This is a long post, I hope you’ll find helpful. When a Ptolemy AE47 87 gram “hockey puck” in good condition appeared on VCoins earlier this year at a very good price, I jumped on it. Ptolemy III Octobol Alexandria 47 mm 87.47 gms Obv. Head of Zeus, right Rev. Eagle standing, right, club before Ref. Svoronos 446 Isn’t that a beauty? I won’t mention the dealer or show the VCoins photos because I don’t want to name and shame: I’m sure the dealer would have accepted a return, but I never asked for one. What apparently happened on the long trip across the ocean, and possibly even longer trip through customs, was that bronze disease erupted. Rather than return it and risk it being destroyed, I decided to try my hand at saving the coin. It turned into quite an adventure. The first step was to clean the coin. I gave it an acetone wash to remove hand oils. This should have been a trivial step, but what happened was a lot of putty-type filler softened and then rubbed off when drying the coin. Someone had applied what looked like cosmetic foundation to the surface of coin to hide casting pits and other defects, including additional areas of active bronze disease. Maybe I should name and shame. Just kidding. The next step was a soft bristled toothbrush to remove the loose bronze powder. It came off easily and there was a lot of it. A lot of dirt and putty came off as well. Whoever prepped this coin didn’t care about it at all. Next step was a bamboo skewer to remove any remaining visible bronze disease. I was in for another surprise when the casting pits visible on the obverse — see photo — turned out to be active bronze disease reservoirs. Someone had dyed those areas a dark brown, but beneath the dye was active bronze disease that had etched out a larger pit than it appeared. With the help of a microscope, I scraped those areas clean. At this point I was having second thoughts about not returning the coin. But I carried on. It was now ready to soak in sodium sesquicarbonate. I bought the powder from Amazon, along with a graduated liter bottle and a small mason jar. I mixed a 5% solution, by weighing 50 g and adding it to 1000 ml of water. Easy peasy. Go metric system. Taking care not to get hand oil on the coin, I wiped it with the fluid on a q-tip to prevent bubbles and dropped it and watched intently, expecting it to at least fizz or something. Nothing. Darn. I planned to let it soak two weeks, but when I checked it an hour later, the solution was a dark blue. The British Museum changes the solution when it turns blue, so I changed it. I changed it eight more times that day. The next morning the solution was blue, but interestingly no bluer than it was after an hour or two the day before. I took this to mean the reaction was complete, and leaving it sitting in what was essentially blue water wouldn’t do anything good for the coin. I tested this later, but it turns this assumption was basically correct. I changed it every few hours for the next couple weeks, before it finally settled down to once a day. It stayed at once a day for the next three months. Aside from burning through a ton of sodium sesquicarbonate, not much seemed to be happening as far as the bronze disease was concerned. The coin was still largely light green on both sides. I’d read that this process would strip patina, but that was only somewhat true. Certainly the surfaces had changed color, darkened mostly, and the white and orange had dissolved away, but as far as the harder dark brown patina was concerned there didn’t seem to be much change. Fast forward three months of soaking, eventually reaching the point where I could change the solution every two weeks, and by then much of the light green was gone. At this point I forgot about the coin, and it sat for over a month in solution. Something fascinating happened, and I wish I’d taken a photo of it. Rising above the pits where bronze disease had been most active, were plumes of darker fluid in the solution. They looked like little blue tinted tornados rising from the pits. Apparently the disease was still active in there, and the plumes showed there was no real mixing taking place. Most of the fluid was contributing nothing. I dug the pits out again with a bamboo skewer, and put it back to soak. A month later the solution had not changed color, and all I had done was swish it around occasionally to get fresh fluid in contact with the coin. I took the coin out, gave it a distilled water rinse and soak, and left it to dry. After two weeks it hasn’t changed. Here’s the final result: It still isn’t a beauty, but at least it isn’t dissolving away anymore. The light green areas that look bronze diseasy are actual quite hard, so I don’t expect the disease to erupt from them. If it does, I’ll repeat the process again. The best part for me is the cleaning revealed that someone in ancient times decided Zeus looked puffy cheeked, and graffitied lines to make it look like he was blowing. I just love that. Banksy would be proud. People haven’t changed much in 2000 years, have they?
Well, you almost lost me at "This is a long post,...", but I went along anyway. This is what I love about this hobby - the passion we have to learn & preserve history! To me, it looks like you had satisfactory results, considering what you started with. My only question is, do you believe this is the same coin you purchased on V-Coins? You stated that "When a Ptolemy AE47 87 gram “hockey puck” in good condition appeared on VCoins earlier this year at a very good price, I jumped on it.". I just don't see this as a "good condition" coin, so wondering if it was a bait & switch.
Nice save! I think it looks like a nice coin now. It was on the way to total destruction before. I would watch it carefully for six months now. John
Many people don’t use good for ancient coins, but it seemed the most apt grade to me. I won’t argue if you think it’s fair or even poor. No bait and switch. I don’t doubt the green and white corrosion occurred in transit. I only paid a bit over $50 for this huge bronze, I have no complaints.
That is an impressive save. And your description was well-written - long technical descriptions quickly overwhelm my brain and patience, but I found myself reading this with considerable enjoyment. I do wish I had your patience - the end result was well-worth it. I must say I was shocked by how much "improvement" this coin was subjected to before you bought it - all that filler and camouflage. Especially coming from a Vcoin dealer.
Honestly, I was too. I’ve worked with the dealer in the past and don’t question his motives. I can only speculate, but I think someone found the coin, tried to hide the bronze disease and improve the appearance with putty and dye, the disease erupted through the cosmetics before they could find a buyer, so they gave it a quick brush and slapped an orange and red caliche on it for a quick sale to the dealer. On the way to me the bronze disease erupted again and here we are.
Solid rescue operation. The coin looks better than I thought it would at the end. I was about to say that was kind of a pricey coin to choose to experiment on, but then I saw you only paid $50. Makes me real glad my Ptolemy octobol has a nice, hard, green patina to protect it.
Well, here's an eBay story for you. An Antoninus Pius sestertius with the most interesting blue patina. A day or two after I got it, the "patina" became sticky to the touch. A dab of hand sanitizer and the truth emerged - a harshly cleaned, mostly, patina-free coin (but no bronze disease, thank goodness). It was only $10, which I would've paid anyway (the reverse is very worn, but it has the emperor in a slow quadriga, a better type I think). Funny what modern people do to ancients. Before and after (I left traces of blue in the declivities for posterity):
