How To Get Rid of Red Spots on Gold, Easy and Cheap

This has been published in a couple of places, but after seeing a gold 2014 Kennedy 50c Proof with such a spot on another board with all kinds of "suggestions" which were to generally just accept it or sell it, I showed a simple conserving procedure on my own. Also, many of you may have some gold with these annoying spots that can actually be dealt with pretty easily.

Before:
I then got a white microwaveable cereal bowl
Put 3 tablespoons of baking soda in some tap water (1/2 full bowl)
Microwaved on high for 2 1/2 minutes
Put in aluminum foil (I just put a piece about 4 x 5 inches)
Set coin on top of aluminum foil in the near boiling water
Let sit about 3 minutes.

After:



Sorry about the photo skills. But it was an excellent result for about 5 cents worth of materials, that were non-toxic. Nothing special, but it works and is easily done.

I showed this in the world section because I have some gold Libertads and Isle of Man gold that have similar spots. I need to dig them out on this Corona weekend and show results if people are interested.

 

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i just asked the question I have white spots and black ones

 

Metal foil and baking soda? The thoughts of those touching my coins gives me shivers.

But I'm curious - if this works, why is it working? What chemically is making the spot go away? Traditional knowledge holds that the red spot is a copper stain.

And will the spot stay away, or will it come back?

 

Yes, good point physics. I always liberally rinse.

 

I would be worried of scratching the surface.

 

These are "copper spots". Removing them is a no no. NGC/ PGGS will list that as "details" spot removal.

 

Actually this is an electrolytic reaction. No scratches or sharp edges.
This will DEFINITELY pass muster at NGC/PCGS. No trace of spot even under magnification. In fact they - the services - use a similar technique themselves.

I was trying to be helpful, why the negative nannies? It’s good applicable science.

 

If it will pass the scrutiny from TPGs/ you have definately got a winner for copper spot removal.
John

 

That is correct. It will not damage the metal at all, I think. I use the same procedure for cleaning my antique silver. Saves polishing and the risk of rubbing the oh-so-important hallmarks.

 

Is the spotted side sitting facing the foil or away?

And, if I were to send a spotty coin to NCS (or the PCGS service) is this the sort of thing done?

What level of fineness? .900 and better?

 

OK, it is very safe, but possibly not if you just leave a low fineness gold piece in there.

Anyway, here is one I just did 15 minutes ago:

Host coin is 1969 Anguilla Ten Dollars proof, fineness 0.900

Before:



After:



Couple pictures of "procedure":
First is after microwaving, bowl plus water plus Sodium Bicarbonate, aluminum foil piece THEN added
Second is with coin in, spot facing UP - I don't think that makes a difference

 

Stork, that would be a "yes" as far as their treatment, as far as I know.

 

@Insider , very curious as to your thoughts on this. Is this how NCS does it? (I understand if its "classified").

Any thoughts on the potential for harming coins with this method?

Also, calling the chemists: @desertgem @BadThad

 

He has said as much but in some thread gave hint to it....

I may try an Isle of Man later tonight or tomorrow because I hate my vikings being messed up.

 

Dilute nitric acid works the best.

 

If you think about it, oxidizing an oxidant may work but may not be the best move as it may eat underlying metal or alloyed constituents and alter the surface (that would exclude pure gold however).
There is nothing magic about this procedure, it really is just applied chemistry and as they say, it is "cheap as chips".

 

That is what I was worrying about. Not sure I would care on .9167 bullion, didn't think it would really matter to .999 (or more 9s if Canadian...). But getting to the more collectible coins, very concerned. A lot of the Albanian gold (.900) can be quite afflicted with the gold pox.

(not my coin, a nice high grade example with a horrible case of the pox):


I THINK this is one of the PCGS 65s. Here on their page, the featured coin is a 64. Also afflicted. I would have thought if it was safely correctable it would be a service offered before the slabbage.

https://www.pcgs.com/valueview/albania/1938-r-100-fra-marriage/945?sn=15106&h=pop