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FORVM`s Classical Numismatics Discussion Board  |  Numismatic and History Discussions  |  Uncleaned Ancient Coin Discussion (Moderator: bruce61813)  |  Topic: Cleaning Catastrophe seeking (a) Sympathy (b) What went wrong 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: Cleaning Catastrophe seeking (a) Sympathy (b) What went wrong  (Read 3613 times)
Andrew McCabe
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« on: April 03, 2011, 12:34:03 pm »

Over 30 years of collecting I have never deliberately cleaned any coin I owned, apart from an occasional gentle wash in soapy water to remove loose dirt.

About a year ago I bought an uncleaned lot of Roman Republican bronzes, and over a couple of months repeatedly soaked them in distilled water and applied a soft toothbrush with vigour on a daily basis. The end result was  ... nothing at all. The lot looks just as encrusted today as it did when I bought them. Perhaps they changed imperceptibly, but from a collector's view they still look like encrusted lumps.

The unfortunate learning point from this initial essay into cleaning is that I probably needed to bring out some chemicals to have any effect. Therein lay the seeds to disaster. And unfortunately it did not relate to the low value batch of uncleaned's I might have taken risks with.

I recently bought a smashing adorable Octavian / Julius Caesar bronze dupondius with a lovely chocolate brown patina, in near EF, marred only by a patinated corrosion patch on both sides and by some spots of bronze disease. I was content enough with the patinated corrosion patch as-was, but before putting the coin into storage I wished to rid it of the bronze disease.

So, I spent several evenings reading tips on this list. I concluded that a short dip in some baking soda solution with a little washing soda added was the way to go.

I took your advice (thank you all). I respected the wisdom of the uncleaned coin experts on Forum to such an extent that I reckoned the distilled advice from having cleaned thousands of coins would serve me right. Indeed I'd seen photographs of positive results posted by many of you (thank you again!). I read the caveats, procedures, warnings and advice with all seriousness. And proceeded the prepare a solution of distilled water with some baking soda and a little washing soda added. I dipped the coin for some 15 minutes, took it out, washed it, and ... the results are below.

A $1000 coin now looks like a piece of junk. Thanks again!

I do not intend to clean any coin of mine ever again. Ever. No matter how it looks. No doubt someone will explain to me what went wrong, or what was wrong with the coin to start with. No doubt an inability to follow advice properly. Still no coin of mine will ever be touched with anything wet or chemical so long as I still like coins. Never ever ever again.
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Rich Beale
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« Reply #1 on: April 03, 2011, 01:16:01 pm »

Hi Andrew, my condolences..

Ah, bronze disease... I have tried a few techniques myself.. distilled water, mechanical removal, even Gringotts.. I have come to the conclusion that the oldest solution remains the best. Bake until the moisture is completely gone, then seal the surface to prevent recurrence.

In any case, I think your coin remains definitely salvageable. The de-patinated areas of corrosion can be re-patinated to something approximating the earlier appearance. If you wanted to send the coin to me (and trust me not to ruin it further!) I could probably do it for you.
 
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Jay GT4
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« Reply #2 on: April 03, 2011, 01:17:12 pm »

Andrew with all due respect I can't see how distilled water and baking soda would do that to a coin.  I think what happened is that more of the coin than you thought was re-patinated.  The DW and Baking soda probably removed the fake patina and what you are seeing is what the coin really looked like.  It's not all lost.  I would treat the BD and then use another patination product and wax.  I know it's not what we want to do, but in this case it will remove the BD and give the coin a more pleasing appearance.
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« Reply #3 on: April 03, 2011, 01:26:24 pm »

Andrew with all due respect I can't see how distilled water and baking soda would do that to a coin.  I think what happened is that more of the coin than you thought was re-patinated.  The DW and Baking soda probably removed the fake patina and what you are seeing is what the coin really looked like.  It's not all lost.  I would treat the BD and then use another patination product and wax.  I know it's not what we want to do, but in this case it will remove the BD and give the coin a more pleasing appearance.

Thanks for the thoughts. Distilled water, baking soda and washing soda was what I used. I just don't know. Maybe the coin had been painted with an artificial patina before I bought it. Dreadful. You are probably right.

Wax? My aim now is to make the coin look a little less bad with the lowest risk. What exactly would you propose? What wax?
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Andrew McCabe
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« Reply #4 on: April 03, 2011, 01:29:38 pm »

Hi Andrew, my condolences..

Ah, bronze disease... I have tried a few techniques myself.. distilled water, mechanical removal, even Gringotts.. I have come to the conclusion that the oldest solution remains the best. Bake until the moisture is completely gone, then seal the surface to prevent recurrence.

In any case, I think your coin remains definitely salvageable. The de-patinated areas of corrosion can be re-patinated to something approximating the earlier appearance. If you wanted to send the coin to me (and trust me not to ruin it further!) I could probably do it for you.
 

Rich

That's a very kind offer and I'll take you up on it once I next have the coin in hand (it's in storage). I don't mind risking it further in an attempt to salvage any remotely better looking appearance.

Andrew
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Jay GT4
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« Reply #5 on: April 03, 2011, 01:37:38 pm »

I use Renwax after I treat a BD coin.  Make sure the BD is properly treated and no traces remain.  Then make sure it is completely dry as Rich mentioned and then apply very thin layers of Renwax.  I usually just take a very small amount on my index finger and then gently rub it in.  It seals the coin and somewhat deepens the appearance.  It doesn't look as "dry" after a BD treatment and it helps seal the coin from humidity.  I would take Rich up on his offer.

It's still a beautiful coin BTW!
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« Reply #6 on: April 03, 2011, 02:02:18 pm »

I use Renwax after I treat a BD coin.  Make sure the BD is properly treated and no traces remain.  Then make sure it is completely dry as Rich mentioned and then apply very thin layers of Renwax.  I usually just take a very small amount on my index finger and then gently rub it in.  It seals the coin and somewhat deepens the appearance.  It doesn't look as "dry" after a BD treatment and it helps seal the coin from humidity.  I would take Rich up on his offer.

It's still a beautiful coin BTW!

Thanks Jay

You said:
"Make sure the BD is properly treated and no traces remain. "

That of course is where the catastrophe started, exactly what I was attempting for the first time in my life!

It sounds so easy. Just like Julia Child saying "make up some Hollandaise and a port-wine reduction whilst you lightly poach the fish in a bain-marie, and prepare the crown of lamb in the usual manner".

Andrew
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Jay GT4
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« Reply #7 on: April 03, 2011, 02:14:12 pm »

 Grin  You're right, it sounds so easy but in reality it takes a lot of guts and patience to get rid of BD.  The good news is that if you didn't try this and just put it away in a safe or coin cabinet the BD would just continue to get worse and eventually the coin would be completely ruined.  I boil my coins in the DW and gringott's or baking soda and then brush, then repeat as many times as necessary until there is no trace of the green powder.

A few of my coins had been re-patinated by previous owners.  Some are done so good you'd never know unless boiled, others are blatantly obvious.   Again, this is a good thing you caught it now.  Too bad the seller didn't disclose it, if he knew at all...
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« Reply #8 on: April 03, 2011, 05:13:02 pm »

I have used a little Kiwi shoe polish  to seal out moisture after treating  a coin for BD. Except that I use a silver nitrate wet treatment, drying the coin with heat and a little wax rubbed in with a finger seems to do the trick. Almost any color is fine. There is so little pigment in the wax that it won't affect the color.

Regards, Dave
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« Reply #9 on: April 03, 2011, 06:16:08 pm »

That is a fine offer by Rich.

I really does seem that a previous owner has done a little skillful hiding of things.
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« Reply #10 on: April 03, 2011, 07:20:12 pm »

When I initially read te first post and looked at the pictures my very first though was that it appears that this coin probably had BD in the past and was treated and an artificial patina added. The brown patina in that photo looks a lot like some of the patinas I have seen when that jax stuff, or whatever it is called, is used.

I then read the rest of the posts and it looks like everyone is in agreement. I wouldn't be harsh on yourself Andrew. You used a safe and effective method, and it just so happens discovered some skillful touch up while at it...

I think the goal is to make sure you stop the BD in it's tracks this time, hopefully, repatina the coin, and seal it appropriately. If you don't want to seal it, just watch it and if I were you, I would pack a bunch of dessicant, etc nearby to try to keep as much moisture away from it as possible.

I think that no matter how you went about saving this coin, or who did the saving, the results would have been the same. My understanding is that a lot of those repatination product wipe off easily, especially if the coin isn't sealed afterwards.

I hope all goes well and keep us updated on the crisis.

PS- please excuse typos. I am on an iPhone.... Enough said.
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« Reply #11 on: April 03, 2011, 08:50:42 pm »

a) sympathy given. Its always a little stunning to do a gentle attempt at getting rid of a little BD and finding...that. It looks like some Jax/Dellers etc were used like makeup.
I've had mixed success ridding a coin forever of reappearing BD. I'd consider this one very much a problem child - good to hear Rich has thrown his name in to save Octavian!
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« Reply #12 on: April 03, 2011, 09:43:13 pm »

Just a thought about what might have gone wrong since you were treating the coin very carefully. There is a fair amount of acidity associated with BD. When you soaked the coin in bicarbonate this could have reacted to create carbon dioxide gas bubbles. Since the coin was coated with some kind of non-porous material it seems likely that this loosened the artificial patina and caused it to pop off.

Regards, Dave
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« Reply #13 on: April 03, 2011, 11:24:11 pm »

I'm not much good at cleaning coins, but I've had excellent luck in the past arresting fresh BD spots by baking the coin.  A couple with bad BD were fixed by Gringott's mix.

The exposed corrosion core area of the coin looks very unusual; almost like plaster or the like.  Is it a trick of the light?

Truth be told, I'm usually scared off by BD, before purchase.  I hope everything works out.
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« Reply #14 on: April 04, 2011, 04:22:28 am »

I'm not much good at cleaning coins, but I've had excellent luck in the past arresting fresh BD spots by baking the coin.  A couple with bad BD were fixed by Gringott's mix.

The exposed corrosion core area of the coin looks very unusual; almost like plaster or the like.  Is it a trick of the light?

Truth be told, I'm usually scared off by BD, before purchase.  I hope everything works out.

The exposed corrosion area looks like what it looks - copper, totally eaten away. The coin as purchased  looked relatively fine, a couple of tiny spots of possibly old and stabilised BD. When I received it I realised I needed to do something. Hence I converted it from the top to the bottom picture!
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« Reply #15 on: April 04, 2011, 08:59:40 am »

The exposed corrosion core area of the coin looks very unusual; almost like plaster or the like.  Is it a trick of the light?


The whitish plaster-like material would be Copper(I)chloride. This is what  defines "bronze disease", not green spots on the surface which can arise from various things. I have no experience in conserving such valuable coins. Just drying it out and painting it over may be the simplest and best path but eventually the problem could resurface.

Regards, Dave
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« Reply #16 on: April 04, 2011, 10:11:24 am »

Ah, ok, I was referring to the green spots when I mentioned baking.

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« Reply #17 on: April 07, 2011, 03:40:41 am »

Andrew,

You do have my sympathies.

On a more positive note while the coin currently looks ugly as hell it does not appear to be any worse off structurally (at least as a result of your efforts), just aesthetically.  Think of it as a work in progress.  Wandering into the middle of a DIY project never looks good.

You have lost a chocolaty patina - but one that was very likely applied, assisted etc. and not natural toning.  You have also "gained" an ugly colouring to all the areas that already/previously showed signs of serious pitting from BD.

On a cheap coin I would proceed as normal for BD.  Manually remove all the newly exposed green and white stuff through brushing (soft toothbrush, harder toothbrush than soft (really soft) brass brush, and then picking away the green stuff from the deeper holes.  Then more GG soak and bake dry.  However, I would also be prepared for the fact that there was a chance (hard to evaluate without coin in hand and under microscope) that the entire core of the coin was so toasted by BD that it would not survive and would just reveal more and more until it lost structural integrity totally in the cleaning attempts (ie crumbled).

Obviously your coin is not/not cheap and you do not want to proceed in this way!!

But on the other hand you can't just coat or wax or repatinate it and forget it.  It is in such an ugly state because it still has BD.  You could have it looking like your original but even better - ie no green BD spots - if you wished by wiping as much white off then re-patinating it with a dye product then sealing with Ren wax.  It would look great.  But it would still have BD and that would chew through it and one day it would totally crumble.

I got a nice VF/gF Claudian as that was like this.  Showed some BD on back which I thought could clean out quickly.  Then I discovered that almost the entire back had active BD.  It had been dyed and waxed and what I was seeing was simply the most aggressive and advanced BD spots poking through the dye and wax.  When I stripped the dye and wax off in soaks the back looked like a pizza that had been left on the sidewalk for a week.   As I cleaned it I watched the back go from gF to F to aF to aVG etc.  It is still not BD free to this day.  But at least I know I have arrested the worst of the BD and will have it stable one day.  I was also not angry as I had got it for a song from a very honest dealer who knew it had BD and realized it might be in a bad way.

So what are you to do?

I would suggest:

1) Keep it safe and dry (not sealed in plastic and preferably with silica bags nearby) and wait for more advice.  I think it definitely needs to have more conservation treatement before any final preservation or aesthetic treatment.  I just hope someone can suggest something gentler than what I outlined for a cheaper coin above.  But there may not be any magic bullet.

2) Have a word with your dealer.  Hard to tell how much "caveat emptor" plays here.  Your coin may have looked ok but it clearly was sick on the inside.    I assume that the price you paid took into account the way the coin looked - ie it was pitted - but was likely based on the assumption that was structurally sound.  That was clearly not the case.  Who knew what when?  Someone has clearly treated it before for BD.  Maybe they thought it was cured and tried to "pretty it up".  Maybe they knew it still had BD and tried to hide it.  In any event it is important that you point out that you did not ruin or worsen the coin, you took action against BD that revealed the true sorry state of the coin.

Shawn

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« Reply #18 on: April 07, 2011, 04:00:41 am »

......
I would suggest:

1) Keep it safe and dry (not sealed in plastic and preferably with silica bags nearby) and wait for more advice.  I think it definitely needs to have more conservation treatement before any final preservation or aesthetic treatment.  I just hope someone can suggest something gentler than what I outlined for a cheaper coin above.  But there may not be any magic bullet.

2) Have a word with your dealer.  Hard to tell how much "caveat emptor" plays here.  Your coin may have looked ok but it clearly was sick on the inside.    I assume that the price you paid took into account the way the coin looked - ie it was pitted - but was likely based on the assumption that was structurally sound.  That was clearly not the case.  Who knew what when?  Someone has clearly treated it before for BD.  Maybe they thought it was cured and tried to "pretty it up".  Maybe they knew it still had BD and tried to hide it.  In any event it is important that you point out that you did not ruin or worsen the coin, you took action against BD that revealed the true sorry state of the coin.

Shawn

Shawn

You have raised a number of good points. Indeed the conclusion was dawning on me that my coin is probably not really any worse than it started - the loss of filling material seems to be exclusively limited to areas which were already corroded below the surface of the field, so there probably is no new net metal loss. The coin is currently inside an acid-free paper envelope which I guess is as good a place as any for the moment. As discussed earlier in the thread I'll bring it to Rich Beale and I guess discuss with him what might or might not be done. Preserving the coin from further damage is obviously key, but an aesthetic result is in the end also important given that the coin has one of the most magnificent portraits of Julius Caesar known to mankind. Incidentally Toynbee in Roman Historical Portraits comments on the type as one of his best numismatic portraits, realistic rather tha idealised but with the ugly features toned down.

Regarding dealer - difficult call as it was bought at public auction, with the corrosion commented on in its description, and some BD evident in the auction photo. I would perhaps have had reason to return it as having uncontrolled BD, but now having stripped it, it's a difficult case - the auction house could say "of course it was repatinated but you've now removed the pretty patina". I'm an experienced coin buyer so this, to me, falls under caveat emptor, in that I knowingly bought a coin with potential corrosion problems. So I'll live with it, and hope I can stop its degradation.
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« Reply #19 on: April 17, 2011, 09:07:33 am »

Just wondering status. I am looking forward to seeing the "fixed" coin.

Chris
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« Reply #20 on: April 17, 2011, 09:15:43 am »

Just wondering status. I am looking forward to seeing the "fixed" coin.

Chris

Nothing as yet - my coin is located in a different city from my usual residence, so there's a logistics issue. Could be a month or two. I'll be sure to update you all when its condition changes - for better or worse!
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« Reply #21 on: May 20, 2011, 10:45:56 am »

I'll clean almost anything but I'm certain I would not touch something that costs or is valued at one strong

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