This coin of Valerian from Viminacium was being consumed by bronze disease. Every pit and depression was full of powdery green fuzz. It had a nice hard green patina on it but underneath the patina was the dreaded light green. It looked like the coin was being eaten up from the inside out. I was worried the whole fabric of the coin was riddled with BD. I tried soaking in Verdicare for several days. This had some effect, but the BD under the surface of the patina kept poking out again after a few days. Thinking I had nothing to lose I soaked the coin in a tablespoon of baking soda mixed with 50 ml of distilled water. This makes a pretty thick solution of baking soda. This baking soda ate all the green patina from the coin and did not totally remove all the light green fuzz. I cleaned as much off as I could, then resoaked it in Verdicare for a few days. After this, I brushed it with a soft brass brush and all the BD came off! Verdicare has the useful property of darkening coins making the lack of patina less ugly. I think the BD was working its way under the patina over the whole coin. Where there were holes in the patina the BD would show through. Removing it from these holes did nothing because the BD just came back. Nuking the whole patina exposed the BD where it could be neutralized. So now the coin has no patina but no BD either. It has been sitting on my desk for 4 weeks and the BD does not seem to be coming back. Not the prettiest coin but I think it has been saved from complete destruction. I plan to soak in distilled water a few days, then cook in the oven at 220 for 2 hours and then rennwax it. I don't usually use rennwax but I think in this case it is prudent. If BD is under the patina on your coin, you may need to do something similar to save it??? Post your experiences with BD both positive and negative. John
Even ugly coins need to be saved. Did I say ugly? I meant visually challenged. Seriously, good job. You have more patience than me.
theodosius, i don't think i would renwax it. maybe another coat of verdi-care? here is BD growoing under wax, several months after application. i guess at worst, you'll just have to remove the wax to treat the BD if it does take off again. happy ending so far, i removed the wax, treated with distilled water and baked AGAIN...then applied verdi-care. here is how it looks afterwards, and still does over a year later.
In Sept last year I ran this thread on a coin that had bronze disease https://www.cointalk.com/threads/my-first-case-of-bronze-disease.283504/ I won't go into to much depth on it here only to say that I am happy with the results on my soaking for months Sodium Sesquicarbonate (bi-carbonate and soda ash) mixture, actually increasing the strength as time went on as it made the green patina so patchy I had to strip the whole lot off, and then baking and Ren wax. Below are pics of the coin, first when I received it (only $64) and mid-way, then final light brown patina. Warning Theodosius threads on this subject can become monolith.
Hopefully it stays away, but I would let the Valerian go, cheap ebay sell, YN freebie or something. I have embraced Potin Tetradrachms lately, I still watch them more closely than my other coins.
I had a patch about the size of my thumb on BD on a sestertius. At first I just cleaned with water and my thumb and sat it on a heater to dry but it came back. So I cleaned it the same way but fallowed up with some alcohol pads and baked it at a low level. Never cam back. Also had a similar experience with a Godian III Ant.
My Valerian bridge type had BD in the past and has left a couple of craters. VALERIAN. CILICIA. Mopsuestia-Mopsus. Valerian I (253-260). Ae. Dated CY 323 (255/6). Obv: AVT K OVAΛЄPIANOC CЄB. Radiate, draped and cuirassed bust right. Rev: AΔP MOΨЄ / ЄT ΓKT / Δ - Ω - Ρ - Є - Α / Π PAMOC. River god Pyramus, holding cornucopia, reclining left on river bridge consisting of five arches; triumphal arch at left and right end. SNG BN 1998 var. (rev. legend); Price & Trell 639 (fig. 83). Condition: Very fine. Weight: 14.43 g. Diameter: 31 mm.
