If you own one or more challenge coins, chances are good that they’re among your prized possessions. If one was given to commemorate your military service or service to another group, such as a local fire department or police force, it’s likely tied to precious memories, and for collectors, challenge coins hold considerable aesthetic and monetary value. Regardless of why you own challenge coins, though, it’s important to store them safely and keep them clean, but many coin owners aren’t sure what to do.

The first thing to remember is to always store challenge coins in places with low humidity. Because they are made of metals, challenge coins are susceptible to corrosion in the presence of humidity, so your coins will ideally be stored in an area with a relative humidity of thirty percent or below. Challenge coins should also be stored individually in non-vinyl plastic holders or paper envelopes; both can be used for storage without damaging coins. Be sure to never store your coins in wooden cabinets or drawers, as wood, particularly oak, can give off acidic vapors which may corrode coins.

It’s also important to properly clean challenge coins on a regular basis. For routine cleanings, your coins can be soaked in lukewarm distilled water for about twenty-four hours, with each coin submerged separately so no two are touching. If there is grease or excess gunk on any of your coins, you can mix warm water with dish soap, submerge the coin and scrub it gently with a toothbrush. In extreme cases you may want to soak your coins in a soap solution for extended periods of time, but if you do so, make sure you’re using a soap with no acidity.

There are also several other options to clean particularly dirty challenge coins. One method is to use olive oil to loosen dirt or other substances stuck to coins; to do so, soak each soiled coin in olive oil for approximately a week, changing the oil if it darkens visibly. Yet another option is to use isopropyl alcohol, which is a mildly acidic substance commonly used to dissolve dirt or other unwanted particles. To make an isopropyl alcohol bath safe for the cleaning of challenge coins, mix it with equal parts water, and submerge each coin for about two hours before removing them and rinsing thoroughly with water.

Overall, constant vigilance is the key to keeping challenge coins in good condition. Once you’ve ensured that you’re storing your coins properly, check on them regularly and clean them carefully when needed. As long as you follow these simple rules and are gentle when handling coins, your challenge coin collection will be in good hands.