Should you clean a coin? When should you clean a coin? How should you clean a coin?
In the coin world you will always hear dealers saying “No, you should never clean coins”. The main reason for this is to stop people making mistakes, especially with old, rare or valuable coins. If coins were never cleaned, many of the ancient coins you would see on Coins-auctioned.com and elsewhere would be lumps of dirt. Many ancient coins come from the ground and need washing before they can even be identified as a coin. Even third party grading services offer coin conservation services, which is essentially cleaning.
Firstly, DO NOT clean rare or valuable coins, always seek professional advice. It’s possible to remove almost all of a coin's value with careless cleaning.
It’s important to realise that there are different levels of cleaning, some are regarded as common practice, others are not, and some should never happen.
Washing. Simply washing, and rinsing, a coin in clean water. This won’t remove stains or tarnish, but will remove the dirt from most detectorists or archaeological finds.
Mechanical cleaners such as ultrasonic cleaners. These should be used with the utmost care. They are very good for removing surface dirt and to an extent, some corrosion on base metal coins, but it is very easy to take the process too far and damage the coins appearance.
Dipping. This can be anything from giving a coin a quick dip in acetone to remove oils and deposits (including residues from vinyl coin holders), through specialist coin cleaners, to full on toxic chemicals and acids. Some of these chemicals can irreversibly change the appearance of a coin and must be used with care.
Polishing. This is using any abrasive to remove material from the surface or add “shine”. If you’re using coins for a craft project, fine, but for a collector, this is a definite NO. Abrasives damage a coin's surface, remove patina and add details of their own, which is not what a collector wants to see.
If after cleaning you have ancient base metal coins that have a reddish or brownish powdery surface, zinc coins that aren’t showing the details nicely you can apply a thin layer of a microcrystalline wax such as Renaissance Wax. This treatment is reversible and can be removed at any time, but can help to protect some coins.
One thing that is very important is that you record whatever has been done to a coin in case you ever want to sell or gift it to another collector so they know what they have.
Again, DO NOT clean rare or valuable coins. Most collectors don’t, or rarely clean coins as it can greatly reduce value. If you have some smaller value coins like Dimes or Pennies, then this article is for you.
Patina is the thin layer of tarnish, or toning, that develops on a coin over many years and many coin collectors appreciate this as sometimes it can be quite beautiful. When grading coins, patina can be a factor.
Patina can be greenish copper- type colours or brownish hues on copper and bronze based coins, or rainbow to grey to black on silver coins. It’s best not to clean patina off rare coins as the value can be reduced. The vast majority of coins do not increase in value after cleaning, but if you have some old coins you wish to clean, try these steps.
We all have coins in our drawers which are dirty and even have a certain smell, fortunately most of these are lower value coinage and you can enjoy cleaning these as most are just pocket change.
Rinse the coins under running water. Hold the coins by their edges.
Distilled water is best as most water is now treated with fluoride and this can cause different chemical reactions with some coins as many are made from a combination of different metals.
Soak the coins in vinegar for around a minute.
Rinse in running warm tap water and fully rinse the coins.
Air dry instead of using a drying cloth.
Another alternative is to pat or blot dry with absorbent paper, only dabbing , don’t rub or wipe.
If it is still dirty you can use a soft brush, such as a child’s toothbrush, for caked-on dirt. Following the drying methods as above.
Complete the same process as outlined above and soak for 5 minutes in lemon juice help to keep the coin shiny.
Canadian coins that are 99.99% pure silver do have a problem with Milk spots. Milky spots are a milky white substance that appears on the surface of Royal Canadian Mint Coins. This is due to their mintage process and microscopic silver chloride debris that causes these marks.
Perth Mint coins do not have these issues as they updated their equipment and it is very rare to find an Australian silver coin with these milk spots, but the Royal Canadian Mint (RCM) still has this problem. The Royal Canadian Mint had stated that their coins are not collector coins but bullion, so it is not a problem they intend to address. They do not consider bullion as circulating coin or for collectors. So be aware when buying RCM coins that they may have milks spots on them at some stage.
Silver Maple Leaf Coins seem to be the most affected silver bullion. It seems once over .999 purity to go to 99.99 % pure silver is very complicated. Some people use pencil rubbers to clean or silver cleaning cloth for silver jewelry. Best to keep RCM coinage in capsules but some NGC capsules have developed spots after being sealed.
Most countries mintage of large volumes of copper coins that were low denominations but some of the deigns were of high standard so its easy to understand why people want to clean these copper coinages. Britain’s one penny displayed beautiful design, Britannia seated facing right, wearing a helmet, holding a trident, hand resting on a shield and most famous copper coinage is the shipwreck 1808 Admiral Gardner Shipwreck coins popular with coin dealers worldwide. European copper coinage includes 1853-1856 (five) 5 cents with beautiful Roman style design. The reasons why people want to clean copper coins is to remove the Copper oxide, a greenish tarnish common on these copper items.
Place a table spoon of table salt in small container.
Add white vinegar to moisten salt.
Apply paste to coins, some may need to be soaked for 5 minutes.
The effect is immediate. You can use ketchup, tomato paste or lemon juice as they are also acidic.
Rinse with warm water and air dry.
Do not use this method on valuable coins and be careful not to get any in your eyes.
Bronze coins can also be cleaned in soapy water or olive oil but not virgin olive oil as it might tarnish the metal.
Soak the coins in warm soapy water only. Distilled water is best.
Air dry the gold coins only. Gold is too valuable to risk damage.
Some people do use a gold cleaning cloth that is used for gold jewelry.
First decide, do you really want clean a ancient artifacts? Some ancient coinage when found can be completely covered in solidified clay or dirt, then commercial coin dealers soak them in liquid soap on vibrating machine which cleans and softens the outer material leaving coinage and platina on coin as it had been before. If you stil think you want to clean your ancient coin then,
Soak in soapy distilled water but never use lemon juice or vinegar on Bronze coinage.
Baking Soda can help clean the coins when they are soaked in soapy water.
Try an acid product but only if you are sure of the coin type.
If you’re not sure of the type of coin use hot sauce like Tabasco or taco sauce, Coke or coke products can be used.
Store your coins in an airtight container or better still a coin capsule.
Use a commercial coin cleaners if you are uncertain.
Do not use abrasives on a coin as they can scratch easily.
Do not use household cleaners on your coins.
Do not use silver dip cleaners from home or silver polish.
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