Treating BD on a on a Antoninianus with little to no silver?

[Jschulze]

Hello all!
I'm looking for advice on how to treat this BD on this seriously debased silver or straight bronze Trebonianus Gallus Antoninianus. I've read a ton of posts but have gathered that treating debased antonini can be tricky and lead to ruining coins. I don't currently have any specialized chemicals like GG BD killer so I was hoping to find a effective but safe home remedy if possible. Would the typical treatment methods for bronze be safe here? I'd like to keep whatever patina is currently there too if possible. Any suggestions? Thanks!

Josh

PS: I'm also looking for more details on the coin in an identification thread. Thanks!

https://www.forumancientcoins.com/board/index.php?topic=97585.msg602839#msg602839

[bruce61813]

BD killer or Gringgots #1 will work. If the BD has not worked under the silvering the coin should be safe. I would us some mechanical cleaning methods, a sewing machine needle and magnifier come to mind, first, then a short test soak, say one hour at room temperature. The green copper oxide will dissolve, and a soft brush with an old toothbrush. See how that looks. Go easy and slow.


Bruce

[Jschulze]

Thanks Bruce for your expertise! I'll give that a try. Fearing causing damage, I've put it aside to monitor it since it arrived a few months ago. Nothing has progressed so I'm wondering if the BD is inactive or if there is such a thing as "inactive" while the greens still there?

I'll try the easy picking/soak/brush as since there's some past damage anyway, this may be a good learning experience. I'll take it slow!

Josh

[Akropolis]

Are you certain it is BD?
When you poke at it ligthly with a tooth pick, is a light green powdery substance produced?
PeteB

[SC]

The red was BD.  Or I guess it is more accurate to say that the red is BD but at a later and more stable stage.  However, there appears to be at least one light green spot of active BD on the obverse.  BD can also return to the more active light green phase around the edges of the red phase.

One option might be to get some of Bruce's mixtures, make up a small bit and put a drop on the light green spot(s).  Leaving it, as Bruce says for an hour at first.  And repeat as necessary.  A less aggressive option than a full soak. If that does not halt it then you can always do a more fulsome soak later.

I find the metallurgy of these coins interesting.  They are not properly silvered like the slightly later antoniniani (ie some Gallienus).  I am not sure if they were surfaced enhanced by the pickling method at this stage.  However, even contemporary issues clearly come in higher silver and lower silver versions.  Not sure if there was some "cheating" with lower silver versions being made, or if it is poor quality control, or if it is simply differences in how the alloy reacted post burial.

Shawn