Silver sickness

Questions on polishing, restoration, conservation + manufacturing techniques

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kerangoumar
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Silver sickness

Postby kerangoumar » Wed Aug 08, 2007 1:01 am

Notwithstanding the presence on the web of endless logorrheic epics about werewolves with the disease, I would like to know how silver sickness in handled by forum members. Google the term. You'll laugh yourselves silly reading the pages cited - but nothing on treatment of the actual problem.
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kozy845
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Postby kozy845 » Tue Mar 11, 2008 12:26 pm

I'm bumping this up as I too would be very interested to know if anybody out there has anything to say about how to deal with this issue.
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kerangoumar
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Postby kerangoumar » Wed Mar 12, 2008 4:29 pm

the only thing i can think of at the moment is to call a doctor. lol. seriously, i would like some input from a metallurgist, if possible.
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admin
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Postby admin » Wed Mar 12, 2008 4:49 pm

Holly,
I've had the silver sickness for a couple of decades now, seems to get worse with each passing year and I've been told that once contracted it is incurable...or were you referring to the little black pitted marks one sees in the interiors of antique salts?

Regards, Tom
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kerangoumar
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Postby kerangoumar » Wed Mar 12, 2008 11:41 pm

yes silver sickness, the agglomerations of black somewhat sticky-seeming but unyielding goop on some silver. i have seen it on both sterling and plated items, on insides (mostly) and outsides.
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Doos
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Postby Doos » Thu Mar 13, 2008 5:53 am

Hi,

If I remember correct they are oxidations. Cupric gives black spots and cuprous gives red spots (or the other way round).
There are a few ways to get rid of them, the first is obviously repolishing with course paste and later with a fine one. Or you could boil/heat it a few times in a pickle/torch to create a pure silver (white) surface and then repolish with a fine paste. The latter is the best method as you don't know how deep some of the oxidations are.

There can also be blackening due to sulphur which form silversulphate and darkens when in contact with air/oxygen. You will have to polish that of and spray it with a protection coating. But that is an ugly solution.
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kerangoumar
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Postby kerangoumar » Thu Mar 13, 2008 2:23 pm

hello doos -

these offending scales don't come off with the usual pastes. i have experimented on some cheap used silverplated items and can tell you that scraping the scale off is not workable either, which leaves boiling or heating it in something like oxalic acid or another acid, as you suggested. maybe that is acceptable on non-antiques, heavy/thick gauge silver or unimportant items, but what of the fine chain, the 1800s bowl, etc etc. and i don't know where i could do this without blowing up the house.

the more usual sulphates are very annoying but - in the main - come off with a bit of spit and polish. doos, i don't think you would spray any protective coating, i certainly wouldn't. but i have found that the cocoa butter soap (my post
viewtopic.php?t=8599&highlight=cocoa+butter+soap) acts as a thin film protecting against oxidation which has not caused any adverse reaction in pieces that were treated this way 16 or more years ago - and they still have not tarnished.

a distant acquaintance of mine has an antique shop of dubious repute - her treatment is simple: put the piece on a lathe and scrub off the offending layer with steel wool or some more aggressive abrasive! she occasionally "helps out" the charity shop next door, which irritates the pickers no end when they find what might have been a pleasant plated piece and it's been ruined.
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Doos
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Postby Doos » Sat Mar 15, 2008 7:15 am

Hi,

It is indeed a nasty method.
When I did my apprentiship, my boss got a whole batch of antique silver that had been stored in a vault for over 30 years and it was to be auctioned at Christie's. All was black all over. The auctioneer made the choice to have it repolished by us and my boss indeed used some acid with a current running through it (forgot what it was - 20 years ago). We then hand polished it for shine - a 3 day job with 4 people working on it. Of course there was no such thing as a lovely patina to be found on them anymore, but it was better than leaving it jet black.

Nice trick with the butter, tastes better aswell I'm sure.
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kerangoumar
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Postby kerangoumar » Sat Mar 15, 2008 5:28 pm

well, doos, i would have bought them, black as toby's aspidistra, tho i wouldn't have when they were tarted up to look like the nice bright shiny silver everyone wants.

i have come to really like the "oil slick" iridescence one finnds in some heavily oxidied silver, the purplish blues etc. but silver sickness is something else, it ruins one's appreciation. luckily none of my important silver has this problem and that has just mad eme wonder:

anyone who is reading this, how old is the oldest piece you have with silver sickness?

i am wondering if it has something to do with the alloy composition - and is it possible that some silver is not properly blended after being mixed with the copper etc?

it just struck me that none of the really old pieces i have got have this problem.
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Postby SilverSurfer » Wed Jul 16, 2008 11:16 pm

anyone who is reading this, how old is the oldest piece you have with silver sickness?

it just struck me that none of the really old pieces i have got have this problem.


When I'm faced with a heavily tarnished piece, I usually try Tarn-X (thiourea in sulfamic acid) first, which will reduce silver sulfide to elemental silver. If the black coating is fairly thick, I'll wash it first with hot detergent to make sure that there are no embedded waxes or oils to repel the solution. When this works, thick sulfides are reduced to a whitish chalk-like coating, which I then polish away using Wright's Silver Polish. My feeling is that this takes off somewhat less silver than just using polish alone.

Thicker tarnish usually takes more Tarn-X applications, but there is great variability in susceptibility, unrelated to thickness. Some stains bleach out quickly, others take forever, or just don't yield. The worst case was a c.1870 Vanderslice & Co. coin silver (.900 fine) goblet that appeared to have been in a fire (perhaps "the" fire). Most of the outside surface was a dull coal black, almost like a flat paint, though I made sure it was indeed not an applied coating. Tarn-X had no effect whatsoever, nor did the silver polish. I finally had to go to 600 wet and dry sandpaper, the one and only time (thankfully) I've ever had to get this aggressive. I'm somewhat embarrassed to admit it here, but whatever that oxide/sulfide/??? was, it was like granite.

The next most aggravating piece was a Charles Hougham 1787 London helmet style creamer. It finally yielded to the Tarn-X, but only after repeated applications and rubbing over a couple of hours. But generally, according to my fuzzy anecdotal memory, I seem to recall that I generally have less problem with French (.950) and Brit (.925) pieces, and more trouble with American coin (nominally .900) and Continental silver (.800/.830/.835). So I think there may be some positive correlation to copper content, such as there is with silver scale formation, but this is just a guesstimate.

SS
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historydetective
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Postby historydetective » Sun Jun 20, 2010 8:17 am

Kerangoumar, what brand of cocoa butter butter soap are you using? I ask because there is a bewildering variety of formulations available, with some additionally containing shea butter, aloe, vitamin E, etc.

I am having heartbreaking problems with silver disease; for anyone who is confused about what it is, my pieces have black spots that are either a multitude of small, circular dots, or sometimes, a bigger, flat black spot in the shape of a drop of water. Polishing with Wrights isn't a good solution for me, as doing so takes tremendous effort to work and often leaves ugly pits. I'm going to try Tarn-X just on the spots (with a Q-tip), as Kerangoumar recommended. Is Tarn-X Glaze something that would work similarly to cocoa butter soap? Is it more gentle for fine silver than the regular Tarn-X, which many consider too harsh for silver, in general.

I have the notion that my problem appeared about 2 months after renovation work on my home, with the renovation having produced a prodigious amount of sheetrock dust. I've read that sheetrock contains metal ion chelators and calcium sulfate hydrate (I assume as dessicants). It's also interesting to note that Florida homeowners who are living the nightmare of toxic Chinese drywall first noticed something awry because of the dramatic tarnishing effect it had on their silver (I found an article mentioning that specifically).

About one-third of the pieces I buy in online auctions have this problem to some degree, and I think some high-volume sellers are thusly purging their collections of problematic pieces. But, I know that something about my home is harmful to some of my pieces, as they had a mirror finish when I got them, and now they have unsightly black spots, primarily in the interior of bowls. Being in a cabinet doesn't seem to help much, but my cabinet isn't completely airtight. And, by the way, I've noticed the opposite of some other posters, possibly by shear coincidence, but my American coin silver is faring well, and my American sterling is the most affected, except for 2 950 solid silver French plates, which were covered with black spots upon arrival, despite having been machine polished (ughh) by the seller.
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kerangoumar
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Re: Silver sickness

Postby kerangoumar » Sun Mar 06, 2016 1:02 pm

historydetective:

better late than never - so they say. i've been under some ferocious weather but now i am back. the cocoa butter soap - it was something i picked up at a german store - never found another cake - suposedly no one was buying. but there are cocoa butter soaps again and you could look in a store that sells "alternative" goods, whether "organic" or "delicatessen" type. don't let anyone sell you coconut soap which experience i have had several times over the years! be sure to look for one that is hard-milled or it will literally melt in your hands over a few weeks. somewhere i have a letter from theh Canadian Conservation Institute about cleaning silver/possibly silver sickness, i will try to dig it out.

kerangoumar
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Re: Silver sickness

Postby kerangoumar » Sun Mar 06, 2016 2:05 pm

Could not find the letter but essentially all the information from the Canadian Conservation Institute is here: http://canada.pch.gc.ca/eng/1439925170396

In my discussions with Lyndsie Selwyn silver sickness came up - it is thought that these spots begin as concentration of the alloy in the silver - someone didn't stir the pot enough, so to speak.

If you wonder what an anionic detergent is, it contains sodium dodecyl sulphate (sodium lauryl sulphate). Example: WA Paste, which is the same as Orvus, produced by Proctor & Gamble in the US.

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Re: Silver sickness

Postby dognose » Sun Mar 06, 2016 2:38 pm

Hi Kerangoumar,

Thanks for sharing the link to this useful document.

Trev.

kerangoumar
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Re: Silver sickness

Postby kerangoumar » Fri Mar 11, 2016 3:56 pm

Hi Trev -

Glad it is useful. It's funny - I told Lyndsie about my other silver cleaning method and nobody has an idea why it works. This is the one with cigar ashes - I suppose it won't be around much longer as smoking is being actively discouraged everywhere. (Don't actually know whether any ash will do - I've always just heard it in connection with cigs.)


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