Oh no!!!! Is this what it looks like?

Discussion in 'Ancient Coins' started by Julius Germanicus, Sep 1, 2020.

  1. Julius Germanicus

    Julius Germanicus Well-Known Member

    IMG_20200901_115854.jpg I received this Sestertius from an auction house half a year ago and it seemed perfectly fine then.

    I luckily have no experience with the dreaded bronze disease yet - but this sure does not look good to me. There is a green powdery substance coming off when rubbing it with a cloth.

    What should I do now?

    Last edited: Sep 1, 2020
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  3. paddyman98

    paddyman98 Let me burst your bubble! Supporter

    Unfortunately your picture does not show.

    Now I see it.
    Last edited: Sep 1, 2020
  4. Co1ns

    Co1ns Active Member

    Put it into distilled water by itself, change the water every few days until the green powder is gone completely, then change once more and leave.

    This will at least halt the reaction as long as the coin is immersed.

    I have had tentatively good results treating with lye, but the coins I've treated have only been disease free for a week or so now ... I've gotten to this point with distilled water then oven bake before, only to see it come back.
  5. Julius Germanicus

    Julius Germanicus Well-Known Member

    Thanks! I fixed it :happy:. The sight was just too shocking for me...
  6. gsimonel

    gsimonel Well-Known Member

    I would not use lye. Distilled water (DW) should do the trick.

    Change the DW, (~6-8oz), every day or so., and continue doing this for at least 2-3 weeks, long after all the green has disappeared. You need to make sure that all the chlorides have been removed. All together, you'll probably end up using between 1/2 - 1 gallon of DW.

    Once finished, you should let the coin sit out exposed to air somewhere you are likely to see it often for the next 2-3 months to make sure the bronze disease does not return. If it does, it means some traces of BD were left behind in the metal, and you'll need to repeat the treatment. I've had this happen to about 5-10% of the coins I've treated, but I've never had the BD return after a second treatment.

    This is a long, drawn-out process, but it's quite simple, cheap and painless, and it has always worked for me; it just requires a little patience.

    Some members have reported success using sodium sesquicarbonate. This may be faster, but I've never tried it, so I can't say for sure.
    capthank, Broucheion, Chris B and 8 others like this.
  7. fomovore

    fomovore Supporter! Supporter

    I remember reading positive reviews of using deionized water (it should work better than distilled since it has almost all minerals removed) until any traces of residue are gone, baking the coin in an oven hot/long enough to evaporate all moisture (but not hot enough to damage/discolor it) and then applying renaissance wax or similar.

    I wouldn't use lye - it can discolor.
    Last edited: Sep 1, 2020
  8. gsimonel

    gsimonel Well-Known Member

    Yes, I have heard that some collectors bake their coins after treating, usually at around 200-225 degrees F for around 1 hour. As long as the temperature is low, it shouldn't harm the coin, and it probably does speed up the drying process.

    Do not put Ren wax or any other sealer on the coin until you are absolutely certain all the BD has been removed, or you might end up trapping the BD inside the coin, making it impossible to get to if you need a second treatment. So wait about 2 months before you add any wax.
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  9. Co1ns

    Co1ns Active Member

    Both lye and sodium sesquicarbonate will strip patina given a long enough soak in strong enough solution, the latter will take longer to do so. Distilled water definitely the safest option.

    On other hand I have seemingly removed BD without any damage to patina/discolouration after a quick lye soak. Definitely not something I'd recommend experimenting with on a valuable coin, but definitely something I'll keep experimenting with on less valuable ones.

    Interesting about deionized water, might be more effective on crusties too.
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  10. Macromius

    Macromius Well-Known Member

    Nowadays if I see surface BD I gently scrape it off, or pick it off with a toothpick, bake the coin in the oven on a piece of foil at about 350 degrees for 30 minutes. Then before it completely cools I apply verdicare. I don't even think about using distilled water or sodium sesqicarbonate unless it's a really bad case. (Lye?! I only use that when I have to dispose of a body.) I've learned that less is best but whatever works for you is ok by me.

    When I started collecting ancient coins no one told me that they were like pets or plants that I had to watch carefully and treat for illnesses. Sheesh!
  11. gsimonel

    gsimonel Well-Known Member

    Back when I was in college, I was able to get deionized water from our geochemistry lab, and it worked very well for cleaning coins. The problem is tracking it down. I've seen it sold as some kind of exotic sports drink (which is stupid; $5 for 20 oz. of water!?!).

    Basic distilled water (DW), which you can buy from any grocery store for around $1.50, is just about as good. So if you don't have access to deionized water, don't worry. DW is fine.
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  12. Co1ns

    Co1ns Active Member

    Interesting. Yeah I had a quick google earlier and didn't seem to be readily retailed like DW is, you'd probably have to procure it from chemical suppliers in bulk.
  13. gsimonel

    gsimonel Well-Known Member

    Yes, deionzed water is best, but DW is still good.
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  14. Co1ns

    Co1ns Active Member

    Yeah after you saying how much DW you use to treat BD, I'm thinking I might be being a tad stingy with my volumes for cleaning.

    I tend to have 10-20 coins in a cm or two of water and it definitely works, but I guess the more volume you have, the more minerals absorbed before the solution becomes saturated.
  15. gsimonel

    gsimonel Well-Known Member

    I'm surprised that you have that many coins with bronze disease. BD is not very common. Are you sure it's BD?
  16. Julius Germanicus

    Julius Germanicus Well-Known Member

    This is the only one of my 100 Sestertii that shows something like this.
    No one has answered the question yet IF this is really BD but thank you all all for the ideas on how to cure it! I´ll first get DW tomorrow and let you know the results.
  17. gsimonel

    gsimonel Well-Known Member

    If you can easily brush it off with your finger, it's likely BD.
  18. Co1ns

    Co1ns Active Member

    Sorry I'd gone off topic and was just talking about cleaning, but referencing the quantities of DW you suggested for treating BD - I think 2000 year old calcified concrete may warrant similar quantities, rather than my stingy shallow soak.
  19. Kentucky

    Kentucky Supporter! Supporter

    Distilled vs deionized water... I just Googled this so I could include a link, and the first response was such nonsense, I thought I would air my thoughts/opinions. Distilled water is just what it says, water is boiled and the resulting steam is condensed. This is "pure" water from the standpoint that it doesn't have any non-volatile contaminants, it can still have dissolved organics that would co-distill, and it can have dissolved gases present either before or after the distillation. It should have little to no electrical conductivity and leave zero residue upon evaporation. Deionized water, on the other hand, is water that has been put through a resin bed (think of water going through ground coffee in a coffeemaker) that would remove any dissolved salts (and any extraneous solid material...after all, it is a filter) but would not remove any dissolved organic material, liquid or solid. The deionized water would have little or no electrical conductivity, and, if the beginning water wasn't bad, should have zero residue on evaporation.
    Last edited by a moderator: Sep 3, 2020
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