Meow is a fairly new collector. And has bought examples of older coins, and various graded holders to have an example, and a general feel for them. Meow has a question about various graded coins. The question is, are all graded holders safe for permanent storage? Besides leaving a holder exposed to direct sunlight, will all holders keep a coin safe from degrading under normal temperatures and humidity? So besides leaving one out on the dashboard of ones car in the blazing sun, or storing it in a sauna; Does one need to pay any special attention to storing a graded coin? This including all versions and generations of PCGS, NGC, and ANACs holders?
Slabs are not completely airtight, so gasses/moisture can still get in gradually. This is one of the reasons why NGC doesn't have an unlimited designation guarantee on RB or RD copper coins. They can darken in the slab. Slabs are very good protection for coins, but you still should keep them in a sealed temperature controlled environment with dessicant packs.
I had an MS64 Type 1 slabbed. At the time my coins were in my gun safe with the gun cleaning chemicals. That Type 1 began growing a nasty black spunge that I attributed to the cleaning chemicals leaching from the guns in that gun safe. It was an NGC holder. I do not believe they are airtight at all.
Thanks, that is good to know. Meow was concerned about such issues. But that is too bad, that a graded holder is not permanent insurance for a coin. So it is very possible for a coin to have been accurately graded, yet over time become overgraded because of deterioration?
About the only thing I would add to the comments that Jaelus made is that the same proper storage procedures apply to coins in any and all hard plastic coin holders. There is no such thing as a coin holder that will completely protect your coins. And none of them, absolutely none of them, are anywhere even close to being airtight ! I've posted the details for proper coin storage more times than I can count. A search using that term - proper storage - and my user name will bring up more than most care to read.
Absolutely ! Of course you also need to be aware that they are commonly, very commonly, grossly over-graded the when they are put into the various TPG slabs to begin with ! But that is an entirely different discussion.
That is unfortunate. What do you think about the long term storage of loose and OBW rolls in coin tubes? Are they any safer than the graded holders in your opinion?
The closest thing to an airtight slab is the newest PCGS one which is water resistant, but basically nothing on earth is truly airtight. The different companies and generations of slabs have various levels of protection and some are much much better than others. Possible yes, usually it's more of a color thing like a RD turns RB or RB turns BN.
Oh well, so much for feeling confident buying grading coins sight unseen. Meow heard that, that was one of the reasons for them coming up with graded coins in the first place. (Being able to buy sight unseen, by just the grade.)
Moisture is the big killer. I wrap my coins in a zip lock bag and then into a Tupperware box. My part of the country is quite humid.
Only my nice coins get the extra treatment. My common stuff simply resides in tubes and boxes. I zip lock bag my coin albums and the costly slabbed stuff gets the double treatment at my house.
Buying slabbed coins sight unseen has much greater problems than the potential that a coin has developed a problem while in the slab. Ignoring the problem of overgraded coins, you could have two correctly graded examples of the same coin where one is at the top of the grade (an A coin) and one is at the bottom of the grade (a C coin). Even further, you could have a technically high graded coin with drab toning and poor eye appeal. Having said that, sight unseen is frequently used to refer to seeing a photo of the coin but not being able to inspect the coin in person. In this way by seeing a photo and the grade on the slab, you can make a significantly better informed decision on buying a coin, based on how much you trust the TPG that slabbed it.
Every storage method involves a micro-climate that seeks to contaminate the surfaces of a coin. Those micro-climates are always trying to migrate inward and the best we can do is to slow them down.