How to Remove the Mildew Smell from Books

Old books are wonderful treasures to find, and some can even be worth a lot of money, but they often come with a musty smell as well. Although it can be tough, you can remove, or at least reduce, that mouldy scent at home.

Edit Steps

Why books can smell mildewed or musty

Check for dampness. Dampness, wetness and total soaking of a book is the primary cause of mildew or mustiness in a book, providing an ideal growth medium for mold, bacteria or fungus (which can all smell bad). A spilled drink such as coffee or soda that wasn't mopped off carefully can stick pages together and nurture mildew growth. Dropping the book in the bath can cause total havoc, while leaving a book next to a damp wall without knowing can cause gradual mildewing. Storage of books can often result in bad odors from mildew. If you don't know whether or not the book has been wet in the past, some telltale signs include:
- Pages stuck together, especially around the edges but can be whole way through. Often chunks of pages can be stuck together, leaving others freely turning.
- Discoloration, such as brown or black speckling, yellowing, and the like.
- Actual mildew or mold growing on the spine or cover of the book, especially if the book is old and the cover is made from something totally organic, like leather or paper (no plastic).
- It smells like mildew or it's musty (smells like a damp cellar/basement).

Check for cigarette smoke damage. Another cause of a musty odor can be exposure to cigarette smoking. Books will look yellowed, may be speckled (brown spots running up and down page edges and often across inner pages of book; also known as "foxing") and there may be a stinky smoky odor as well as a musty one, depending on how long it has been since the book was in the smoky location (being absorbent, book paper can stink of cigarette smoke for years).

Fixing immediate sources of dampness

If upon picking up the book, you can feel it is damp and see wet or damp pages clumping together, deal with it immediately. The longer a book is left, the harder it will be to fix and the more likely mildew will grow.

Stand the book upright on a table. Fan out the the pages fanned gently. If your fingers can't disentangle pages without ripping, use a letter opener and tweezers to assist finer page separation.

Let stand to dry in a warm spot free of moisture. Leave long enough to ensure that every page is nice and dry.
- You could try direct sunlight if the book isn't valuable, just useful. However, be aware that direct sunlight may fade the book and for older, valuable books, could lead to disintegration, discoloration or curling up of the pages permanently. In most cases, warmth but not direct sunlight is the best approach.

Using an absorbent to remove moldy or musty odors

It's assumed that by this stage, you've dried the book or simply have a dry book and you now want it to be odor-free to enable it to be read again.

Try kitty litter. You'll need a large container, like a Rubbermaid tub and a smaller container, as well as an absorbent, like baking soda, cat litter, or charcoal.
- Fill the larger container halfway with kitty litter.
- Place your smelly book or books in the bottom of the smaller container. Place the container above the kitty litter inside the larger container.
- Seal the larger container tightly, and 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 down (a new paintbrush is ideal for dusting with). If not, repeat until the book smells a lot better.
- Store in a clean, dry place to avoid reintroducing the mildew or musty odor.
  - Activated charcoal or charcoal briquettes can be substituted for kitty litter in the method outlined above. Just be careful not to bring the book into direct contact with the charcoal or it may sustain blackening marks.

Try baking soda. Place a cup of baking soda into a plastic box or bin. Place the book or books (this method is great for more than one book) inside and seal the lid well. Leave for 48-72 hours, then check. Repeat until the odor has gone.
- Another approach if you live where it's dry heat and sunny: Sprinkle baking soda between the pages, perhaps every 10 pages or so. Leave the book open in the sunshine for a few days in a row (bring in at night). Sniff to see if it has improved and continue until it smells better. This won't work on all mildewy or musty odors, but it can be beneficial for some. (Be sure not to leave the book exposed to wind or rain.)

Try newspaper between the pages. Place a sheet of newspaper between every few pages of the book. Do not use on valuable or old books, only cheaper ones (newspaper is acidic and it may transfer ink to the book).
- Scrunch up balls of newspaper and toss inside a resealable plastic container or bag.
- Place the book in and seal or add the lid.
- Leave for 3-5 days.
- Remove all the newspaper. The book will hopefully smell better. Do not leave books wrapped in newspaper, as this can harm the book long-term.

Hiding the odor

Sometimes, no matter what else you've tried, the odor lingers. Here is where you can try to mask the smell and hope that the result makes reading the book bearable. Note that none of the following should be done with a valuable old book as the perfumes and chemicals in the items used to cover up the odor can introduce elements deleterious to the book's paper, and in some cases, the musty or mildewy odor might be better than ending up with a crumbling book! (Librarians and antiquarians look away now.)

Use fabric softener sheets. Just as these sheets absorb odors from fabric, they can do so for books too. Try the following:
- Cut a bunch of sheets into thirds, and put one between every 20 pages or so in your smelly book.
- Keep it in a zipper bag for a few days, and the musty smell should be gone.
- This method is good for preventing the musty smell across numerous books as well––just put a piece of a fabric softener sheet in about every fifth book on your bookshelf.

Cut a small square of fresh fragrant drawer liner. Place inside the book. You might like to use 2-3 pieces, depending on the size of the book.
- Place inside a resealable plastic bag. Let sit in a dry spot for a week or two.
- Check now and then to see if the fresher odor has been transferred to the book. Continue until the books smells a lot better.

Use a strong essential oil. Add drops of an essential oil like lavender, eucalyptus or tea-tree oil to some cotton balls. Place in a resealable plastic bag. Add the book and seal. Remove after a few days; you should find the book smells more like the essential oil than what it once smelled like. Due to the risk of oil spots, only do this with books that don't have great value other than needing to be read, such as a moldy-but-useful textbook.

Future storage

Check all storage areas before re-storing books anywhere. Ideally, the area should be dry and neither too cold nor too hot, as coldness can encourage dampness and heat can dry out paper and cause it to crumble. Humidity is bad all round, so find storage with low humidity or do something to reduce the humidity. And do not sit plastic containers in direct sunlight or near heat sources where they may develop condensation which has nowhere else to drip but onto the stored books!
- Check that bookcases are not up against moldy, cold and damp walls.
- Check the attic or basement for leaks, mildew and dampness.
- Check any storage facility for bad odors and signs of mildew or dampness before signing up to storage.

Use appropriate storage containers.
- Choose plastic boxes if the storage area is prone to leaks or dampness. However, add silica gel sachets in case of condensation.
- Don't fill bookshelves too full; allow some air circulation between books.
- Add dust jackets. These can help keep moisture away from the book. It's easier to replace dust jackets than the book cover itself or its binding.

Edit Tips

Some ways to kill mold, bacteria or fungi on books include:
- Microwave paperbacks. A quick zap might kill spores. Don't overcook though, you don't want a burning book.
- Thymol can be used to destroy some book molds but it requires special application; seek instructions from a bookseller used to dealing with it.

You can't change the color of a book from yellow back to white. The yellowing is due to the many decades of using paper with acid as one of the constituents (mid 19th century to end of 20th century) and eventually, this causes deterioration. Love the book while you have it and consider getting it digitalized if it looks like it's falling to pieces. In general, yellowing isn't a cause of musty or moldy odors but books all have their own unique scents and perhaps one of the above methods can improve a bad smell not initiating from mold/bacteria/fungus or smoke.

Edit Warnings

Dust from kitty litter might infiltrate the book and spoil it. Look for kitty litter without a lot of dust or only use the top portion from the package (hopefully the dust will settle more at the base of the package). Litter can also be caught in the spine or binding, depending on the type of litter used.

Overly dry pages in older books may cause them to tear more easily. Be careful about keeping books in too dry an environment for too long.

Cigarette and tobacco odor are very hard to remove. Months of sitting on a windowsill in warm sun and frequent page turning may go some way to helping but really, only time can help and even then, it may not be sufficient.

Valuable book and don't know what to do? Don't do anything; instead, take it to an antique book retailer for professional advice. Better safe than sorry.

Bleach of any sort will damage and perhaps even destroy books.

Not all musty odors are due to mold or mildew. If a book shows no signs of water damage or staining but still smells a bit like a dank, sour basement, the acids in the paper may simply have been excessively oxidizing. Such acid odor often results from books being kept near heat sources, on shelves that receive direct sunlight, or otherwise frequently exposed to heat, which accelerates the gradual damage that the paper's own acids do to it over time. If the book is a valuable collectible (e.g. a rare comic book or an antiquarian piece that is otherwise in great condition), you may wish to take it to an archival preservation or book restoration specialist. Regardless, you should not attempt to apply any form of cleaner to it.