My first run-in with bronze disease

[Captch]

I just had my first case of bronze disease on a Maxentius follis. I've ordered sodium sesquicarbonate and picked out the green spots the best I could with a steel pick, but I just feel down. Does anyone have some bronze disease success stories they can share to cheer me up?

[Limes]

It hurts when your coin gets a case of BD, but successfull treatment is possible! There are several topics on this matter with a happy ending, posted on this board. See e.g. this topic by Roman Collector. And here you may find my personal experience. And here's an excellent topic about it on cointalk as well. 

Be sure to share photo's and your personal experience too! 

 

[John Conduitt]

I left mine in distilled water for a couple of months, changing it every other day, and it hasn’t come back in 2 years. You do lose a bit of metal but if the spot is somewhere less intrusive you still have a good coin.

[CPK]

It's a pain, but it can be cured. Lots of patience is needed!

@Limes linked my experience with BD on CoinTalk, but the thread is also here on NumisForums as well: 

 

[Ancient Coin Hunter]

I have a trachy of Manuel Comnenus which somehow got the bronze disease between the time when I purchased it, roughly a year ago and a few days ago when I saw it in my collection. I attribute it perhaps to a moister environment and the fact that it was stored in a plastic flip. I have yet to treat it but I suppose I will try distilled water.

[ewomack]

I have a bottle of VerdiChem, but I (thankfully) have yet to use it. I hope that I never do.

[Marsyas Mike]

Over the past year I've been trying to tackle some of my own BD problems - all I use is distilled water soaking and a steel pick (from a skin care kit!).  Here is an Egyptian drachm I recently worked on.  I thought it came out pretty well, considering my lack of expertise and chemicals and manual dexterity and close-up vision:

It may require more attention, but at a certain point, the green stopped coming off.  So I'm going to keep an eye on it, see how stable it is.  Working on these has actually become a kind of enjoyable pastime for me.  So good luck!  

 

[seth77]

What worked for me for mild cases of BD was picking the spots they heat-treating the coin both under direct flame and in a gas oven for very short periods of time - 10-15s under direct flame and 1-2hr in the pre-heated oven. I have also used the baking soda and lye solution but found that it alters the look and surface of the coin substantially. Since BD seems to be triggered by humidity, taking humidity out of the coin as thoroughly as possible seems to help a lot.

[Captch]

Okay, time for a write-up.

I purchased my BD coin on February 16, 2023. This was the photo with the listing.

It's a pretty typical Maxentius bronze. I received it on February 22. I like to take my own photos. This photo shows it was last edited on February 24, so I took the picture and edited it right when I got the coin.

The keen-eyed among you might be able to spot the problem: The little speck of white between the columns to right of the Roma statue in the temple.

 

On April 12, when I made this post, I was futzing around with my coins and was horrified to see this on the reverse:

There is BD between each column on the right as well as between Roma's knee and foot. I picked out what I could with a steel dental pick and returned the coin to its tray for the time being. Two days later, my BD treatment had arrived, but the BD had come back. Here is how the coin looked on April 14th after being scraped clean on the 12th.

On the 14th, I prepared a 4-5% (by mass) solution of sodium sesquicarbonate. I again picked out the green bits with my dental pick and then put the coin in the cleaning solution. After a day, this was the result.

The spot of BD by Roma's leg seems to have been cleared up, that's bare metal. There are still spots in between the columns that I couldn't get my pick in. On April 20th, I was satisfied with the results and worried about damage to the rest of patina. I removed the coin from the solution and put it in a toaster oven at 150 degrees F for half an hour to dry it. Here are the results of the treatment on the obverse

and reverse.

Unfortunately it looks like some of the finer detail on the reverse lettering has been worn away, but I'm pleased with the result. The coin is definitely darker, but I also didn't light the coin the same way as the before pictures. I left the coin out in the kitchen as I made diner and did dishes yesterday - two things that I imagine make it pretty humid in there, and the coin looks fine this morning. I assume over the next few years it will repatinate. Overall, I'm pretty pleased with these initial results.

[CPK]

Looks good. Make sure you keep an eye on it though!

Do you live in an area of high humidity? Seems like it came back awfully fast!

[Captch]

4 minutes ago, CPK said:

Do you live in an area of high humidity?

I live in western Oregon. It rains from October until May. It's not ever humid humid like summers growing up in the Midwest, but it is always wet outside of summer, if that makes sense. I live in a small apartment with no AC, so there's nowhere for warm wet air from cooking or showering to go - except to the temple of Roma!

[Captch]

I guess I will also note that I probably wouldn't have caught the BD if I didn't have trays. They're pricy and annoying, but they are the best way to show off a collection 😛

[idesofmarch01]

5 minutes ago, Captch said:

I guess I will also note that I probably wouldn't have caught the BD if I didn't have trays.

Here's a quote from Wikipedia's article on bronze disease (https://en.wikipedia.org/wiki/Bronze_disease):

"As it relies upon the presence of chlorides, water, and oxygen, the absence of one of these three halts the progress, although any damage done is irreversible."

(The emphasis is mine.)  It's not the displaying of your coins in trays per se that caused the bronze disease to progress, but rather the exposure of the chloride ions to oxygen in air.  It's my understanding, then, that if you've completely eliminated the chloride ions using the sodium sesquicarbonate solution, picking, and heating, then you do NOT have to worry about the return of bronze disease even if you expose the coins to air by displaying them in trays.

The Wikipedia article is quite good and requires only a knowledge of high school chemistry to understand the process.

[Captch]

@idesofmarch01 I meany I look at my coins more often since they're in trays rather than in boxes. This coin isn't my favorite of the collection, so it's likely that I wouldn't have seen the BD in time to stop it.

[Captch]

It's back... and it's coming for the wreath in the temple pediment, which is one of my favorite parts.

I'm leaving on a trip for a month, so I'm soaking it in distilled water for now 😞

[Captch]

I had a change of heart and mixed up another 5% solution and will leave it in there for a week before my wife changes it over to distilled water.

[mc9]

Keep in mind that the process leaves a blue mark on your coin, difficult to remove.

[Captch]

Alright, I pulled the coin out after two weeks in sodium sesquicarbonate and four weeks in distilled water and haven't seen a recurrence of BD spots. Because I gave it a few week soak in DW while I was gone, the grey-blue residue left by the chemical solution came off with gentle brushing with a toothbrush. I have attached pictures of the coin before I brushed it. I have a dehumidifier set up near my coin tray now. If all went well, I just have to wait a few years for a patina to form again...

[Theodosius]

Bake it in the oven at 200° for an hour. Then store it in an airtight container like a Ziploc bag with a desiccator bag in it. Otherwise it is likely to keep coming back until your whole coin is destroyed. You can bake your desiccator bag at the same time as the coin. The best ones have a little color indicator that shows when they are saturated. You can also buy very cheap digital hygrometers on Amazon for a few dollars. I bought a set of 20 of them and keep them in each of my air tight containers along with my infected coins. It really helps to have numerical measurements of the humidity of the environment you're storing them. Otherwise it's just a guess. Usually 40% humidity or less is safe. BD will be active at 50% or more. Good luck.

John