Many things can lead to mold growing in a gun safe, but the main reason is almost always humidity. Luckily, with a little maintenance, as well as some simple, cheap, cleaning solutions and specialty tools, which you can find in most local gun shops or Internet gun supply stores, mold on guns can become a thing of the past.
Cleaning Existing Mold
If you have existing mold, you should wipe down everything, including the inside of the safe and your guns, with a mild chlorine solution. When you are done cleaning with the solution, let everything dry thoroughly. Rewipe everything with water, and then dry thoroughly again. Be careful with chlorine solution on bluesteel guns, because chlorine solution can cause rust if not properly wiped off the metal portions of your guns.
Take Care of Moisture Inside Safe
You can use a dry rod, which is a small, safe heater that uses heat to create an air current that keeps moisture from settling on the guns. Therefore, you keep mold from growing on the guns and the insides of your safe. You can find dry rods at most gun stores; go to a store that you trust, preferably one that sells gun safes. Place the dry rod in the lower portion of your gun safe. Because it runs on electricity, a plug version is best if your safe has an internal electrical plug or hole for a cord. There are battery versions available if your gun safe is not cord- or plug-accessible. Using a dry rod should keep the moisture level low enough in your safe to retard or totally eliminate mold growth.
Minimize Room Humidity
Too much moisture in the air in the room the safe is contained in can also be a major reason for mold growth. If you are keeping your guns and safe in a basement or a house with high humidity, the room containing the gun safe should be just about 45 percent humidity. You can use a desiccant dryer in the gun safe room. Desiccant dryers purge water from humid air by passing it through a compound that easily absorbs moisture. Common desiccants used in desiccant dryers are calcium sulfate, silica gel and alumina. You can also use a common household air dehumidifier, which removes humidity from the air by cooling the air and reducing its ability to retain moisture. With most dehumidifiers, you can typically set how much or little moisture you want in the air, allowing you to keep the gun room at a consistent 45 percent humidity.