Mold is a fuzzy fungus that can develop in a warm, poorly ventilated area where humidity exceeds 60 percent. The water content in the air gives mold a chance to grow and even thrive if there is a substance such as paper to feed on. Books, stamp collections and sports cards are susceptible to mold or mildew damage, which can include discoloration, paper disintegration and a foul smell. Careful drying and cleaning is the only solution.
Dry the cards to kill mold spores and stop the fungus from spreading. Place the cards with the picture side facing up on a towel or bedsheet. Air-drying indoors works best.
Use a hair dryer to speed the drying process. Keep moving the hair dryer over the cards briskly to prevent overheating as this could cause discoloration and make the card stock brittle. Work carefully, flipping the cards to dry both sides.
Use a vacuum with a crevice tool or a hand-held vacuum to draw off as much of the dried, dead mold as possible. Hold the cards down at the edges with your fingertips. Make sure to vacuum both sides.
Rub a clean, lint-free cloth over the surface of each card to remove any remaining mold.
Protect your collection by placing the cards in protective sleeves and storing them in a dry location with temperatures from 60 to 70 degrees Fahrenheit. After cleaning, you may notice a greenish-brown stain in some areas where the mold has eaten into the card stock. There is no known way to remove this type of stain without damaging or destroying the card.
Never dry trading cards in direct sunlight or by placing in a windowsill, as this will cause the colors to fade and the card stock to curl and crack.