To remove a musty odor from home furniture may require a bit of work and patience depending upon how severe the odor is and if there is actual mildew. These smells can be extremely difficult to remove permanently in some furniture, but there are things you can try.
Step 1 - Dry It Out
Musty odors are generally caused by upholstered furniture that has become wet and didn't dry out completely or from excessive moisture in the air where the furniture has been. The musty smell is a form of mildew and mold. The first thing you must do to get rid of this smell is destroy the mold and mildew. Move the furniture outside on a warm, dry day and let it sit in the sun. If it has seat or back cushions that can be removed, remove them and air them separately. Turn them several times during the day. If by chance there is a slipcover on the furniture, remove it and launder it in the hottest water possible without ruining the fabric and let it line dry. You should add 1 cup of vinegar to the wash water to deodorize it. You may need to leave the furniture sitting in the sun and fresh air for several days to greatly reduce or eliminate the smell.
Step 2 - Remove the Odor
An important thing to remember is that you want to remove the odor, not just cover it up. After you are certain the furniture is completely dry, mist it with a mixture of one-quart water and ¼ cup of white vinegar and allow it to sit outside until it is dry again. This treatment may take several applications on heavy odors.
Another way to remove musty odor on pillows, draperies, and small fabric items is to place them in a large trash bag with a handful of coffee beans. Seal the bag and let it sit for several days. You may need to put them in the sun and fresh air again for a while after this process.
Step 3 - Deal with Persistent Odors
After you have taken the above steps and the odor still hasn't left you may need to purchase a commercial odor remover and use a steam type carpet cleaner to clean the upholstered furniture. Follow manufacturer’s recommendations on the proper amount of cleaner to add to the cleaning water. Clean the furniture thoroughly with this mixture and allow it to dry. Good commercial odor removers are available at many janitorial supply houses and pet supply stores.
Some commercial odor removers come in concentrated form in small spray bottles. You may find with a strong, persistent musty smell you may need to spray the furniture occasionally with one of these products.
Step 4 - Evaluate Mildew
Since the musty smell is caused by mildew or mold, be careful if anyone in your family has allergies as many people are very allergic to mold. It’s important to know whether it is a mild case that merely requires a bit of freshening or if there is mold lurking inside the furniture. If the later is the case, consider getting the furniture professionally cleaned or discard it.