Do silver coins inside NGC slabs tone?

Discussion in 'Ancient Coins' started by pprp, Sep 14, 2019.

  1. pprp

    pprp Well-Known Member

    I have an owl tet inside a slab which has the usual hoard appearance, meaning no toning at all, silver white from over cleaning. lf~2.jpeg I would like to keep it in the slab as it is convenient to show it to non collectors without worrying about it getting dropped/ bumped... So will it ever tone inside the slab? :bored: Does anyone have any experience!?
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  3. -jeffB

    -jeffB Greshams LEO Supporter

    Over in the US sections there have been many threads about artificially toned coins, including toning coins inside slabs.

    Today's slabs are not airtight, so gases that cause toning can get in. I don't know, though, whether the toning that results would look acceptable.

    Having said that, I could look at your coin in its current state all day. :)
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  4. Mat

    Mat Ancient Coincoholic

    It will tone, but probably only slightly & it will take a very long time for it to even start.
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  5. ToughCOINS

    ToughCOINS Dealer Member Moderator

    I know that many bright silver coins toned (re-toned?) in the older NGC slabs, but I've been told that NGC had the inserts reformulated years ago to inhibit such toning in more recent generations of their holders.

    This information did not come from the horse's mouth, and can be considered little more than heresay.
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  6. cpm9ball

    cpm9ball CANNOT RE-MEMBER

    When the Mint decided to release the 2001 Kennedy's in $100 Mixed P&D bags in 2004, I bought some of the bags. This coin has been in an NGC slab for almost 15 years. Ordinarily, you might think that copper would tone just from contact to the air, but this coin is as bright, today, as it is in this photo that was taken in early 2005.
    2001-D 50c REV Slab.jpg
  7. ldhair

    ldhair Clean Supporter

    Every coin is different. If the surfaces were stable when it was slabed, it probably won't change much. A freshly cleaned coin has the most chance of changing.
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  8. John Anthony

    John Anthony Ultracrepidarian Supporter

    Do you think it's overcleaned? Here's what an uncleaned owl looks like, with what they call a "find patina"...

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  9. Silverlock

    Silverlock Well-Known Member

    Absolutely will happen unless steps are taken to prevent it. The sonic sealing is neither vacuum sealing nor guaranteed air tight. If you don’t want a coin to tone in a slab observe the same practices you would with a BU US silver dollar.
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  10. Severus Alexander

    Severus Alexander Blame my mother. Supporter

    I agree with the comments above that toning in the slab will be very slow. If you'd like the coin to tone nicely, I recommend cracking it out and storing it in an Abafil case. Here's a few years' worth: Screen Shot 2019-09-14 at 1.22.26 PM.jpg
    Last edited: Sep 15, 2019
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  11. Suarez

    Suarez Well-Known Member

    Generally speaking, silver toning is due to the chemical reaction with ambient sulfur and not atmospheric oxygen. Plastic is an effective barrier against sulfur so there should be very little if any toning of high grade silver coins.

    However, the seals in a slab are less effective at preventing oxidation on copper though still, of course, far less than if left out in open air.

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  12. -jeffB

    -jeffB Greshams LEO Supporter

    As I understand it, the problem isn't with gases permeating the plastic (in which case oxygen might well get through better than hydrogen sulfide or sulfur oxides); it's with gases filtering through physical gaps in the packaging, which is about equally quick for any gas you care about.

    We've seen plenty of examples of coins that were deliberately toned in their slabs. The obvious ones are the ones where the toning looks quite unnatural. I don't know if there are natural-looking ones.
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  13. Suarez

    Suarez Well-Known Member

    That's probably true Jeff. I didn't consider the possibility of intentionally trying to tone a silver coin inside a slab but there's probably several ways of doing it.

    Just thinking off the top of my head, one way might be to gently heat the slab next to hot brine. The coin, being metal, expands as it's being heated drawing in the brine vapors which bring with it trace amounts of iodine, chlorine and bromine which in turn create photosensitive salts. Light darkens these and creates the rainbow effect depending on the local depth of these compounds (varying depths absorbing and reflecting light at different wavelenghts).

    Again, just taking a mental shot at this.... I have no slabs to experiment on :)

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  14. johnmilton

    johnmilton Well-Known Member

    I have a 1796 dollar that was dipped white. It’s been in an NGC holder for about 20 years. It’s been toning over the last couple of years, and it’s looking better. :) The coin is an AU-50.
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  15. Sallent

    Sallent Live long and prosper


    That's one sexy owl. Got to love that hoard patina.
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  16. panzerman

    panzerman Well-Known Member

    I bought around 50 Morgan/ Peace Dollars (all MS) from Paramount Coins. All of them where from a large hoard stored in original mint canvas sacks. All where absolutely perfect/ no toning/ defects. I still have them today, in my saflips. They are still perfect, like they where minted day before.
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  17. pprp

    pprp Well-Known Member

    Yes unfortunately most of the hoard coins have been stripped clean of deposits/ patina etc....
  18. pprp

    pprp Well-Known Member

    Thanks for your replies...I will stick with the slab for the time being and if I decide to break it free I will post the images! I think most of the non collectors like the bright surfaces without toning maybe that's why the hoard conis were cleaned that much:banghead:
  19. savitale

    savitale Active Member

    Unless there is some sort of residue on the coin, toning in the slab will be extremely slow under normal circumstances. It will take decades to see an appreciable difference.
  20. Paul M.

    Paul M. Well-Known Member

    It's good that the labels and inks are now less reactive with coin metals, but you can still get toning from environmental sources. I know you know this, Mike, but unless you store your coins in a hermetically sealed environment under dry nitrogen, at some point they may tone. Even minimizing humidity and using some sacrificial copper cents to intercept oxidants won't necessarily stop all toning.

    I've got coins I've owned forever that haven't toned a bit, and I've got coins I've had for around 2 years that have toned a little. (I'm not counting the few coins I've got stored in paper envelopes, some of which have toned, some which have not.) It seems random, as they're all stored in more or less the same environmental conditions.
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  21. jamesicus

    jamesicus Supporter! Supporter

    I do not know very much about this subject, but for what it is worth here is a coin that I own:

    Charles II (1660-1685) milled Silver Threepence (1677)

    Diameter: 17.58mm, Weight: 1.43gm

    Note: as purchased - stored in a pH neutral paper coin envelope for approx. three years.
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