Aren't the slabs airtight?
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I have 5 coins -- 4 Presidential Dollar proofs (2 PF69, 1 67, 1 66) and a 2010 Cent (PF69) that are starting to show some discoloration similar to the kind a Sac Dollar would experience while in circulation. I've always thought the slabs are airtight... Has anyone else experienced this before?

 

The coins were slabbed earlier this year. It's unlikely that it's the way they came in the proof set as discoloration that's painfully obvious isn't likely to grade 69 UC!

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NO

 

Q. After encapsulation, can the appearance of a coin change over time?

 

A. Yes. In independent testing, the NGC security holder has been proven as the most effective grading service holder on the market today in minimizing the effects of oxidation. Even so, the NGC holder is not 100% airtight. Therefore oxidation, a normal process where air reacts with the surface of a coin, can continue after encapsulation. To further limit environmental hazards, we recommend storing your coins in a temperature-controlled, low-humidity area such as a bank safety deposit box. Be sure to check with your bank for rules and regulations concerning the storage of these items.

 

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I was flipping through channels on the tube the other day and came across one of the network coin shows. I realize that 90% of what these folks drone on about is hyped but when combined with this thread, it made me start to wonder. The guy on TV was making his pitch and was saying "buy the coin, not the holder". In other words, if a coin was slabbed 5 years ago, maybe it wouldn't receive the same grade today that it did back then. I am fairly new to the hobby, but my understanding was the slabs were air tight, and the purpose of the slab was to preserve the grade of the coin. Any thoughts from you more experienced folks on this?

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Jamie is one of the more experienced board members, and he is 100% correct. That's part of the reason that coins can continue to tone in the slabs. In another post to prove the same point, Jamie dipped one of his details graded modern coins in water to prove that there are not airtight; a large pocket of water became lodged in the slab. The slabs are definitely not 100% airtight.

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You also have to remember that once a coin starts a change before being encapsulated, that change is slowed down but not completely halted, so you may see actual change after encapsulation. It's the nature of the beast.

 

The only way would be to encapsulate a pristine example in a chamber utilizing a inert gas. Even then, after time, the encapsulated inert gas will leach out and exchange with the ambient air, but you'll probably be dead by then so it's the next owners problem.

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i have a pcgs 1881-s morgan that when i bought had a little more than slight toning around the rim, a nice reddish color. over the past year it has drastically changed to the entire obverse surrounding liberty is now covered in the red color, which i think is a good thing. I don't know how this can happen, i keep my certified coins in either NGC or PCGS box and in my safe. oh well

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I asked NGC this past week. This is the reply I got.

 

Mike,

 

Thanks for the question. While NGC holders are virtually airtight (and watertight), there can be some variance between individual slabs.

 

 

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i have a pcgs 1881-s morgan that when i bought had a little more than slight toning around the rim, a nice reddish color. over the past year it has drastically changed to the entire obverse surrounding liberty is now covered in the red color, which i think is a good thing. I don't know how this can happen, i keep my certified coins in either NGC or PCGS box and in my safe. oh well

 

Usually if you properly store slabs, they will not tone that quickly or that much at all for that matter. This makes me think that something may have been done to your coin chemically prior to encapsulation.

 

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Several years ago Coin World did extensive tests on the slabs of the major grading servicesfor a detailed article and found that none were totally airtight although the NGC slabs came closest to being airtight. Remember that when the barometric pressure rises, air will enter the slab and when the barometric pressure drops, air will leave the slab resultingin a constant change of the air in your slab. Also, if a coin were dipped and improperly rinsed prior to slabbing, the residual dip on the coin's surface will cause the coin to discolor over time even though it's housed in a slab.

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Hi All.

I am pretty new here, and can seldom see my post. Still trying to figure this stuff out. Back on this subject... I have a question? I have been collecting coins for around 5 years now. I have had them in storage for 2 years now without seeing them. They have been inclosed, however have been in summer temps and winter temps as low as 0. I am getting around to getting them out within the next 2 months. I just wonder how it has affected the toning, If At All, on my coins. BTW, Some are slabbed, some not.

I will post when I get to them them out. I'm thinking about selling all my coins, among other things I have. I just don't have the time anymore...

Jim

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Even if the slabs leak air, and toning takes place, am I correct in that it will not affect the grade given to the coin during it's encapsulation? Again, I am pretty green to collecting, but based on what I have read about grading criteria, it seems that the grade assignment has more to do with the surface condition of the coin (wear, scratches, etc.) vs. the coloration of (or lack thereof) toning... Somebody steer me back to the straight and narrow if that's not correct!

 

Thanks,

 

 

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Even if the slabs leak air, and toning takes place, am I correct in that it will not affect the grade given to the coin during it's encapsulation? Again, I am pretty green to collecting, but based on what I have read about grading criteria, it seems that the grade assignment has more to do with the surface condition of the coin (wear, scratches, etc.) vs. the coloration of (or lack thereof) toning... Somebody steer me back to the straight and narrow if that's not correct!

 

Thanks,

It is possible for post-slab toning to affect the grade, yes. If improper rinsing was done, the appearance can be spoiled, damage can occur.

 

Copper can change as well, affecting the color grade.

 

Or there can simply be a degraded look to the coin.

 

In most cases the TPG guarantee affords protection with the likely exception of copper color (long story).

 

All factors are taken into account when grading. Surface condition, luster, color, strike, toning and eye appeal. Even the location of bag marks. It's a complicated task, which explains why many experienced collectors still struggle with grading.

Lance.

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Thanks for the clarification Lance.... I feel pretty overwhelmed when it comes to trying to pin down a grade on a coin.... Well, I guess even I can tell a F from a BU, but trying to define a MS 65 from a MS 67.... no way!

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I am only supposing here, but if you have a number of NGC graded coins, would it be acceptable to display them in a wall cabinet made for slabs, or just leave them in an NGC plastic box?

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23 minutes ago, Mr.Bill347 said:

I am only supposing here, but if you have a number of NGC graded coins, would it be acceptable to display them in a wall cabinet made for slabs, or just leave them in an NGC plastic box?

Just realized this thread is going on ten (10) years old! In any event, here's my contribution:  it is the TPGS' grading rooms that are hermetically sealed not the encapsulated products.

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58 minutes ago, Mr.Bill347 said:

I am only supposing here, but if you have a number of NGC graded coins, would it be acceptable to display them in a wall cabinet made for slabs, or just leave them in an NGC plastic box?

Just my 2 cents, but, if you're keeping slabbed coins in an appropriate wall display cabinet - which is to say the materials the wall cabinet are not off-gassing with stuff that will corrode or color the coins - and you leave the cabinet closed most of the time in an air conditioned space / house then you should be fine. The slabs will severely limit air exchange with the surroundings and the cabinet will further limit it. So unless the space is overly hot and or humid- which is bad for copper and manganese brass keeping color - I doubt you'd have a problem. Any change is likely to be very slow unless the coins already had a chemical or toning agent on them.

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10 hours ago, Revenant said:

Just my 2 cents, but, if you're keeping slabbed coins in an appropriate wall display cabinet - which is to say the materials the wall cabinet are not off-gassing with stuff that will corrode or color the coins - and you leave the cabinet closed most of the time in an air conditioned space / house then you should be fine. The slabs will severely limit air exchange with the surroundings and the cabinet will further limit it. So unless the space is overly hot and or humid- which is bad for copper and manganese brass keeping color - I doubt you'd have a problem. Any change is likely to be very slow unless the coins already had a chemical or toning agent on them.

What about the formaldehyde manufacturers inform you about in small print with stickers attached to wood file cabinets and bookcases?  The ubiquitous California Prop[osition] 65 Warning, too, is hardly encouraging: lt reads:  "This product contains chemicals known to the State of California  to cause cancer and birth defects or other reproductive harm."

Of course, you only learn about all this after you've purchased the product and examined the warranties, restrictions and disclaimers of responsibility which accompany it.

If simple, largely stationary, furniture items have the potential to do that to your body, what can the emission of gases do to the raw and encapsulated coins contained within them?

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6 minutes ago, Quintus Arrius said:

What about the formaldehyde manufacturers inform you about in small print with stickers attached to wood file cabinets and bookcases?  The ubiquitous California Prop[osition] 65 Warning, too, is hardly encouraging: lt reads:  "This product contains chemicals known to the State of California  to cause cancer and birth defects or other reproductive harm."

Of course, you only learn about all this after you've purchased the product and examined the warranties, restrictions and disclaimers of responsibility which accompany it.

If simple, largely stationary, furniture items have the potential to do that to your body, what can the emission of gases do to the raw and encapsulated coins contained within them?

Well, there is a reason why I put those caveats in there. As far as formaldehyde and off-gassing goes, that's normally something that will occur for a certain period of time - a couple of years, slowly, I think - and then it drops off as the amount of residual formaldehyde is depleted. Not that I think anyone wants to buy a cabinet and spend the next 3 years letting it air out before they use it.

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1 hour ago, Revenant said:

 

 

 

1 hour ago, Revenant said:

... Not that I think anyone wants to buy a cabinet and spend the next 3 years letting it air out before they use it.

Well, it's been over three years now.  The distinctive odor is gone now -- and so are my migraines.  Thanks for the feedback!

Edited by Quintus Arrius
Deleted preceding post due to duplication
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3 minutes ago, Quintus Arrius said:

Thanks for the feedback!

As a Chemical Engineer, material aging is an interesting thing to look at. I'm actually going to be writing / posting soon about something involving plastic embrittlement that got a little comical. lol

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9 hours ago, Revenant said:

As a Chemical Engineer, material aging is an interesting thing to look at. I'm actually going to be writing / posting soon about something involving plastic embrittlement that got a little comical. lol

There are several published papers regarding long term plastic degradation - especially of artworks made in the late 1940s/early 50s.

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11 hours ago, Quintus Arrius said:

What about the formaldehyde manufacturers inform you about in small print with stickers attached to wood file cabinets and bookcases?  The ubiquitous California Prop[osition] 65 Warning, too, is hardly encouraging: lt reads:  "This product contains chemicals known to the State of California  to cause cancer and birth defects or other reproductive harm."

Of course, you only learn about all this after you've purchased the product and examined the warranties, restrictions and disclaimers of responsibility which accompany it.

If simple, largely stationary, furniture items have the potential to do that to your body, what can the emission of gases do to the raw and encapsulated coins contained within them?

I noticed recently that among cancer causing agents in California is 'wood dust'. Wouldn't that cause cancer in Indiana 🤢

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As far as the slabs go they should invent a slab with a  gasket around the edges. Like a thin o ring or something to help seal the moisture and air out of it. It would better protect the higher end coins. 

Edited by Hoghead515
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18 hours ago, Hoghead515 said:

As far as the slabs go they should invent a slab with a  gasket around the edges. Like a thin o ring or something to help seal the moisture and air out of it. It would better protect the higher end coins. 

True, but wouldn't they be expected to degrade over time?  O rings... hmmm, now where have we all heard about them before?

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On 3/7/2021 at 9:46 PM, Mr.Bill347 said:

would it be acceptable to display them in a wall cabinet made for slabs, or just leave them in an NGC plastic box?

It is acceptable to display them any way you want to.

 

On 3/8/2021 at 9:35 AM, Quintus Arrius said:

  "This product contains chemicals known to the State of California  to cause cancer and birth defects or other reproductive harm."

California "knows" that everything causes cancer or reproductive harm.

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