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FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Coin Photography, Conservation and Storage  |  Topic: Another BD effort 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: Another BD effort  (Read 2436 times)
slokind
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« on: October 22, 2008, 09:32:08 pm »

In another category (on the Financial Crisis) I said that for want of new coins to photograph, I went and got some that remained unfiled, though flipped.
I knew I had the IOVI CONSERVATORI / VICTORIA AVG of Antioch to go with the GENIO ANTIOCHENI / APOLLINI SANCTO, and here it was, but alas it has BD, and perhaps quite badly.
As with my Commodus Alexandria Troas eagle, I'll post its shocking state first now and start to work on it tomorrow, with the DW and toothbrush.
I'm glad the others are merely unidentified!
Pat L.
click and zoom to see better
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moonmoth
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« Reply #1 on: October 23, 2008, 12:21:44 am »

That does look like a bad infection, the poor thing.

We are told that BD can spread to other coins. If this was in a box with others, they will all need a close examination. Also, your photographic stage will need a thorough clean.

I say "we are told" because cross-infection hasn't happened to me.   I wonder if anyone has first-hand experience of this?

Bill
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slokind
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« Reply #2 on: October 23, 2008, 12:30:34 am »

Well, I SHALL watch; the Apollo and the Zeus came in a single small flip with the stiff paper between them; they will no longer share a flip.  So far, the Apollo is well.  I SHALL clean my stage, easily, since it is glass.  I fancy that in case of damp, or perhaps extraneous salts (as in sweat?), BD might be contagious.  Mercifully, it hasn't happened to me, but, like you, I don't know that it's impossible (though metal and apples are not much alike, no harm in being clean).
Pat
Here is the Apollo I bought together with the Zeus.  As you see, it is sound.  The best one I know is Doug Smith's, which is in my Numiswiki article on colored statuary.  The Apollo, like the Serapis of Alexandria, was ascribed to Bryaxis in ancient sources; see that article http://www.forumancientcoins.com/numiswiki/view.asp?key=Colored%20Statues .  My Apollo is Officna 9 (with the delta and epsilon).  It weighs 1.64g and is 15mm.  See Failmezger's pl. 13, no. 229 (the photos are by Doug Smith).
My Jove, by the way, also 15mm, weighs only 1.24g.  Bronzes so small are ticky work to treat.
click image to zoom
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areich
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« Reply #3 on: October 23, 2008, 01:30:46 am »

The problem is that the very first stage of BD is often not visible in hand but will show
clearly in a photo. I've had a few coins with nice, closed and original patinas that looked perfectly fine
in hand but a photo showed some very superficial BD, but clearly BD from the color. Knowing it was there it could
be seen under magnification. This could not have come from another coin and wasn't there when I first got the coin.
I just wiped it off but maybe I'll have to look again at the one specific coin I remember.
It still looks absolutely fine in hand.

Andreas
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moonmoth
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« Reply #4 on: October 23, 2008, 01:56:00 am »

Andreas, if you saw bd on the surface, there's a very good chance that it is deep inside the coin too.  If I were you, I would not delay re-checking that coin, and even if the surfaces look sound it might be worth giving it the sodium sesquicarbonate treatment.

Pat's Tyche/Apollo looks fine, as you say, Pat.  Nice coin.  My example is a little more worn, officina 8, and has SNA isntead of SMA in the exergue, oddly.

Bill
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slokind
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« Reply #5 on: October 24, 2008, 11:56:24 pm »

In medias res.  After two DW soaks and one session in Gringotts #1 (it sizzled when I dropped it in, and I was surprised to see it whole).  It is still wet, but I took its picture (now I'll go and make another mild batch of Gringott's to try to eliminate the remaining red spots.  You see, two soaks in DW turned predictably bright rust red, all over, both sides!  Most of this came off on the old toothbrush and my fingers when I took it out for 'washing under running water'.
Whether it survives, we shall see, but it had to be done.  What is lost already was lost.
It's Officina 4,  Greek_Delta
Pat L.
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moonmoth
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« Reply #6 on: October 26, 2008, 05:59:18 am »

The description of the uses of #1 reads like sodium sesquicarbonate.   #3 reads like a strong base, could be TSP; I have tried NaOH with similar results.  #2 might be a weaker base or detergent mix.

I wonder if JK Rowling will notice those names sometime?

Bill
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slokind
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« Reply #7 on: October 26, 2008, 12:47:00 pm »

You mean that name comes from Harry Potter?
Anyhow, here is my final product.  The little Antioch Pagan Zeus has lost 0.02g already and hasn't much to lose.  Anyway, now the epsilon as well as the delta is plain, so it's the same officina as my Apollo (above).
Pat L.
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moonmoth
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« Reply #8 on: October 26, 2008, 03:57:01 pm »

With one G, it's the name of the wizard's bank in the Potter books.

There are a few light coloured spots there, but also the typical red areas, so those spots must be safe.  The red colour should tone down a bit over the next few days - though I don't know if it will if it is sealed off from the air. Or it might be possible to brush some of it off, though you might not think that desirable.

Bill
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« Reply #9 on: November 01, 2008, 09:31:27 am »

the name does indeed come from the HP book. About 6 years ago, when the formula was worked out, Kevin Sandes [Mayadigger] asked to try some of the 'magic' coin cleaner, as it does work very well on most clay forms, and the name was born.

It is a homemade sodium sesquicarbonate, as the lab grade is harder to obtain, and who need 50 pounds. The formula for the most part has been published here for several years, so no big secret, but again, most people don't want to deal with 5 pounds of materials for a limited purpose.

BD is spread by the dust, but it also needs humidity. This has been seen by me, and is also noted in the paper from the University of Texas, so it is not a limited observation. Most coins require a brushing after cleaning of any kind, I prefer a battery powered dremel with a brass brush. It removes remaining surface oxides and in effect polishes the surface without grinding to bare metal. Many coins have a fair percentage of iron in the alloys, there is a link to an Italian paper buried in Forums archives that has a study of the metallurgy of a series of coins, that would account for the rust.http://www.uniroma2.it/eventi/monete/nocpan.html , this was originally posted by Rugser many years ago.

Bruce
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