Author Topic: Cleaning Silver coins with Brasso  (Read 15998 times)

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Offline Coinsforever

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Re: Cleaning Silver coins with Brasso
« Reply #15 on: October 13, 2012, 02:33:43 PM »
I have never tried heating a coin to any temperature either by putting directly over flame or through induction heating. Sudden heating & sudden cooling convert  the metal into brittle and chances of damage is quite high . (Quenching ).

In industry normally all metals alloys after quenching /hardening goes for tempering (Tempering consists of heating the steel to a specific temperature (below its hardening temperature), holding it at that temperature for the required length of time, and then cooling it, usually instill air)

Paint remover , thinner or else are dangerous and deteriorate   the coin surface severely.

I prefer to keep the coins in original/natural  state , if rust appears on few of  the coins I quarantine such stuffs separately to avoid risk of getting contamination to other fine stuff.


Cheers ;D
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Offline asm

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Re: Cleaning Silver coins with Brasso
« Reply #16 on: October 13, 2012, 02:55:25 PM »
I have used various methods but never Silvo or Brasso. They require a lot of rubbing and leave the chemicals on the coin..........As regards heating, I have never tried it till now.

Amit
"It Is Better To Light A Candle Than To Curse The Darkness"

Offline cmerc

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Re: Cleaning Silver coins with Brasso
« Reply #17 on: October 18, 2012, 10:06:48 PM »
I used brasso to clean coins when I started collecting 14 years ago.  The coins looked nice and shiny then.  Over time, a strange patina develops and the coin appears clearly cleaned.  Bad idea, damaged some nice coins this way-lots of visible hairline scratches.  NO BRASSO.

I also tried using vinegar (acetic acid) to remove tarnish from silver coins.  It does a decent job, most of the black patina seems to go away, but the coin loses its appeal.  There will always be black patches where the staining/toning is stubborn and they will look ugly.  Again, not a good idea.  NO VINEGAR. 

With my coins, i just rinse them in acetone for ~15-30 secs, or leave them soaked for a few mins at most.  It takes care of most of the oils on the coins.  If the coin is XF or below, and there is paint, green residue, etc., I wet the affected areas with acetone and lightly touch with my fingers to see if it comes off.  If not, I leave it alone and try to upgrade it with a better condition coin. 
Defending this hobby against a disapproving family since 1998.

Offline bruce61813

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Re: Cleaning Silver coins with Brasso
« Reply #18 on: November 07, 2012, 02:57:36 AM »
Brasso is a no-no, as in several of the threads, it is abrasive. For silver there are some high quality silver cleaners, that are not abrasive. they tend to leave the surface a bit dull. this can corrected by rubbing with a soft cotton cloth . The black silver oxide should also be removed. If it is grease/finger oils ordinary alcohol soak followed by a soft cloth rub should take it out. Heat is not good, as with the knife blade, at its annealing temperature, silver will blue and it goes through the metal and is permanent. 

On solid silver, 6 vdc low current electrolysis does work to remove thick oxide . But  [the big oh by the way] never do this with plated items, the thick black oxide is the surface silver, remove it and the surface silver is gone. There  are times when it is a choice, see the attached photo. This was a black lump of oxide, very little detail, so i went for some detail.

Bruce

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Re: Cleaning Silver coins with Brasso
« Reply #19 on: November 07, 2012, 10:24:08 AM »
Choice medal, Bruce. Glad it met you.

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 Silver coins with Brasso
« Reply #20 on: November 07, 2012, 03:14:12 PM »
So am I. But back to the point, as you can see, the sliver on the back has been stripped. When I received the medallion the back look blank, but i decided to remove some of the oxide, and the  back went from blank to readable. I removed the minimum to be able to read and see what was there. Call it a cautionary tale about preservation.

bruce

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Re: Cleaning Silver coins with Brasso
« Reply #21 on: November 07, 2012, 04:16:08 PM »
Since most of the damage was on one side, I suspect the medal was stored in an inappropriate way for many years.

Great job to restore its readability. Since the details are still loud and clear, I suppose it's just a case of a missing top layer that may have been applied after the medal was struck in the first place. If this medal would have been treated with an abrasive instead, more than the top layer would have been lost. It would have attacked the detail.

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 Silver coins with Brasso
« Reply #22 on: March 31, 2013, 05:37:17 AM »
I agree about the poor storage. I suspect that the black is silver sulphide mixed with some other silver oxide. So, I intend to leave it. The silver plate is mostly gone from the reverse. I could work on it, but best left as is.

Bruce