FORVM`s Classical Numismatics Discussion Board
Numismatic and History Discussion Forums => Uncleaned Ancient Coin Discussion Forum => Topic started by: Joe Sermarini on January 20, 2005, 11:38:09 pm
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Discuss methods for cleaning silvered coins (that is silver plated or coated coins) here. If you have questions about a specific coin, please start a new topic.
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Ave!
OK, it's about time I chimed in to this thread.
Silvered issues comes in all sorts of condition...from already shiny to dark black to encrusted, etc.
In the case of the coin seen below, it appears to be a hopeless mess, eh? Not so.
As seen in the first photo, we can see just a bit of silvering beneath the encrustations. That is a good sign. Looking deeper, we see that the basic portrait and legends appear to be firm and intact. Even better. Now, use a dental pick to gently probe the surfaces, a scrape here and there to to be sure that the silvering is firm, rather than flakey or brittle. In this case, the silvering was firm and intact.
After I established the above condition, I was ready to clean the coin. Short soaks in lemon juice (2-3 minutes) helped to soften the green encrustations. After each short soak I applied a Diamond-dusted Dental Pick #1, my favorite tool, to gently remove the softened encrustations, then a very quick and gentle brush with a soft-bristle Dremel brass brush under running water. Half-way done as seen below.
I continued to repeat the above process, but now using a Diamond-dusted Dental Pick #2 to clean between the legends and for the final detail work. A last brush with the soft-bristle brass brush and the final result is as seen below.
I was very lucky with this one. The entire process took less than two hours.
As time allows, I'll further thoughts/methods to this thread.
Your opinions?
K
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Ave!
a very quick and gentle brush with a soft-bristle Dremel brass brush under running water.
Doesn't the dremel brush leave scratches on the silver surface?
Joe W.
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Ave!
Ave!
a very quick and gentle brush with a soft-bristle Dremel brass brush under running water.
Doesn't the dremel brush leave scratches on the silver surface?
Joe W.
Not, not really... This brush has very soft bristles. As long as you remember too barely touch the coin's surface, you should be okay.
K
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Hi All, thought I might chime in on this thread with some experience I've had cleaning a silvered radiate antoninianus received in a recent uncleaned batch. Not that I had any inkling it was silvered as it had moderate to heavy blue green corrosion present all over with no sign of silver. Initially when the silvered parts appeared I had thought it was fragmentary as there were large patches of brown... however, I've found these brown patches (which underlay the green) also lie on top of the silver and that the silvering appears at least 90% intact. Since the silvering was detected I've progressed by dabbing the corrosion and brown patches with lemon juice on a cotton bud and scraping with a toothpick or gental picking with dental pick. Anyway, just an observation to add that green on a silvered coin, even total coverage, doesn't necessatilly mean the silver is lost. I'll post a pic when done.
cheers,
Rob
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Here is an interesting coin that I picked up a couple of years ago with ten or twelve others in a lot -- all ants, most with some silvering, all very harshly cleaned with chemicals so that basically no patina remained on any of them. I didn't mind much at the time, because I was more interested in learning the type, and the details on the coins were clear. So I tossed them into a drawer for the past two years and voila! they are toning nicely, as is the example below.
Notice that there is a definite silver layer above the bronze core. See obv from 1 to 7 o'clock, the bronze is exposed on the right half while on the left half of the obv the silver layer is plainly still in place. Likewise, the silver layer -- it is not as thin as I'd expect "silvering" to be. It is more like a clad coin -- bronze core, silver laid on top. Sort of a nice contrast, all in one coin.
Probus, AD 281, Rome, AE Antoninianus, 3.46g.
Obv: Bust type F (radiate and cuirassed bust right); PROBV - S PF AVG.
Rev: Victory advancing left, holding wreath and trophy; VICTO - RIA AVG.
Mintmark: R thunderbolt Sigma (sixth emission, Rome mint).
Enjoy,
Mark
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Here is a before and after shot of a coin I have just spent an hour cleaning. Those of you that recognise this as a very rare (R3) piece (and a very attractive one, I feel), will understand that I ummed and erred and dithered for quite a while before deciding to go ahead and clean it. Add to this the fact that it is an ex-Spink coin, and most would cry "STOP!! WHAT IN GOD'S NAME ARE YOU ABOUT TO DO?"
But I think the results speak for themselves. Don't you?
For those that are interested:
Constantine I silvered AE Follis. Trier, 318 - 319 AD. IMP CONSTANTINVS AVG, bust of Constantine wearing high crested helmet, cuirassed with spear over right shoulder / VICTORIAE LAETAE PRINC PERP, two Victories standing, facing one another, together holding shield inscribed VOT PR on altar. PTR in ex. RIC 208a
Very Rare - R3
Ex Spink VII 1996
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I find that the simplest technique is often the best. I just immersed the coin in lemon juice for 2 minutes at a time, removed and scrubbed with a small nylon bristed brush, and repeated the lemon juice/scrubbing until I was satisfied most of the gunk was gone.
Of course, you're then left with a very bright silver coin. Normally, I hate the idea of tampering with silver toning but in this case since I had removed it, I felt I could retone it without any ill conscience. A very weak solution of sulphurated potash (liver of sulphur) will, over the course of about twenty minutes, restore a somewhat darker appearance to silver.
Ta da! And there you have it.
Two caveats:
1) This worked so well because the silver plating was in good condition and not flaking off. Sometimes, it may be loosened by corrosion of the bronze beneath, in which case you might screw the coin up. But hey, nothing ventured, nothing gained. Or.. 'he who dares wins, Rodney.'
2) I do not advocate the artificial toning of silver coins. Natural toning is far far more attractive and desirable.
Hoped that helped in some small measure.
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Kevin,
Thanks for your input and kind words of praise! I must admit, those remaining areas of green encrustation did look glaringly obvious once you pointed them out, and I was 'forced' to go back for a second round. Am now running out of lemons...
Since I don't normally clean coins, I (alas) do not own any diamond dusted implements, nor could I justify the purchase of a dremel. But I think that improvisation is more fun anyway! :) A scalpel, a toothpick and a cottonbud were my weapons of choice this time.
Well, here are the latest results. Still a few spots remaining, but I'm happy to leave the coin as it is now. The helmet certainly looks better.
All the best,
Richard
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I just bought this silvered gallienus. i would say that it is like 60 to 65% silvered...very thin silver.. On the high points you can see all bronze..but there is still some tarnished silver...Any advice on what to do with this coin?
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Leave it, it's great as it is! If you mess with it, you could well end up losing the silvering, and for what?
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I agree. There's no way to improve this coin.
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"Half-way decent" is a different definition for different eras. For a Gallienus I would call this coin way, way, way decent ;)
Definitely a leave as is.
Shawn
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Here is another silvered coins that I am having problems in figuring out a way to clean
the coin itself is
Constantine II
AE 17-19 mm 2.0 grams
OBV :: CONSTANTINVS IVN NOB C. Laureate and cuirassed bust right
REV :: VOT V MVLT X CAESS dot TS dot B dot within wreath
Thessalonica RIC VII Thessalonica 45
RIC rated R1
anyone have suggestions on the cleaning of this. Machanical ( pin vise ) is in progress, but taking silvering off
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Ave!
Johnny,
It's quite difficult but it can be done. Cleaning slivered coins in this condition takes lots of patience and a steady hand.
Try this: soak the coin in distilled water or Gringgott's Conservator's Mix (GG's works best in these cases) for a day or so. Then very gently use your vise pin (copper not steel) to very, very carefully begin cleaning the softened dirt from the open fields. Remember to keep the coin damp. A dab of saliva works best, trust me. When you see silvering, stop, and move on to another area. Repeat, them put the coin back in the soak.
Repeat as noted above: remember, no matter how you try, some silvering will be removed. Patience is a virtue...slow but steady wins the race, eh?
Once you feel that you've progressed as far as you think possible, you're nearly one half finished. ;) Put the coin back in the soak!
Now, using a very soft bristle toothbrush and dish soap, apply the brush, again very gently, to the coin's surface in a swirling motion. Rinse and repeat. Look at the coin. Has any futher dirt been removed? Has any silvering been removed. If the latter, the coins done. If not repeat until your satisfied.
Best I can do.
Kevin
PS - Perhaps our moderator could copy this to the "How to Clean Silvered Coins" post?
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sometimes as you scrub and pick away, tiny tiny specks of silver start to appear. Should I then try to scrape off the darker patina, hoping to reveal a smooth shiny silvered surface?
Raymond
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Here's one with an green algae-like film over it. Scrubbing away, I'm revealing silver. Weighing in at 2.4 g, 17mm, I'm asuming it's silvered and not silver. Should I limit myself to removing the last of the dirt, or keep going and attempt to reveal a fully silvered coin?
Raymond
PS. got to get a copy stand and start taking better pics!
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Just do the dirt, if you accidentally go through the super thin wash silver, you will see copper and that will be bad...I have ruined a few coins now trying to get to the silver... ::)
Chris
PS Yes! The copy stand has been a godsend! You will really dig it when you get one!
Chris
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Hi. Silvered coins, are to me, the hardest to clean. Kevin gives very helpful advice a few posts back.I'm going to try it with a similar coin. One thing I do, and I know it isn't perfect reasoning, is look at the ruler/mint and ask "How many of these have I seen fully silvered? For some, like lets say Costantine II (not your coin), I almost never see a thick enough layer of silvering to ever hope of bringing it out after the dirt is mostly off - I leave those alone. I call them the "thin washies." Other earlier emperors, like Aurelian, Probus, and some issues of Licinius I and II and Constantine I, have rather impressive thick layers of silvering, so I go after those with a bit more gusto. Joe
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i have been cleaning bronzes for awhile now, is it possible just to use distilled water and lots of elbow grease with a nylon brush to clean up a silvered coin
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Here's an example of what I have difficulty with:
On this coin offered by Forum, are the grey areas over the silver, or does it represent where the silver is worn away?
I think I may be too gentle with coins of this kind because rubbing away at the grey area does not seem to reveal more silver and attacking the silver does not appear to wear it away...
More elbow grease? No matter what angle I use to look at coins of this nature, I just can't tell.
Comments?
Raymond
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Honestly, by the pics alone, it looks like the silvering is worn away. Very hard to tell however
I do see spots where the silver is obviously gone.....can you circle the areas in question, this might help
EDITED......nice coin BTW
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Raymond,
I have been cleaning several of these recently.
It looks like you have both types of grey on your coin.
There are some areas which appear dark grey in your photo which are likely where the silvering has worn off (on the obverse - Constantine's cheek, part of his neck, likely the highlights on his ear, dots on collar of his cuirass and highlights of some letters; on reverse - highlights of some letters, especially on the vexilatio/banner, head of captive to left, body of captive to right, thighs of both captives). These areas are problematic. This dark grey patina will start to wear through to copper colour if you brush or scrape too much. Some soaks can make it discolor as well.
The lighter grey is very different, it should appear thick and crusty under magnification. It is around all the details (ie letters, helmet and cuirass details, captives, exergue marks, etc.). This is a form of encrustation which lies over top of the silvering and it is very likely that the silvering is absolutely fine under this stuff. Therefore you can attempt to remove it.
Unlike Kevin I work these coins dry. First I try the toothpick or bamboo skewer on the light grey stuff. It rarely works at this stage but it does sometimes remove bits of the encrsutation. It also lets you test the silvering. Usually silvered coins circa AD 317-330 had a nice thick silvering so, depending on soil conditions, it is usually quite stable.
After this initial probing I take my tools - 1) a steel sewing needle in a pin-vise, and 2) an exacto-knife with curved-tip blade. These need to be very, very sharp! (I keep a sharpening stone handy and sharpen both tools every few minutes.) Then, working with either a magnifying visor or a binocular microscope I gently probe away at the light grey encrustations. You obviously need gentle touch and the right angle (very shallow, almost parallel to the surface).
When the grey is crusty (like it appears to be in many places in your photo) I find it will flake away quite easily. The pin/needle works all around the letters and other details, the exact-knife or scalpel works in the fields and can be used to scrape the top part of the encrustation off detailed areas.
The pin/needle is my favourite tool. If you do it properly it does not leave minute scratches through the encrustation, instead it usually pops the grey stuff off in small chunks. You have to probe gently from all angles. The exacto-kife/scalpel can cause the grey to flake away when used on the top layers. It also cleans the fields nicely.
I usually go around the entire coin, from a variety of angles, once and then put it to the side again. The temptation to keep at it should be avoided at all costs. I have only ever screwed this up when I kept at it in a cleaning session long after the first pass (small scartches through the silvering between letters). I have never scratched or messed up when being patient.
After going around with the steel tools once I usually go over the entire coin with toothpicks/bamboo. This rarely removes more stuff but helps shine it up a bit and shows the results of the cleaning session better.
I must admit that I have never removed 100% of the grey encrustations this way. I only go as far as I feel comfortable with. Sometimes I will go back to a coin which I declared "done" months ago and give it another round. Nevertheless, this route will easily take coins from little or no silvering to 90% or more showing.
There is another kind of grey encrustation which is much harder to deal with. It is dark and smooth and at first glance looks like where the silvering has been worn through. Even though it is relatively flat, when seen under mangification it is clearly on top of the silvering. I think it is the light grey encrustation which has been worn down a bit. It will also pop off and reveal nice silvering underneath but it is much harder to remove than the standard light grey encrustation because it is too smooth to get good purchase on and is quite hard. Usuing the pin gently will occasionally scratch through this form of encrustation. One good scratrch through is often all that is required as you then have a rough edge to catch on to clean the rest. Often though it is the part I just leave.
I am not brave enough to Kevin's methods of long GG soak or sbbb on these yet.
Shawn
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Here is an update on my mechanical cleaning of some silvered 4th century bronzes. These AE3s are circa 316-317 and are from a small hoard I bought earlier this year.
Before photos of a IOVI CONSERVATORI AVGG. I appologise for the crappy before photos. I only had photos of a larger number of coins laid out so this cropped image is small and poor quality.
There is a good layer of medium-hard dry earth, especially on the obverse. Under this is a green encrustation. Under 20x magnification it looked like malachite yet it was clearly over intact silvering. Parts were completely covered by the green, others had only partial covering.
Shawn
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I only took good images of these coins when part way through the cleaning.
First I removed all dirt with toothpicks - either regular round toothpicks or ones I cut with an exacto knife to make a "scraper blade". With patience all the major dirt was removed. However, a thin layer of dirt still covered much of the coin - almost a "staining".
Then I set to work with a couple of exacto blades and a pin in pin-vise (all kept sharp with a whetstone). All work was done under a 20x stereo microscope with a strong lamp to the side.
In these images you can see 2/3 of the obverse and 1/2 of the reverse cleaned in this manner. You can see the different coverings. Dirt over a fairly even green on the obverse. Light dirt over sparse green on most of the reverse with some major green encrustations on Jupiter's head.
Shawn
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The cleaned coin. I probably spent 2-3 hours on this coin.
I have posted two images of the reverse with the lighting angled different ways to try to better show what silvering remains.
Shawn
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Now an early Heraclea campgate from the same hoard.
Poor quality images before the dirt was cleaned off with toothpicks.
Better images before I started exacto cleaning. This coin had more silvering showing and much less of the green encrustations. Nevertheless the encrustations were spread out and the thin dirt layer was all over so the entire coin needed mecahnical work.
Shawn
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Images of the fully cleaned coin. This one took around 2 hours.
All this cleaning was done dry. I have never exposed these coins to water.
Under 20x magnification I did notice that the pin was leaving minute scratches - not really visible with the naked eye. As a result I have tried to minimize the pin use even more and do almost everything with the exacto. With a thin tip blade and the 20x magnification you can even clean between the letters with the blade. I now only use the pin in some hair and beard lines.
Shawn
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I use a #15 scalpel under a stereo microscope. Requires practice, I started by trying on some culls that I had saved to use as give aways. Here are before and after pic of a recent effort.
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Nice work!
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Ave!
The very first thing when it comes silvered coins is to determine whether it's "silver plated" or "silver tinned".
The first example is a Silver Plated fourree; Note how the obverse has buckled up. Too easy to see.
The next example features a pair of Vine Leaf vessel adornments. Looks like silver but it just simply solder used to attach it to a copper alloy wine vessel.
Is it gold plated or just oxidized silvering? Yes, in this case the artifact was gold plated.
Too many coin cleaners have a bit of confusion when it comes silver tinned coins. In most cases the silvering appears just a bit dull, as seen in the next example below.
All the yellow-looking bits are the silvering.