The musty smell on old baseball cards can be caused by a number of factors including mold, mildew, dust, and the storage conditions of the cards over a long period of time. Getting rid of this unpleasant smell can help preserve the cards and make them more enjoyable to look through. Here are some effective methods to try:

The first step is to carefully inspect the cards for any visible signs of mold or mildew growth. Use a magnifying glass if needed to check crevices and edges. Any cards showing mold should be isolated from the others immediately to prevent further spreading. Mold needs moisture to grow, so the humidity level where the cards are stored is important to control.

Once you’ve identified any moldy cards, you’ll need to carefully clean them. Wear latex gloves during the cleaning process to avoid transferring oils from your hands. Use a soft-bristled brush or dry cloth to gently remove any loose debris or visible mold spores. Make a mild cleaning solution by mixing 1 cup of white vinegar with 1 quart of cool water. Dip a clean cloth or cotton ball into the solution and gently wipe down the front and back of the card. Rinse with a separate cloth dampened with clean water and lay flat to air dry completely before returning to storage. The acid in the vinegar helps kill mold.

For musty smells throughout the entire collection without visible mold, you’ll need to use methods to reduce odors at their source. Carefully wipe down the interior and shelves of the storage box, drawer, or bin where the cards were kept with the mild vinegar solution. This removes any residual odors. Replace the lid or door when drying. Activated charcoal is also very effective at absorbing odors and can be placed in an open container alongside the cards in their storage area for 12-24 hours. Replace the charcoal every few months as it becomes saturated.

Another option is to make a homemade odor-absorbing spray by mixing 2 cups of white vinegar with 2 cups of water in a spray bottle. Lightly mist the solution onto clothing, upholstery or other fabrics that may be holding onto musty smells and air dry. Do not directly spray the baseball cards. Ozone generating devices and sachets are other commercial products designed to eliminate musty smells from enclosed spaces like closets and storage areas. Be sure to follow all safety guidelines if using these methods.

For severe musty odors that have really set into the paper fibers of the cards over many years, more intensive cleaning may be necessary. Wearing gloves, carefully wipe each card front and back with a 50/50 solution of water and hydrogen peroxide using a soft-bristled brush or cotton balls. Hydrogen peroxide is a natural bleaching agent that can help break down odor-causing molecules. Rinse well and air dry as before. As a last resort, very delicate surface cleaning of heavily stained areas may be done using a dropped of diluted dish soap in water, but rinse thoroughly to prevent residue.

Proper storage is key once cleaning is complete to prevent musty smells from recurring. Store cards in acid-free papers or sleeves inside a sealed plastic container or bin with a desiccant pack to control humidity levels below 50%. Rotate desiccant packs every few months as they become saturated. Avoid direct sunlight, high temperatures and other potential causes of mold growth. With regular cleaning and monitoring, you can banish musty baseball card odors for good and preserve your collection for many years to come. Proper handling is important, but with some patience these natural odor elimination methods should restore cards to their former glory.