Slabbed Cards

[steve B]

As Swarmee said, the slabs are probably just fine.

As hobbyists, we look at storage as a "what's the best thing for my situation" ok, we don't all say it that way but that's what it is. Even just a penny sleeve and toploader will protect a card pretty well for decades, maybe longer, but in general we don't know for sure. I used to worry about slabs and whether acidic cardstock would degrade and the acid would remain in the slab accelerating the process. If that was a shorter term concern, we'd have seen it by now. And the slabs are probably close to archival as far as materials go.

But a professional archive like the HOF shouldn't be looking a few decades down the road, more like centuries. Archival Mylar will be stable for a long time, and the other stuff a real archive uses isn't far behind.
The slabs may be just fine, but they haven't had the testing to know for sure.
As someone with a cheap but fairly large collection, just the space to have everything in slabs is a challenge. I don't have the space.
I also don't have a climate control system, mylar sleeves and special acid free boxes I'd like to, but the cost of the supplies would be too much.

Don't put Mylar sleeves in toploaders, between the two, they're smooth enough that the air gets out from between them, and they're very hard to get apart.