Hello all, I've recently acquired this 1/2 Punic Shekel from an older friend who won it from a european auction a few years ago. The coin is in relatively good shape but there appears to be some reddish deposits on both the obverse and reverse of the coin, I've read that these could be either iron oxides, copper oxides or cuprite, I've successfully removed black iron oxides (horn silver) from coins in the past using the Sodium Thiosulphate method devised by @Roerbakmix which always worked. Using that method on this coin did not help much with the reddish deposits, if these deposits are in fact copper oxides than I would need a different procedure. I've read that a combination of vinegar + salt can eat away at copper oxides but I just want to be sure if this would be recommended for silver coins since this solution is slightly acidic. If I were to create this solution, would the tempreture of the solution matter? Should I make it at room tempreture or should I heat it up in the microwave? Here are some magnified photos of the deposits,
@ArtDeco - nice half shekel. These were struck at an uncertain southern Italian mint during the Second Punic War. Here is mine: Carthaginians in Italy AR 1/2 shekel 215-210 BC 3.53 g, 18 mm, 12h O: head Tanit left R: horse standing right, sun disk above, Punic “TH” below HN Italy 2016; CNP 42a It seems these red deposits are more common on billon coins, but these 1/2 shekels were >90% silver. My understanding is these red deposits are difficult to remove and the surface will be pitted. I have no experience trying to remove them, but here is a previous thread on the topic: https://www.cointalk.com/threads/wh...ng-hard-red-deposits-on-a-silver-coin.386573/ From the image of the reverse, I personally don't think the deposits are too distracting overall as the major design features are still clear. It looks like it in nice condition and I assume the obverse is OK. My inclination would be to leave it as is, but I would also be interested in what others think.
@ArtDeco The reverse looks good to me. The red deposits are interesting, and a sign of the age of the coin, and a sign of the environment where the coin was buried, and a sign of authenticity. If it were my coin, I would leave it as is. Do you have any photos of the obverse?
Thanks for the replies, I've owned a few 1/4 Shekels from the 2nd Punic war but never a 1/2 Shekel. If you ask me it is definitely cool to have something closely associated with Hannibal Barca, very cool coin and nice centering on yours @Silphium Addict Here are quick photos of the Obverse and Reverse of the coin, the coin is actually not as porous as it looks in the photos, I over cropped the photo and it looks a bit blurry. The reddish deposits aren't a massive issue but it would be nice to remove them if I have a safe way of doing it without damaging the coin. There is some decent toning on the coin also that might disappear with acidic methods, so I might like to avoid that.
That's a very nice example, well centered and with excellent detail! My experience with these almost rock hard brownish and greenish deposits is that they simply do not yield to any cleaning processes easily. The way these deposits are structured, somewhat softer material is at the top and much harder material is under, near the surface. So, cleaning becomes a matter of compromise in this instance. I agree that it is good to have some deposits on an ancient coin; it is, after all, not a Morgan or Peace dollar. Some collectors/dealers sometimes get carried away and over clean a coin. This is especially true for coins with horn silver deposits. While it is nice to have a bright ancient coin, often these deposits mask corrosion underneath with the result that the coin is bright and pitted - not good. Looking at your coin, I would leave it as-is. Remember, with time the coin will darken, with the silvery areas blending more in with the deposits, which I think are cuprite. Here's a billon tetradrachm that was my last cleaning project. It is a coin of Hadrian, Alexandria, with Nilus on the reverse, a relatively common coin. The main area of focus was on the obverse. There the deposits were quite thick and hard, obscuring much of the center of the portrait. This is a photo (somewhat blurry) from the seller, before cleaning: The cleaning of this coin was a protracted process using naval jelly, heated citric acid (lemon juice), distilled water, gentle mechanical removal with wooden tooth picks and frequent inspections. Initially, I also had to use 100% acetone to remove what appeared to be some kind of clear lacquer. After a few days I reached the point with this coin where enough is enough. Deposits remain, typical billon graininess is present, and the overall color is a medium grey, which will darken. Hadrian BI tetradrachm, Alexandria, Yr 20 (135/6AD). Emmett 879; RPC III 6090 24mm, 12.85 grams So, cleaning, as with many things in life, is a matter of compromise and being happy or at least content with the results.
I've also had success removing some of these reddish deposits off of third century antoninianii using heated citric acid after reading @Roerbakmix's posts. They weren't as significant as yours but removing them made the coins look a whole lot better. The key is not to leave them in the hot citric for long (20-30s at a time) as it is a weak acid and prolonged exposure may eat away at the coin.
Thanks for the suggestion and glad to hear you had success, I'm now in the middle of soaking the coin in a sodium thiosulphate solution for at least a few days, if that doesn't help then I will try the heated citric acid method. Is it literally lemon juice straight from a lemon or lemon/lime concentrate heated in the microwave? How long would you heat it in the microwave for? Thanks!
Wow, that is brilliant. Thank you for your examples, this is great information for the conservation side of the hobby. Of course like you said, sometimes it is best to leave the deposits as it is and just let the typical atmospheric sulphur reaction darken the coin to blend with the deposits.
The 1936 Dorchester Hoard coins (mid-3rd century Roman AR Antoniniani) often have those red deposits: I've left mine alone (as previous owners did for ~85 years!), though I'm sure it would be easy to smooth them down a bit. Here's an example: I bought a few AR Antoniniani a few years ago with only a recent Canadian collection history, but they still had some degree of similar red deposits. I wonder if they might also be from the Dorchester Hoard? (These types were in it, but it was too big to record individual specimens; in principle, though, there's information in the patina.) I have a couple of Carthaginian EL Staters (c. 300 BCE, give or take a couple decades) that have much more minor deposits, but similar. They're small, but you can see them in a few recesses on the reverse (and a couple spots in the fields on the obverse) -- look especially around the horse's legs & face/neck: In hand, they have that typical rough, reddish-brown quality. One sees that on a lot of the specimens that came onto the market in the 2010s. It may or may not ever be possible to connect any of the coins to a single deposit or findspot. But they don't bother me, and add the potential of preserving some information.
@Curtis - nice Carthage El shekel I have seen similar red deposits on some of my Carthaginian AV/EL coins that appears to be different from the hard red deposits of the silver coins in this thread. I also usually leave them alone. However, here is one of my Carthage gold coins that I was able to easily remove the red deposits with distilled water and a toothpick: Original auction image My image after cleaning Carthage AV 1-1/2 shekel 264-255 BC 10.28 g, 12 h O: head Tanit left R: horse standing right with head tuned back left J&L group IX 383 Initially, I decided to remove just a few of the larger deposits I found distracting, like right under Tanit's nose and around the lips. However, they "flaked" off so easily that I removed the others, but you can still see traces of where some were because I did not want to chance damaging the surface. I think the deposits on my coin were most likely residual soil since they were all in recesses instead of corrosion like on the silver coins. This coin is almost certainly an unrecorded example from the Tunis 1948 hoard IGCH 2271. Supposedly, all coins of this type (except one in the BnF) are from this hoard.
Stunning 1/2 EL Shekel, I don't think I've seen this denomination in electrum for Punic issues before. So did you just soak the coin in distilled water for a few days and then started removing the material with a toothpick or was it done while the coin was in the distilled water?
I have news folks! After a 48 hour soak in the warm/heated sodium thiosulphate solution, I decided to take it out of the solution and wash it with hot water.......and to my suprise, it looks like some of the deposits are gone! I then took a wooden toothpick and wondered what would happen if I tried to remove the deposits in certain areas and looks like the material slowly came off the coin! I guess what happened was that the reddish deposits started softening up in the heated sodium thiosulphate solution as some of the iron oxides that were in the mix were breaking off the deposits, weakening its hold onto the coin. I guess all I needed was a longer soak in a heated solution and patience for the deposit to soften/weaken.... I tried my best to remove all the deposits off the whole coin but some tiny spec of areas are still hard as a rock and won't budge, I used my illuminated handheld magnified lens to help me view the areas while I was removing material with the toothpick. I also had a small bowl of warm water to constantly dip the coin in it once I removed material and then I focused on other areas of the coin. Overall, the majority of the reddish deposits are gone save for a few specs throughout the coin and there isn't that much in the way of pitting from the areas I fixed, so I can also say I'm quite lucky. Here is the coin now! (sorry again for the bad lighting)
@ArtDeco Wow! Dramatic improvement. In the photo, the surface where the deposits were looks the same as the rest of the surface. The coin looks much better. Congratulations! For your previous question, I had soaked in distilled water then used toothpicks while coin still wet.
@Silphium Addict Thanks! I'm just glad I could get the crud off this cool coin! This may be off topic but how do you take proper photos of coins? Do you use one of those microscope camera tools on Amazon or do people have a specific technique?
Looks like great results on the cleaning! Thanks for sharing the results & process The lighting is a bit different so I can't tell for certain if there was any impact on toning or surface texture (those would've been my main concerns), but it looks like good news. @Silphium Addict : wow, what a great 1.5 EL Shekel/Stater! I've never handled one but those extra-large 10.3g electrum flans must be impressive in hand!
