Gentle Cleaning Methods
- 1Handle rare coins carefully. Handle rare or unidentified silver coins as little as possible. Hold them by the edge only, not the face, and ideally wear lint-free cotton gloves. Even if the coin looks dirty or damaged to you, a collector may pay more if you leave it in its natural state and avoid further damage.
2Soak the coins in warm distilled water and soap. Add a few drops of mild soap (not detergent) to a glass of warm distilled water. Put the coins in gently and leave them to soak, turning them over every few hours. This is the only guaranteed safe way to clean silver-plated coins (though pure silver is a little hardier).
- Store rare coins in Mylar plastic coin flips, or ask a coin dealer for alternatives. PVC coin flips can damage your coins.
3Replace the water daily. The next day, if the coins are still grimy, replace the water with fresh distilled water and soap. Repeat daily until the coins are clean (but still have their toning).4Dry carefully. Pat the coins dry with a paper towel, or leave them on an absorbent cloth to air dry. Rubbing the coins is very risky, since it can scratch through the toning. Careful brushing with a soft-bristled toothbrush is usually safe, but work slowly and gently with valuable coins. The goal is to dislodge loose dirt, not to brush the coin’s surface directly.5Wet and freeze the coins. If the coins are still dirty, soak them in distilled water again. Transfer the wet coins to a plastic container in the freezer. The water will expand as it freezes, hopefully breaking off some of the dirt from underneath. Gently pat or brush off dirt once frozen. In most cases, you will need to repeat the soaking and freezing several times.6Remove heavy dirt buildup with long-term oil soaks. If the coins are covered in mud or dirt and do not respond to the methods above, soak them in mineral oil or olive oil. Mineral oil should never harm your coin, but must be washed off with acetone afterward. Olive oil will also work, but there is a slight chance of damage. Either one can take months to clean extra-dirty coins. For best results, prop the coins up on a piece of plastic so both sides are exposed to the oil.
- Tap water contains chlorine that can lead to discoloration.
- Tarnish (a thin layer of grey, black, or iridescence also called “toning”) is not the same as dirt. If the coin is rare, toning may even be a desirable feature that raises the coin’s value.
7Check on the oil every couple weeks. Rinse the coins in warm, soapy water to remove the oil. If the dirt doesn’t come off with it, leave the coins to soak longer. If using olive oil, replace it whenever it turns dark green. Once the coins are clean, rinse them in warm, soapy water. If you used mineral oil, wipe them with a swab dipped in pure acetone.8Use an ultrasonic cleaning machine. These machines vibrate the coin rapidly to dislodge dirt. Small machines for home use are safe for coin cleaning, but will only remove soft, minor dirt buildup. Large, professional machines are more effective, but must be used carefully. For best results, suspend a cup from a string so it sits halfway submerged in the machine’s bath, without touching the base. Fill the cup with slightly soapy distilled water and hang the coin suspended in this solution. Fill the main bath with pure distilled water, run the machine for only a few minutes, brush the coin, and repeat.
- Cheap, non-virgin olive oil works better than virgin or extra-virgin, since it is more acidic.
- If the coins are not valuable as collector’s items, you can skip to the harsh cleaning methods instead to save time. If the coins are rare or unidentified and you don’t want to wait months, take them to a coin collector for advice.
- You can run the machine without the cup, but dirt or objects on the base of the pan will interfere with the pan’s vibration and shorten the machine’s lifespan.
Source: wikihow. com