Difference between revisions of "Clean Silver Coins"

#Handle 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.<ref name="rf1">http://www.numismaster.com/ta/inside_numis.jsp?page=how-to-handle-clean-coins</ref>

#Soak the coins in warm distilled water and soap. Add a few drops of mild soap (not detergent) to a glass of warm distilled water.<ref name="rf1" /> 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).<ref name="rf2">http://romancoin.info/complete_guide_to_uncleaned_ancient_coins.htm</ref>

#*Tap water contains chlorine that can lead to discoloration.<ref name="rf1" />

#*Tarnish (a thin layer of grey, black, or iridescence also called "toning") is not the same as dirt.<ref name="rf3">http://www.forumancientcoins.com/Articles/Uncleaned_Ancient_Coins.html</ref> If the coin is rare, toning may even be a desirable feature that raises the coin's value.<ref name="rf1" />

#Replace 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).<ref name="rf2" />

#Dry 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.<ref name="rf2" /> Careful brushing with a soft-bristled toothbrush is usually safe, but work slowly and gently with valuable coins.<ref name="rf4">http://www.kersh.com/coin_cleaning.php</ref> The goal is to dislodge loose dirt, not to brush the coin's surface directly.

#Wet 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.<ref name="rf5">http://www.metaldetectingworld.com/cleaning_coin_p6_mechanical.shtml</ref>

#Remove 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.<ref name="rf5" /> 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.

#*Cheap, non-virgin olive oil works better than virgin or extra-virgin, since it is more acidic.<ref name="rf6">http://www.rhyniechert.com/coinscleaning.html</ref>

#Check 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.<ref name="rf6" /> 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.

#Use 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.<ref name="rf7">http://www.metaldetectingworld.com/cleaning_coin_p14_ultrasonics.shtml</ref>

#*An even gold, grey, or iridescent tarnish (toning) is desirable and increases the coin's value.<ref name="rf8">https://www.ngccoin.com/news/article/2831/dipping/</ref>

#Pick dirt out of small crevices. After washing the coin in soapy water, you may still see dark areas outlining letters or detailed images. Wash again and pick away this dirt slowly and carefully using a toothpick or bamboo skewer. Take care not to scratch the coin, since the pick can scratch away the tarnish.<ref name="rf2" />

#Rub with silver polish. Silver polishes clean metal using acid and abrasives, both of which eat away a small layer of metal. This is an easy way to brighten non-collectible coins, but will almost certainly damage the value of collectibles:<ref name="rf9">http://www.silverinvestingsimplified.com/Cleaning-Silver-Coins.html</ref>

#Wipe with a paste of baking soda and water. This cheaper alternative to silver polish also abrades the silver coin, causing scratches that will be visible under a magnifying glass. Minimize damage by using distilled water and mixing in just a little baking soda to make a watery paste. Dip the entire coin the paste, rub between your fingers for a minute, then rinse with water. Repeat two or three times if necessary. Pat dry.<ref name="rf9" />

#Remove hard deposits with ammonium. A thick buildup on ancient coins is likely "horn silver" (silver chloride). This may be worth removing, especially if it prevents identification. Submerge the coin in a 10% ammonia solution in a tightly sealed container. Remove it after a few minutes, rinse immediately in water, then brush with a soft toothbrush. Repeat as needed.<ref name="rf10">http://www.colchestertreasurehunting.co.uk/c/cleaning.htm</ref>

#*'''Warning:''' ammonia liquid and fumes are corrosive. Wear neoprene gloves and work in a ventilated area.<ref name="rf11">https://www.osha.gov/SLTC/etools/ammonia_refrigeration/safety/</ref>

#*Soak the coin in a 50/50 mix of distilled water and lemon juice for one hour.<ref name="rf12">http://ancientcoinsforeducation.org/content/view/66/90/</ref>

#*Soak the coin in 1 tsp (5 mL) lemon juice mixed into 1.5 cups (360 mL) olive oil. Warm this in a heat safe container inside a water bath, but keep it below boiling.<ref name="rf13">http://www.metaldetectingworld.com/cleaning_coin_p13_ammonia.shtml</ref>

#*"Dipping" treatments can return a coin to a frosty white silver appearance, which some collectors value. However, this is an extremely risky procedure that can cause blemishes to appear. Hiring a professional is strongly recommended, but you can buy a dipping solution to use at home.<ref name="rf8" />

*If your coin is coated in lacquer or covered in a slimy green substance (a reaction to PVC in certain plastics), remove them with pure acetone. Wipe off slime with a cotton swab dipped in the acetone. Remove lacquer by soaking the coin in acetone in a non-plastic container. Work in a ventilated area to protect against fumes, and keep the acetone away from fire and heat.<ref name="rf14">https://www.buysilver.org/how-to-clean-coins/</ref> If the coin is valuable, take it to a professional instead.<ref name="rf15">https://coins.thefuntimesguide.com/cleaning_coins/</ref>

*Uncirculated and well-preserved "proof" coins should have a bright, silver surface with no tarnish. Do not clean or handle these, since the lack of scratches and damage makes them valuable. Dust them with a squeeze bulb of air, not by rubbing them.<ref name="rf16">http://www.mycoincollecting.com/collecting/cleaning-coins.html</ref>

*Heavily corroded coins are usually too damaged to be worth saving, even after your remove the corrosion.<ref name="rf1" />