Flattening 3D cards

[Exhibitman]

I agree that the 1970s seem to be quite stable. My 1970s have been in card savers inside 4 pocket sheets in binders for many years without curling or cracking. I also have an SGC 88 Mays that is doing fine. I even picked up a Richie Allen out of a junk box at the Natty w/o any issues, and it had been floating free w/o a holder for who knows how long. That said, I have seen TPG slabbed cards with cracks and high grades, so they can crack after being encapsulated. I've put some mildly curved cards into card savers/sheets w/o trouble. I try not to purchase cards with significant curvature in the first place, as I am concerned with cracking, and there are enough examples out there to avoid the ones that have rolled up.

[theseeker]

I am a big Kelloggs collector and have always used the rigid top loaders for straightening. Never have had one crack. I've bought slabbed sets and lots with cracked cards and have always wondered how long after grading did the cracking occur.

Sadly, even more common than curling/cracking is the fading of the 3D effect. I distinctly remember how vibrant they looked right out of the cereal box and all have lost their original luster to some extent.

Oh and one more thing, these cards do not like cool, dry storage areas like basements during the winter.