How to clean old coins

How to clean old coinsHow to clean old coins

A common question amongst coin collectors, especially younger collectors is how to clean old coins. If you have been given, for example, an old Victorian penny you might be disappointed to see that it's a rather dull dark brown as opposed to a new looking bright shiny copper colour and you could be tempted to want to shine it up so it looks like new in your coin collection.

How to clean old coins if they might be valuable

Well, the simple answer to how to clean old coins is that if the coin is remotely rare or remotely collectable then you shouldn't clean it at all. Coins develop a surface covering called patina which dulls the coin over time though it doesn't necessarily mean that the detail on the coin isn't still well defined or that the coin has become less desirable by collectors. It is caused by exposure to oxygen (or 'oxidation'). Coin collectors expect to see some patina on old coins  and it actually adds to the appeal of good quality rare coins. It's quite a subtle thing patination but to the untrained eye or the younger collector, patina is boring and hides the shininess.

If you have found a coin out in mud, or in a river (perhaps by using a metal detector) and it is encrusted with dirt then you may, of course, try cleaning it under a tap being careful not to rub it or scratch it. If it is really dirty then you might want to try using a very soft brush being careful not to scratch it. If you think it might be really old or important and you're not confident you know how to clean old coins, you should get in touch with a local historical society or museum and ask their advice before you set upon it.

Another method used to clean encrusted coins is electrolysis whereby a current is passed over the coin to loosen any debris (and also the patina). If you do a search around you should be able to find ideas about how to do this, or you might be able to find someone local to you who could treat your coin in this manner. The advantage of electrolysis is that it isn't abrasive and it's FAST! There is less likelihood of any accidental damage though damage can still occur because on very old coins, it might be the patina that is holding the coin together! If a collectable rare coin is cleaned using chemicals then it will almost always lose value because collectors won't want a coin that has been artificially brightened up. Therefore the first thing to do before cleaning anything is to check the value of the coin to make sure you're not effectively destroying something of worth. You can do this by looking at the books we mentioned previously or by searching through the for sale listings on the right of this page to see if you can locate your coin.

If you decide that you really do want to clean a coin and you don't care about the fact that it will lose value then there are various acidic chemicals that you can soak it in which should bring it up in a lovely shine. Common chemicals that are good for cleaning coins are:

  • Vinegar
  • Cola (any type)
  • Tomato ketchup
  • Olive Oil

All will effectively burn off the top layer of patination and leave you with a shiny coin. For younger coin collectors in particular, shiney coins can be a fun way to get them interested, just don't leave them in reach of both your prized collection and a bottle of tomato sauce or you could be in for a shock if they decode to "help" you out one day by carrying out a surprise coin clean!

You should never ever use the above chemicals on a remotely rare coin. If you have what you think might be a rare coin always get advice from a coin dealer before you do anything and never ever be tempted to clean mint, uncirculated coins, or proof coins which are struck with a mirror like finish.

We hope you've found this article useful and that you now know how to clean old coins (and when NOT to clean them!)

6 Comments on "How to clean old coins"

  1. dear sirs I have a large collection of old coins in Afghanistan and can bring to the United Kingdom. it starts from 1800 to 1950s. and might be some old from USA, EUROPE and ASIA. kindly reply me if you want to buy.

  2. Being a younger collector I am attracted to shiny coins. The methods given above are “destructive” in that you will lose silver. A trick my chemistry teacher dad taught me is doing a chemical exchange bath.

    Put you silver, works for tea sets etc also, into a warm water bath with aluminium foil and soda crystals (normally sold in washing detergent isle). You can alter the pace of reaction by added hot water and if its isn’t working at all you need to add more soda crystals.

    What is happening is that, because aluminium is extremely reactive, the foil “steals” sulfides and oxides from silver’s surface. The soda crystals just allow the atoms to move through the water. The silver will be restored to just silver and the majority of the black tarnish will magically appear on the foil.

    The reason why you should always use this method first is that the original silver which was oxidied/sulphised is preserved and not removed (in fact it is transformed back to its original pre-tarnish state). Other methods basically take off the top layer, so you’re losing silver and obviously over time you will loose the detail of your coins.

  3. Thanks Oli – good advice there!

  4. Bob J. Valdez | February 20, 2015 at 9:05 pm |

    We are looking for a buyer gold coins, queen elizabeth,alfonso 13

  5. william steele | May 6, 2015 at 3:50 pm |

    I recently dug up an old silver coin in London. I can’t identify the king but the obverse looks exactly the same as shown on your web site under the title ‘ how to clean old coins. I would appreciate your help

  6. I have just found a napolining 111 emperor coin 1854

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