Maybe this topic is talked about more often than I realize and I simply haven’t been made aware, I dunno. In any event, I wanted to condense (ha..ha..I’ve got jokes….) some insights on the impact of humidity on your tarot cards.
Ever notice how a wooden door seems to expand ever so slightly in the hot summer months? Musicians are all too aware of how temperamental wooden instruments can get depending on the weather and the humidity. Paper products like your tarot cards are made of cellulose fiber (derived from plant-based materials, like bark, wood, and leaves). They’re porous, causing them to be highly sensitive to humidity levels.
Cardstock absorbs moisture in the air.
Cardstock is hygroscopic, which means the cards, by their chemical (alchemical?) nature, will try to maintain an equilibrium with its environment, which means it’ll absorb water molecules in the air and also release its water molecules out into the air, to try and maintain that equilibrium. The temperature, humidity, and the climate of the region you live in have more of an impact on the durability of your tarot deck than you may realize.