Leave the book to sit in the absorbent for a few days. Check every few days. If the odor has gone, remove the book or books and dust off (a new paint brush is ideal for dusting). If not, repeat until the book smells better. Store in a clean, dry place to avoid reintroducing mildew.
Another approach if you live where it’s dry and sunny: Sprinkle baking soda between every 10 pages or so. Leave the book open outside during the daytime for a few days in a row, turning pages often. Continue until it smells better. This won’t work for all mildew or musty odors, but it can be helpful for some. This is not advised for valuable or antique books.
This method is good for preventing the musty smell of books as well––just put a piece of a fabric softener sheet in every fifth book, or so, on your bookshelf.
Check to see if the fresh odor has been transferred to the book. Continue until the book smells better.
Check the attic or basement for leaks, mildew and dampness. Check your storage facility for bad odors or signs of mildew before storing your book there.
