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Author Topic: Help to Clean Silver Denarius  (Read 481 times)

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Offline Rafael Augusto De Mattos F

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Help to Clean Silver Denarius
« on: February 16, 2023, 10:40:47 am »
Hello guys, need your help, any tips for cleaning this coin? As a high silver content can I maybe use citric acid (lemon juice)? Or ammonia? Thanks in advance!


Offline Jay GT4

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Re: Help to Clean Silver Denarius
« Reply #1 on: February 16, 2023, 01:51:06 pm »
Looks like a plated fouree

Offline Curtis JJ

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Re: Help to Clean Silver Denarius
« Reply #2 on: February 16, 2023, 02:21:20 pm »
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):

Offline Rafael Augusto De Mattos F

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Re: Help to Clean Silver Denarius
« Reply #3 on: February 17, 2023, 10:40:01 am »
Thanks guys. Yes its a fouree coin, unfortunately... I soaked it on lemon juice for a few minutes and used a soft toothbrush to clean the thick parts... I will fisnish as it is, not much for improving and Im not expert on it...




Offline SC

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Re: Help to Clean Silver Denarius
« Reply #4 on: February 18, 2023, 10:56:34 am »
To me that's a pretty respectable result for a Republican fouree.

All details legible, nothing too ugly remaining.

I love fourees by the way - such a neat phenomenon that gets into the "darker side" of the ancient economy.

Shawn

SC
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Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #5 on: February 18, 2023, 11:19:33 am »
The best (if not the only) way of cleaning corrosion and dirt from a plated surface is doing it mechanically i.e. with a scalpel under a microscope. Currently I am cleaning a lot of fifth/sixth-cventury Merovingian objects which come out really well. It takes ages, but it gives the best results.

Offline Tracy Aiello

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Re: Help to Clean Silver Denarius
« Reply #6 on: February 18, 2023, 11:24:47 am »
Frans,

Wow, that result truly is amazing. I can't imagine how much time and patience that kind of cleaning must take, but in the end it looks worth it.

Tracy

Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #7 on: February 18, 2023, 11:31:46 am »
This object took me about ten hours to clean.

F

Offline SC

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Re: Help to Clean Silver Denarius
« Reply #8 on: February 18, 2023, 12:48:28 pm »
Fantastic item and fantastic cleaning job Frans.

I would love to see the other Merovingian objects.

SC
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Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #9 on: February 18, 2023, 06:56:44 pm »
I can show you the pictures of the uncleaned objects and will proceed (after the work is done) with the clean versions. It is an extremely interesting lot altogether. Some have (unfortunately) been soaked in olive oil which leaves a mess, and others come straight from the French soil.

Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #10 on: February 18, 2023, 06:58:01 pm »
lot 2

Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #11 on: February 18, 2023, 06:58:45 pm »
lot 3

Offline Frans Diederik

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Re: Help to Clean Silver Denarius
« Reply #12 on: February 18, 2023, 07:00:05 pm »
lot 4
When I show the cleaned items, I will do so in my own thread, as I am stealing right now.

F

 

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