Your metal detector is safely stored away and now it's time to comb through the bag or box of today's finds. If you've had any luck, there may be some real prizes in there: an old coin or two, a jewelry chain, even a gold medal or button. At least that's what every metal detectorist hopes for. So if you do make a nice find, what should you do next? The answer depends on what you've detected.
Don't Clean Valuables!
If you've discovered a coin or other object that is in any way valuable, the best thing to do is not to clean it. Cleaning will actually decrease the value of the object. If you suspect you've found something of value, first try to identify it via a book or website on memorabilia or coin and treasure hunting. (If you have an old uncle who used to be a pirate, so much the better.) That failing, visit a coin dealer or jeweler to get a professional opinion. Only clean your metal detector finds if doing so won't diminish their value!
Gold items can be effectively cleaned by letting them sit for about a minute in a lidded jar that contains one part ammonia to six parts water. After removal, polish the gold with a soft cloth. An alternative to ammonia, which can damage gold with excessive use, is to use a metal polish or jewelry cleaner.
Silver is often relatively easy to clean compared with other treasures found by metal detectors. Start by using a soft toothbrush dipped into a mix of warm water and soap. Some metal detectorists prefer to use a toothbrush and baking soda.
Stained or encrusted silver may require more aggressive cleaning methods. Electrolysis is an effective way to clean silver, but it's a little complicated for part-time detectorists. Try using a silver cream or soaking the item in vinegar to get rid of difficult stains.
Copper and Nickel
Tumbling (see below) is a popular way of cleaning pennies or nickel coins. Soaking coins overnight in a covered container of vinegar and then rinsing them is very effective. However, it can leave coins looking a little dull.
Metal detectorists who find a lot of old coins might want to invest in a rock tumbler. To use the tumbler for cleaning, put in the dirty coins with some small pebbles and sand. Then fill it with water and a small amount of detergent. Let the tumbler work for several hours, then empty it and replace the water. Let the tumbler work for several more hours (or even overnight, if necessary) and then pour its contents over a sieve. Rinse the coins and set them out to dry. It's best to tumble silver, copper, and nickel coins separately.