Proper way to store books. Mold can grow in settings where there is too much humidity. Moisture may quickly ruin books and other papers. A book absorbs moisture from the air in a similar way to a sponge. Curled pages, a warped book spine, and mold damage are all examples of possible harm. Excessive moisture can also cause “foxing,” or the browning of a book’s pages. We suggest storing books in boxes or on shelves in a climate-controlled room.