or small brush and
work up to my familiar solid
tools (toothpicks, pencils) used gently, dipped in the solution and gently scraped/rubbed/brushed in a very focused
area (preferably w/ magnification, but not always necessary). It's time intensive to do one-coin-at-a-time manual cleaning, but if you soak it took long or use too much indiscriminate force, you can lose more of the plating easily.
In my experience, most of the time, once plating is broken and they're crusted over, this is your "best case scenario" (
click, these images expand):
I think this was an "after" photo from one of my uncleaned lots in the 00s... This must've been the best result I ever got. I'd call this 1-in-100 results for a fourree found in an uncleaned lot.
I once found/cleaned a Vespasian Judaea Capta denarius fourree, looked a lot like yours in condition, not pretty but I really wish I'd kept it -- or at least a photo!!Go wild with lemon juice and these are more like what you'll usually get (left coin, Septimius, is after trying out some kind of chemical re-toning, I forget):
