Warping is one of the easiest ways to ruin a card’s grade.
Quick Rules
Avoid humidity
Avoid heat
Don’t leave cards in binders in hot rooms
Don’t leave cards near sunlight
Best Storage Options
Card savers
Top loaders
Semi-rigid sleeves
Card storage boxes
Climate-controlled display cases
Temperature Target
68–72°F with 40–55% humidity is ideal.
Warping is detectable by AGS laser measurements — so prevention matters.