Warped cards

I received some old trading cards from a friend and some of the holofoil cards were warped. I read up that this can be due to the temperature in the room, ambient moisture and various other factors as well.

Even though I have only started collecting, I am not aiming to sell any of my cards, but is there any way of:

A - Re-flattening them without damaging the card
B - Preventing them from warping again.

If you mean curved, I’ve had success putting a card under a stack of textbooks in a cupboard with silica beads to remove moisture.

I will do as soon as I am able to lay hands on a camera of some description

And by warped, I mean that, if you were to look at card sideways on, it would not be completely flat, but would have a curve in it.

Ah yes, that’s exactly what I meant. How long did you leave it for?

I usually just sleeve them and place them in binders. If the binder is heavy enough that will usually straigten the cards out in not time.

I left them there for a month or two and forgot about them. Good as new!

If the cards are holographic it is due to the foil. Temperature plays a factor as foil (along with all metals) contract in the cold and expand in the heat. I’m not 100% sure if that is why foil cards tend to curve inward but it would make for a fun test! Time to stick some duplicates in the fridge!