How to Keep Money From Molding & What to Do If It Does

Maintaining physical currency is important, as bills degrade over time due to environmental factors. Mold presents a significant threat, potentially rendering money unusable or difficult to exchange. Understanding conditions that foster mold growth and implementing proper handling and storage techniques preserves currency integrity and value. This article provides guidance on preventing mold on currency and outlines steps to take if it occurs.

Why Money Develops Mold

Paper currency provides a suitable environment for mold to thrive due to its composition and common exposure to environmental elements. United States banknotes are primarily made from a blend of 75% cotton and 25% linen, which are organic fibers. These materials serve as a food source for mold spores when conditions are favorable. Mold spores are ubiquitous in the air, but they require specific conditions to germinate and grow.

The primary factors contributing to mold growth on currency are moisture, warmth, and a lack of air circulation. Relative humidity levels above 60% create a sufficiently damp environment for spores to activate. Combined with temperatures ranging from 68 to 86 degrees Fahrenheit, these conditions accelerate mold development. Storing currency in confined or poorly ventilated spaces further exacerbates these issues by trapping humidity and heat, making it an ideal breeding ground for fungal colonies.

Preventative Storage Methods

Preventing mold on currency begins with controlling its storage environment, focusing on humidity and temperature regulation. Ideal conditions for currency storage involve maintaining a relative humidity below 50% and a stable temperature, ideally between 60 and 75 degrees Fahrenheit. Using desiccants, such as silica gel packets, within storage containers can help absorb excess moisture and maintain these lower humidity levels. Climate-controlled environments, like those found in most residential living spaces, are generally more suitable than damp basements or hot attics.

The choice of storage container is equally important in preventing mold growth. Airtight, acid-free archival sleeves or envelopes are preferable, as they protect bills from environmental fluctuations while allowing some air exchange to prevent moisture trapping. Avoid storing currency in conventional plastic bags or containers that can trap moisture and chemicals, which may degrade the paper over time. Always ensure your hands are clean and completely dry before handling money to prevent transferring oils or moisture to the bills.

Actions for Wet Currency

If currency becomes wet or damp, immediate and careful drying steps are necessary to prevent mold formation. The goal is to remove moisture quickly without damaging the bill’s integrity or security features. Begin by gently separating individual wet bills and laying them flat on a clean, dry, absorbent surface, such as a paper towel or a clean cloth. Ensure there is adequate airflow around each bill to facilitate drying.

Positioning a fan on a low setting to circulate air around the drying bills can expedite the process, but avoid direct, strong airflow that might blow the bills away. Alternatively, place the damp currency between layers of absorbent paper, like blotter paper, and apply light pressure. Never attempt to dry currency using direct heat sources such as irons, microwaves, or direct sunlight, as this can cause irreversible damage, including shrinking, burning, or compromising the embedded security threads and watermarks.

Addressing Moldy Currency

When currency already exhibits mold growth, direct intervention to “clean” the bills is generally not recommended due to potential health risks and further damage. Attempting to wipe or scrub mold can spread spores, damage the paper fibers, or remove security features. Severely moldy bills may pose a health hazard due to airborne mold spores and might not be accepted by financial institutions.

For heavily damaged or mutilated currency, including bills affected by mold, the U.S. Department of the Treasury’s Bureau of Engraving and Printing (BEP) is the authority responsible for examination and redemption. You can submit such currency to the BEP for review and potential exchange, though a significant portion of the bill must be identifiable. For currency with only minor mold or slight damage, local banks may accept the bills for exchange, but this is at their discretion. It is advisable to handle moldy currency with gloves to minimize exposure to spores before seeking professional assessment or exchange.