Feldpost preservation

[crochunter]

I'm trying to figure out the best way to store my feldpost collection. I've already gotten acid free document protectors, but what I do not know is do I store the letters unfolded or not. Right now they're kept folded inside their original envelope but I was told that if kept like that the pressure on the folds will keep up until the letter separates at the folds. Does anyone have any tips?

[AMTG]

I would recommend laying the pages out flat, then storing them in the acid proof sleeves, one page per sleeve

[crochunter]

I would recommend laying the pages out flat, then storing them in the acid proof sleeves, one page per sleeve

Thank you very much for the information.