Tetradogma Posted July 31, 2023 · Member Share Posted July 31, 2023 Have a feeling I'm going to get told off..... So - this coin developed very aggressive bronze disease after a few months in my cabinet. It was surprising how rapid the growth was. Long story short I think my sodium sesquicarbonate/distilled water solution was out and it too aggressively stripped the patina. Good news the BD has ceased but the coin has suffered. I feel really bad about this, but it would have just continued and gotten worse if I hadn't done something. Would be interested in peoples thoughts. Please don't scold me too much. I read somewhere that baking can blacken bronze but Im leaning towards best leaving as is... Many thanks 5 Quote Link to comment Share on other sites More sharing options...
Benefactor robinjojo Posted July 31, 2023 · Benefactor Benefactor Share Posted July 31, 2023 (edited) Nice coin! I've seen worse effects after treatment. Some of the patina is gone, but the exposed metal will tone down over time, as it appears to have begun. Be patient and keep the coin out for observation. If you live in an area with high humidity, keep the coin in a dry location, possibly with a couple of silicon packs. Do you have the coin's weight before and after? I imagine the difference would be negligible. Edited July 31, 2023 by robinjojo 2 Quote Link to comment Share on other sites More sharing options...
Tetradogma Posted July 31, 2023 · Member Author Share Posted July 31, 2023 13 minutes ago, robinjojo said: Nice coin! I've seen worse effects after treatment. Some of the patina is gone, but the exposed metal will tone down over time, as it appears to have begun. Be patient and keep the coin out for observation. If you live in an area with high humidity, keep the coin in a dry location, possibly with a couple of silicon packs. Do you have the coin's weight before and after? I imagine the difference would be negligible. Oops, sorry, forgot to add info, pls see below. I did also bake the coin but not for very long or very high temp, enough to remove any residual moisture, as I was worried about what I'd done. That didn't make any visual difference. I have it stored with silica gel packs in the case. I think the previous owner had added something/filled areas, but that's just a hunch. Will give it a re-weigh, what's your thinking with that?? Thanks PONTOS, Amisos, Æ Time of Mithradates VI (Circa 85-65 BC) 7.9g, 23mm Obv: Bust of Amazon right, wearing wolf skin headdress. Rev: AMIΣOY./ Nike advancing right, holding palm frond and wreath SNG BM Black Sea 1218-9; HGC 7, 244. Quote Link to comment Share on other sites More sharing options...
ambr0zie Posted July 31, 2023 · Member Share Posted July 31, 2023 If the bronze disease was developing rapidly, I think your result is good and the coin still looks OK. 2 Quote Link to comment Share on other sites More sharing options...
Benefactor robinjojo Posted July 31, 2023 · Benefactor Benefactor Share Posted July 31, 2023 1 hour ago, Tetradogma said: Oops, sorry, forgot to add info, pls see below. I did also bake the coin but not for very long or very high temp, enough to remove any residual moisture, as I was worried about what I'd done. That didn't make any visual difference. I have it stored with silica gel packs in the case. I think the previous owner had added something/filled areas, but that's just a hunch. Will give it a re-weigh, what's your thinking with that?? Thanks PONTOS, Amisos, Æ Time of Mithradates VI (Circa 85-65 BC) 7.9g, 23mm Obv: Bust of Amazon right, wearing wolf skin headdress. Rev: AMIΣOY./ Nike advancing right, holding palm frond and wreath SNG BM Black Sea 1218-9; HGC 7, 244. In terms of weight, the loss of patina might have a material impact, but your coin is okay weight-wise. The BD on your coin seems to have been localized in a small area, and it's good that you caught it before it could spread. I've had to deal with coins having significant, and deep BD. The sodium sesquicarbonate/distilled water solution is almost a "nuclear option" when dealing with this problem. One coin treated this way, over an extended period, did loose patina, weight and is pitted where the BD ate into the surface. There's no BD now, but this was truly a Pyrrhic victory in this case. Quote Link to comment Share on other sites More sharing options...
Al Kowsky Posted July 31, 2023 · Member Share Posted July 31, 2023 Drink it off, it's only a coin. Quote Link to comment Share on other sites More sharing options...
Jeremy Posted July 31, 2023 · Member Share Posted July 31, 2023 Sorry that happened! At the end of the day, your results are better than the coin turning to dust, figuratively speaking. It's still an attractive coin. The exposed metal should darken over the years. I've had this result in coins I've treated where bronze disease underlaid the patina (sometimes completely). In one memorable case this was so bad the shiny black patina would flake off completely with light fingernail pressure. Now, I try to examine the edges of the coin before buying (as best I can from auction photos) to see if there's patina loss. It usually happens there first, which can be a symptom of deeper BD problems. Quote Link to comment Share on other sites More sharing options...
Orange Julius Posted August 1, 2023 · Member Share Posted August 1, 2023 Don’t feel too bad, it still looks good. I had a Diocletian tetradrachm and a M Tiberius follis with bronze disease I was soaking. The water all evaporated and the coins sat for a few weeks before I remembered them… well instead of dealing with the bronze disease… I only added fuel and made it worse on both coins. 😬 Quote Link to comment Share on other sites More sharing options...
CPK Posted August 1, 2023 · Supporter Share Posted August 1, 2023 BD is always a bummer but I don't think yours turned out bad at all. It's disappointing to lose an attractive patina, of course, but it's worse to lose the coin! Plus you can artificially darken the coin to help bring back the original appearance a bit. That's what I did to this BD survivor. It looked absolutely hideous after soaking - mottled and flat. The artificial patina isn't ideal but at least I can stand to look at it, now! 🙂 4 Quote Link to comment Share on other sites More sharing options...
Tetradogma Posted August 1, 2023 · Member Author Share Posted August 1, 2023 Thanks folks, making me feel better! Quote Link to comment Share on other sites More sharing options...
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