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Author Topic: Cleaning story  (Read 3295 times)

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Offline Figleaf

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Re: Cleaning story
« Reply #30 on: November 13, 2016, 11:54:21 AM »
Meanwhile, here is an illustration of my most persistent chloride problem. These are brass coins of British West Africa. The smalles are hardly recognisable. I am told the red stuff is copper...

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline Figleaf

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Re: Cleaning story
« Reply #31 on: November 13, 2016, 12:08:40 PM »
And here is my second worst problem. The intense light of the scanner makes it look presentable, but in daylight, most of the lettering and design is unidentifiable, to the point where I can't tell which side is up. This used to be an unc aluminium coin of British West Africa. It is not zinc, so it can't be wet storage stain, but the white powder sure looked like it.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline bruce61813

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Re: Cleaning story
« Reply #32 on: November 13, 2016, 03:39:18 PM »
Meanwhile, here is an illustration of my most persistent chloride problem. These are brass coins of British West Africa. The smallest are hardly recognizable. I am told the red stuff is copper...
Peter
Peter, a quick bit of research came up with "Red Rot", it is apparently common in the music world among the brass instrument players. It is caused by acids attacking the zinc in the brass alloy. Initially it attacks the surface, so the underlying material is still sound, so if you have access to a mildly abrasive material, something made for polishing plastics, might work. Then a coating of REN wax to keep atmospheric acids away from them.

Bruce 

Offline bruce61813

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Re: Cleaning story
« Reply #33 on: November 13, 2016, 03:53:22 PM »
And here is my second worst problem. The intense light of the scanner makes it look presentable, but in daylight, most of the lettering and design is unidentifiable, to the point where I can't tell which side is up. This used to be an unc aluminium coin of British West Africa. It is not zinc, so it can't be wet storage stain, but the white powder sure looked like it.
Peter

Peter, you have really answered you own question. Here is a link to a very good article, but not "over your head" technical. http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=187
To boil things down, keep aluminum away from water. Again, a good coat of REN Wax should help, and maybe some sort of waterproof storage, even as simple as poly ziplock bags.

Bruce

Offline mrbadexample

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Re: Cleaning story
« Reply #34 on: November 13, 2016, 11:51:25 PM »
And here is my second worst problem. The intense light of the scanner makes it look presentable, but in daylight, most of the lettering and design is unidentifiable, to the point where I can't tell which side is up. This used to be an unc aluminium coin of British West Africa. It is not zinc, so it can't be wet storage stain, but the white powder sure looked like it.

Peter

Is that missing the D in EDWARD or is it just a result of the problem Peter?

Offline Figleaf

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Re: Cleaning story
« Reply #35 on: November 14, 2016, 07:37:02 PM »
Peter, a quick bit of research came up with "Red Rot", it is apparently common in the music world among the brass instrument players. It is caused by acids attacking the zinc in the brass alloy. Initially it attacks the surface, so the underlying material is still sound, so if you have access to a mildly abrasive material, something made for polishing plastics, might work. Then a coating of REN wax to keep atmospheric acids away from them.

Red rot is an appropriate name. My wife had a product in stock for spiffing up the brass pots and pans she doesn't have, so I used that. At least, I used the part I didn't spill on the bathroom floor ;D The good news is that it worked as advertised. I could take off all or practically all the red at the price of a blistered finger top. :) The bad news is that the coins now have an unnatural, pale yellow look. Since the coins were lost as they were, the net result was an enormous improvement, but it shifted the problem. Rather than seal off the coins, I have left them open to Paris air, hoping that they will eventually get a natural colour, but if there is anything to speed up the process, I am willing to try it.

A curious by-product of this experience was that the coins of George V were considerably more difficult to liberate from red-rot (I really like that name) than later coins. I suspect a different zinc content... Also, better grade coins cleaned more easily. A smoother surface, maybe?

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline Figleaf

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Re: Cleaning story
« Reply #36 on: November 14, 2016, 07:47:51 PM »
That alu coin is so covered with grey-grit I can't just leave it. Mrbadexample is right: there's no way to tell if the first D of EDWARD is missing or snowed under and I tried the USB microscope. At least, I have to get rid of the worst soggy-snow, so I can see the coin again without light tricks. It looks like an overused washer now. The alu is too soft for the glass-fiber brush. Any ideas, Bruce?

And no, the problem is not moisture. It's the same @#$% acid (HClO3?) that caused the red-rot (great tongue vibrations when pronounced the Scottish way), I suspect

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline bruce61813

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Re: Cleaning story
« Reply #37 on: November 14, 2016, 10:42:42 PM »
Try a paste made of baking soda and liquid soap. Use an old toothbrush, brush gently. That is about the best I can come up with that won't hurt the coin.

bruce

Offline Kopper Ken

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Re: Cleaning story
« Reply #38 on: November 15, 2016, 11:44:01 PM »
For the brass coins try putting them in contact with your body for a period of time.  You'll get a nice pleasing patina. :thumbsup:

KK

Offline Figleaf

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Re: Cleaning story
« Reply #39 on: November 16, 2016, 12:42:39 AM »
Me? The coins? Or both? ;)

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline Kopper Ken

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Re: Cleaning story
« Reply #40 on: November 26, 2016, 04:58:13 AM »
Sorry...definitely meant the coins.  You definitely have a pleasing patina (humor) already!!!

KK :perfect:

Offline Figleaf

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Re: Cleaning story
« Reply #41 on: December 16, 2016, 12:10:43 AM »
Here's yet another instalment of my story. A silver coin that looked like it was handled by Trump's makeup artist. ;) I dipped it and it now looks again like it did when it was taken out of a Franklin mint unc set.

Two points. First, the label on the dip says to use it for 15 minutes. The nearer a coin is to unc, the less time you need to keep it in the dip sauce. For a vf coin, 30 seconds is enough, but this one took only ten seconds. Second point: the pictures show how wrong it is the proclaim you should never clean a coin. Furthermore, the story shows how the revulsion for and fear of silver dip is overdone.

(Either my screen will be repaired tomorrow or I will be told that my 'puter is dying. Therefore I didn't do any colour adjustment. The pics look horribly blue on my screen.)

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline bruce61813

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Re: Cleaning story
« Reply #42 on: December 16, 2016, 09:30:04 PM »
But leave it to sun and open air and it will tone down after awhile.  ;D

Bruce

Offline Sgard

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Re: Cleaning story
« Reply #43 on: January 05, 2017, 11:32:27 AM »
Iron Oxide from German kopek coins ( WW1 ), can to clean with Palmolive liquid soap. Put coin in soap and wait some days. Rust dissolve. Colorless soap will remain colour to greenish blue. Coin will be in iron colour.

Attention! You must to control process twice a day and wash coin under water. If oxide fields are deep, you can to damage coin.

Offline Figleaf

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Re: Cleaning story
« Reply #44 on: January 06, 2017, 09:11:34 PM »
Those coins are no longer with me, Sgard, but I'll keep that in mind for any future iron disasters.

Meanwhile, here's my current complication. Treating red rot on brass with my wife's brass pots 'n pans "shampoo" worked wonderfully. The first treated corroded coins are already starting to regain their natural beautiful brass shine. Then, I came across this awesome foursome, all pretty Peruvians. The very same treatment did not work well on the largest. Some muck came off, but probably as a consequence of restless rubbing only. The sediment is orange, rather than red, with some baby blue mixed in, so, for lack of a nice alliterating name, I have settled for "Trump treacle". They will be Trump toast if I can't find a smart solution for their sorry state.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.