[scottbdoug]

In a way, yes they protect them from wear and tear from handling. But in the long term, the chemicals in the plastics that encase your card will react with the paper, or other material the card is made of, and break it down. It is a very slow process but it is occurring immediately once the plastic comes in contact with the card. Don't believe me? Well any librarian archivist know this. It's basic knowledge. The standard for protecting objects such as sports cards or other paper products is to use an inert plastic such as Mylar. It does not react to the paper when it touches it.

So if you think that all those hundred and thousand dollar cards are safe inside those slabs, think again. If you need more proof on what I am saying, just think that the most prestigious archivist of sports cards, that is, The Baseball Hall of Fame, removes the cards they receive as donations from their encased slabs as soon as they receive them. Sports Collector's Digest has an interesting article on this subject that is an informative read:

Baseball HOF Tackles Conservation for Collectibles With Revealing Information


It might be time to demand PSA, SGC, and other grading companies use inert materials when slabbing cards, or perhaps put the cards in Mylar sleeves before encasing them in the plastic holders.

[DrMitchJ]

I know that in the comic book grading/slabbing companies, the book is in a Mylar sleeve before being placed in 'the well' and sealed within a proper temp/humidity environment. I always assumed (never assume ... it make an ***** out of U and ME) that the inner sleeve was Mylar.
Even if it is plastic, I've seen some really yellowed disgusting plastic bags that housed some perfectly good and very old comics. And the comicbooks' newsprint was much more vulnerable to plasticizers than the baseball cards' cardboard.
In a perfect world, Mylar is used, but even Mylar in high humidity and heat isn't perfect. Heat, direct sunlight, humidity and insects are the worst enemy of paper.

[crossada]

My BGS slabs have a sleeve put on before they slab it.

[uvaspina]

I wonder if the card's ACTUAL condition makes much of a difference once it's slabbed as a 9.5 or 10. I mean, what's a dollar worth and why? It's worth a dollar because the U.S. says it is (and everyone accepts that).

[oneofakindcards]

At that point, one's really only paying for a grade and not the card (which is no longer the same grade)

But this is how plenty of people think to begin with.

I wonder if the card's ACTUAL condition makes much of a difference once it's slabbed as a 9.5 or 10. I mean, what's a dollar worth and why? It's worth a dollar because the U.S. says it is (and everyone accepts that).

[uvaspina]

At that point, one's really only paying for a grade and not the card (which is no longer the same grade)

But this is how plenty of people think to begin with.

I think I'd share your concern more if the slabbed cards were susceptible to relatively quick deterioration (e.g., like the disappearing Sweet Spot autos). It sounds like it's something that's happening on a microscopic level and, even then, would take decades before we actually would notice. In the meantime, the card would still be a "10" in everyone's eyes (and could be traded and sold, and resold) because PSA says so.

[bengalsandreds]

Interesting article. Makes you think about how your collection is stored.

[oneofakindcards]

I think I'd share your concern more if the slabbed cards were susceptible to relatively quick deterioration (e.g., like the disappearing Sweet Spot autos). It sounds like it's something that's happening on a microscopic level and, even then, would take decades before we actually would notice. In the meantime, the card would still be a "10" in everyone's eyes (and could be traded and sold, and resold) because PSA says so.

Sounds like 100-200 years in the future, people will start re-slabbing... that's if the hobby survives that long!