When I got into bronze I decided that every year I would do an inspection of every bronze piece and billon piece with low silver content. On top of that I've given every bronze coin an annual light application of Verdicare, and I'm happy to report they are al BD free...except for this one which I never bothered to apply any Verdicare to. China - Xin Dynasty. Wang Mang AE. Bronze Huo Bu (9-23 CE) Hartill 9.30 Well, big mistake, I should have used the Verdicare on it like every other bronze piece. Yearly inspection revealed a tiny blue green spot, and upon a finger nail test, it proved to be powdery. Look how tiny it is, looks like I caught it nice and early. I have removed the remainder with a toothpick and have now applied Verdicare to the entire piece. I will keep isolated and inspect every week for 3 months for signs of reappearance, and treat with other means if it dares show it's ugly face again. There appears to be no visible damage as I caught it in it's early stage. Inspect your bronze and billon coins at least once a year, and change the envelope or holder. And Verdicare is your friend. Don't leave the protection of your bronze and billon coins up to pure luck.
..sound advice big O.. i found a place on one of my bronzes also a few days ago and used a toothpick supplied by badthad with a dose of verdicare on it..
Only one of my coins had caught the dreaded bronze disease - a follis of Galerius and one of the oldest coins in my collection (30 years). I scraped off the powder with a toothpick and applied a bit of olive oil and rubbed it off. Hasn't returned. I have to look into verdicare.
While I can't scientifically prove without a control sample and controlled conditions that the verdicare is the reason my other bronzes didn't have any BD, I do find it interesting that the only coin I didn't apply any to is the one that managed to get some BD in the past year. I've also had verdicare work wonders on a bronze coin that I once accidentally dipped in acetone instead of a second container that contained only distilled water (bad judgment on my part having two identical glasses containing the two liquids right next to each other). The coin looked rather dull and lifeless after the acetone dip, but to my relief a touch of verdicare brought it back to almost exactly how it looked before the accidental acetone bath. I heard verdicare can also be used on silver coins to stop toning, however I like my silver dark so I've only used it for my bronze and billon coins.
Alrighty, I just put in an order for the economy bottle and will be putting this stuff to the test. I have a Sicilian Tetras that is just nasty with BD. I will try this stuff out on it and report back before and afters. Other than using a toothpick to clean away the nastiness and then applying the Verdicare any other tips? I post this image with the STRONG WARNING: THE IMAGE YOU ARE ABOUT TO SEE IS NOT FOR THE WEAK OF HEART NOR STOMACH...
Hurts to look at, I know. I bought it for cheap and have tried to clean that junk off. But it just keeps creeping back...
You need to get rid of all the BD before applying the Verdicare, otherwise you run the risk that it will continue to grow under the Verdicare film. Spend an extra $1.50 on a gallon of distilled water. Use the toothpick to remove all the BD. Soak the coin in a cup of DW for 2-3 days, then empty, dry it off, and replace the DW with fresh and repeat this procedure for around 3-4 weeks. Then let the coin sit out someplace where you will see it often to make sure the BD doesn't return. If it comes back, just repeat this series of DW soaks. If it hasn't returned after 3-4 months, then you can be certain you've removed all trace of it. Only then should you apply the Verdicare. I have treated many coins with BD using DW soaks. 95% were cured with just one series of soaks. A few required a second treatment. I've never had a coin that needed a third.
I've treated a number of coins for varying degrees of BD. I think @gsimonel's advice is best. You definitely need to debulk the BD before applying Verdicare. An alternative to distilled water soaks is to soak in a sodium sesquicarbonate solution which you can approximate with a mixture of baking soda and washing soda. If you're the patient sort, try the plain water soaks first. I've had a number of coins as bad or worse than yours, usually from large lots. While I'd rather not have any coins with BD, it's something you have to deal with if you collect bronze, billon, and potin coins. You acquired this coin cheaply and now you're getting some experience with BD and its treatment. Nothing wrong with that
I've heard about sodium sesquicarbonate. From what I've heard, it's a very effective treatment but the chemical is fairly toxic and has to be handled carefully. If you can get the same results by combining baking soda and baking powder--which would be much safer to handle--then that might be worth trying, too.
I corrected a hasty mistake in my first post. Baking soda + washing soda yields sodium sesquicarbonate. By approximate, I meant that most people don't have reagent grade baking soda (sodium bicarbonate) and washing soda (sodium carbonate) nor do they have means to accurately measure the proportions to create a ~5% solution of sodium sesq.
I've had decent luck with the distilled H2O & verdicare . Have also had to use the baking soda & ash method. @Sallent I know your collection is much larger than mine and can understand it's time consuming but I try to give my "bronze" the look over every 3 months and the serious check about every 6 months. Obviously I look everytime I have a coin out to enjoy I have also kept treated coins seperate from other coins for up to a year. I don't recall were I got the time of a year separation from and not sure if that's being overdramatic, but nobody wants to deal with a bad case of the dreaded BD, I'm sure.
As I look at the coin a second time, I wonder if it's really bronze disease or if it's just a mostly-lost green patina. Is the green spreading? If you let the coin sit for a few days, do you see the green spots building up into tiny piles of green powder? If yes, start treating ASAP. But if the green spots are just sitting there and don't brush off easily with your finger, it's probably not BD, and you can relax. And if it turns out that it's just a splotchy patina, you might consider electrolysis.
I wish it were patina. It it's powdery and has spread after cleaning. I just finished cleaning it off with a toothpick and it is and will be sitting in distilled water for the next 3 days before I dry it and give it another round. In regards to drying, I've read baking the coin after cleaning helps. Good idea or too extreme?