I stored my cards in cardboard boxes until I was completing a 1975 Topps Baseball card set. What I should have done was… put cards in great condition in sleeves to prevent damage like corner dings as I organized them and put higher value cards in either top loaders or one touch holders.
If you plan to buy any of these, do me a favor and use the links below (Amazon gives me a credit at no cost to you – so that’s an easy way to helps support this site – thanks!)
Soft Card Sleeves
These are thin polypropylene (polypro or plastic) sleeves. Also known as Penny Sleeves because they’re cheap, they’re the front-line of protection for cards. They’re a good fit for 1975 Topps cards (3.5” x 2.5”).
They’re advertised as archival-grade, acid free and non-PVC> I’ve read that means they’re not supposed to leech chemicals into the cards.
Using sleeves helps prevent corner damage if you drop a card. Collectors put cards in sleeves and then in a top loader. That does two things: protects a card’s surface from scratches when storing in top loaders and protects against UV rays (top loaders usually don’t have UV protection).
I heard good things about Ultra Pro being a quality sleeve so they’re the brand I use. I’ve had good experience having used hundreds of these. I’ve bought from Amazon (usually fulfilled by Amazon and supplied by various dealers) and for single packages I’ve always received Ultra Pro (shipped from Blackstone Owl). But when I ordered a multi-pack, I once got BCW so I’d suggest you message the supplier before ordering to check if they supply Ultra Pro (if that’s what you really want).
I found inserting cards into sleeves annoying: the first corner goes in easy but the second corner gets tricky. I found “Easy Grade Card Sleeves” but read that some users feel the corner is cut is too big (it doesn’t adequately protect the corner since it has a ¼” cut). I also read about people cutting corners themselves, so I started to do that (making a much smaller cut then ¼”) and it helps. It’s a pain in the butt, but it’ll save hassle when sleeving cards. And the corner isn’t exposed.
There’s also a Premium Card Sleeve, which is thicker and more expensive. I don’t see the benefit. If you want more protection, use a Top Loader.