Best conditions for allowing old copper to re-tone?

Picked up an old half cent that has been cleaned sometime in the last century or so. The high points are gold/brassy and I'd like to return them to chocolate brown but I want to do it properly. I understand the Smithsonian does something with the coins from their collection that have been cleaned in the past to allow them to re-tone naturally. Does anyone know their process? Temperature, humidity, sunlight? I once purchased a BU merc mid-day and by the time I got home that evening sunlight had turned the bottom 5% of the coin black(It must have been trying to get out of the envelope). Would direct sunlight do that to copper or could it be damaging? Any advice will be appreciated - though not necessarily heeded. Thanks

 

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Can you post a pic of the coin? The part about the gold/brassy part makes it sound not right.

 

No, I've got virus issues with my home computer and the site doesn't seem to want to
Let me add pics from my phone. Besides this specific example doesn't really
matter. Imagine wanting to re-tone any cleaned copper.

 

Best, (and least objectionable), advice? Throw it in a manila coin envelope, leave the top open, and put it away somewhere for 5 years.

 

The only way other than what mederoman said is there is a copper coin darkening called dwellers darkener. I haven't used it but several Google searches showed up with good results

 

I don' know if this is the best methsd, but I just leave them on a tray by a window sill (and hope my wife does not wipe them with a wet cloth when she cleans). She actually did that once, until I told her that she had just wiped over $20000 worth of coins.....

Anyway, i have observed that silver tones much faster than copper - this somewhat contradicts what I know about copper's reactivity (ability to oxidize), v.s silver. I have a few old coppers on the trays, and after a few years at least one of them is looking quite nice. It take a long time if you do it this way, but that is OK with me.

 

True, it has been used and basically has the same "ingredients" as my method.

I guess I am like Eduard, I am in no rush. These coins have been around for decades, centuries, millenia, why the rush? Better to do it stable and well than worry about getting instant gratification.

Deller's darkener is an ok product as chemicals go, but if you are going to keep the coin, or worry about future generations of collectors, I find it always best to do it naturally.

 

If you have virus issues at home, do everyone else on the internet a favor and unplug already from the internet (physically remove your internet connection that is). If you have virus issues on your machine, by staying online, you're only likely spreading the infection to any computer that is not secure in prevention of infection.

That's of course you already have and are posting from your phone or another device.

 

I am by NO means knowledgeable about this but I do know that I have seen cents with finger prints showing where it was held once and the fingerprint was dark from toning. I suspect that most brown toning is initiated by the oils from people's hands. If this is a correct assumption, then touch the cent thoroughly when you fingers have natural body oils and are not freshly washed. Set it in an acid paper wrap for about 2 years. I have no idea if that is the best way but it is a way.

 

Ok - I'm doing this from my phone and the viruses
Are from Facebook so they're already all over the web.
Touching the coin all over sounds crazy to me. I plan to set
This coin aside to age but my question was about more specific
Conditions- low humidity room in direct sunlight? in a drawer?
In a higher humidity room in an envelope? or open air?
I know this is an unusual problem but any experience helps.
Thanks guys

 

Do not touch it intentionally, warmth and humidity would help the process, but basically being in the manila will do it eventually.

 

I have actually heard putting it in molasses for a night and then an acetone dip will work. Never tried it myself, so before you consider trying it, grab a copper cent at random, clean it and then try it before you do a real value coin.

 

No, the fingers have very few oil glands ( Humans with slippery hands wouldn't survive well evolution wise. The fingerprints are initiated by sweat ( even insensible ( not visible) in the grooves. Bad Idea.

Some Molasses is treated with sulfur dioxide as a preservative, so you are just using sulfur. Much molasses is not , so you would just have a sticky coin. Using old fashioned match heads, Sulfur containing acne creams, Sodium sulfide and acetic acid, Deller's sulfur flowers ( flours) intended for garden soil, etc. is unpredictable and most likely will leave the surface much worse than now, so you have to dip again (bad) and try darkener again ( more bad) .

Besides use of any of these methods with intention to color the surfaces of the coin are artificial toning ( Oh my gosh, did I raise that argument again??) Even putting into a manila envelope with intent would fit in there by many. Besides once the toning starts, you have to find ways to stop it . Chemistry comes in handy.



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I would first suggest something that might help. Even out the toning (even if it lightens it) with some product like Verdicare, or a similar dip. Then allow it to tone by leaving it out in the air. Heating it might speed up the process, but would be tricky.

 

Since no one else has mentioned this, there are a few interesting "methods" explained in Penny Whimsy, especially for people who like dirty underwear (joke)

As has already been mentioned, Deller's does work for a quick fix, but I would highly advise you to experiment on lesser coppers first - particularly application techniques.

 

I appreciate the zeal with which these methods are being
suggested but I'm not going to do anything artificial. I want
no part of mixing chemistry and coins. Optimal ambient
conditions was what I was hoping to learn, not tricks. Thank
you for all of the input; I think I'm going to leave it out on a
windowsill in a moderately humid room and flip it every other
day. FYI the coin in question is an 1811 half cent and I'll try
to post the pics.

 

Finally got it

 

h8, any and all toning is the result of some sort of chemical reaction. It may be from the air or cardboard or paper or pvc or the hands, but all toning is chemical reaction. Further what ever else you do, the already toned portion will tone more as the high areas that have rubbed start to re-tone. I believe unless you "paint" or "rub" something on the high areas that will accelerate the toning on that contact area, it will always appear less toned.
The rest of my 2c worth, I wouldn't try to re-tone. The toning that has rubbed off the high areas is normal, just as the circulation wear is. Just let it be.

 

Now that pics are posted, the $64,000 question:
Would it grade?

 

Beautiful Coin! It may have just be lightly cleaned or dipped in the past. it kinda looks like a overdipped surface or corrosion. But with out looking at it in person i wouldn't be about to tell for sure. But i would saw it would grade FINE if it got graded.