Cards are thin, stiff and absorbent, which is a bad combination in a humid month.
What actually destroys them
Humidity, which swells the card inside its sleeve and can make the two stick. Heat, which curves it — and a curved card grades lower whatever else is true. Light, which fades borders and dulls surfaces. Pressure, which rounds corners in a tightly packed box.
What to do instead
- Sleeve, then rigid holder or a card box, stored upright
- Silica gel in the box, replaced when spent
- Inside wall, off the floor, away from windows
- Not sealed in plastic long term — a sleeve is protection, not an airtight seal, and that is correct
Graded cards
A slab handles humidity and bending far better than a sleeve, and handles impact worse. Upright, supported on both sides, out of the sun. A cracked slab is damage even when the card is untouched.
Bulk
Bulk still deserves a dry box. A box of commons that has been through two monsoons on a floor is a box nobody wants, and bulk is what fills a room at a show.
What it costs
Sleeves, boxes, silica. Compared with one card, nothing.
Questions people ask
Does a card curve straighten out?
Sometimes, slowly, in the right conditions. Do not count on it.
Is a safe a good place?
Only if it is dry. Safes can hold moisture.
What about during the monsoon?
Check at the start and the end, and replace the silica. Monsoon and your stock.