How to Store US Dollars & Foreign Currency Without Mold: An Expert Guide

Have you ever stored a sum of US dollars or other foreign currency savings in a closet or safe, only to later discover horrifying spots of green and black mold, with the bills stuck together and smelling musty? In Vietnam's humid climate, this is a common risk for all paper currencies, from USD and Euros to Vietnamese Dong.

This article will serve as a comprehensive guide to help you protect your assets safely and scientifically.

1. Why Is Paper Money (Especially US Dollars) Prone to Mold?

The cause stems from two main factors: the material of the banknote and the storage environment.

• Due to the Paper Material: According to the U.S. Bureau of Engraving and Printing, the US dollar is made from a blend of 75% cotton and 25% linen. These are organic, plant-based fibers, which are a "favorite food" and an ideal environment for mold to grow.
• Due to the Environment: When the relative humidity (RH) of the environment exceeds 60%, mold and bacteria have the perfect conditions to thrive. Safes and closets are typically enclosed, dark spaces with little air circulation, which allows humidity to easily accumulate and rise.

2. The Consequences of Improper Money Storage

• Loss of Value in Transactions: Banks may refuse to accept or may charge an inspection fee for banknotes that are moldy, torn, or severely yellowed.
• Irreversible Damage: Mold doesn't just stain; it "eats away" at the paper fibers, making the bills weak, brittle, and easy to tear.
• Health Effects: Inhaling mold spores from money can cause respiratory problems.

3. A-Z Guide to Safe & Mold-Free Money Storage

Step 1: Prepare the Money Before Storing

Ensure the banknotes are completely dry and clean. If the money is damp, use a hairdryer on a cool setting or place it in front of a fan to dry it completely. Flatten the bills and avoid creases.

Step 2: Choose the Right Container

Do: Use clean paper envelopes or, ideally, specialized acid-free currency sleeves for the best protection.

Don't: Use rubber bands (which can leave marks and damage the paper) or regular plastic bags (which can trap moisture and "sweat" inside).

Step 3: Control the Storage Environment - The Deciding Factor

According to international standards for archival and paper document storage, the ideal environment requires a relative humidity maintained between 40% - 55% RH. This is the absolute safe threshold to prevent mold growth. Placing money in a safe or a sealed cabinet without controlling the humidity of the entire room still poses a very high risk.

4. The Optimal Anti-Humidity Solution for Storing Currency

For Individuals & Families

The Problem: Safes and closets are often located in bedrooms or offices—enclosed spaces with little sunlight that are prone to dampness, especially during the humid season.

Recommended Solution: The Olmas Home Dehumidifier.

Instead of using small, temporary desiccant packets, a dehumidifier will control the humidity of the entire room where you keep your safe. This not only protects your money but also all your other assets like designer clothes, important documents, and electronic devices. The Olmas line is officially imported with full CO, CQ documentation, offers competitive pricing, a modern design, quiet operation, and is backed by a 2-year warranty from DeAir.

For Businesses & Organizations (Vaults, Transaction Offices)

With larger amounts of cash and higher security requirements, businesses and financial institutions need more powerful solutions. DeAir has experience in consulting and installing specialized systems like industrial dehumidifiers for bank vaults, ensuring absolute security for assets.