Cleaning Coins


The first thing most say is Do Not Clean Coins.
Well there is cleaning & Preservation. Both are looked at differently.
Preservation: If left as is, the condition of the coin would deteriorate further. A simple example of this is Bronze disease. If such coins are not cleaned, then they are spoilt further. Similarly there could some acid or other corrosive substance that needs to be removed. Generally if the guys in the Museum do this, its called preservation.
Cleaning: The same thing done by ordinary individuals is called cleaning.
Harsh Cleaning: Coins cleaned badly with the intention of making them shinning. Often doing long term damage.

Although it’s normally recommended that coins should not be cleaned, this article gives some of the ways in which coins can be cleaned and maintained. It is generally true that improper cleaning of the coin would reduce the value of the coin than if it were not cleaned; however there are times if the coins are not cleaned, they would get damaged further.
This article mainly focuses on cleaning of the coins using every day available material is does not explore professional cleaning of high value or very rare coins.
Before trying any of the methods it is recommended that one start of with coins that are not rare to check out the effectiveness of the method. Even if the method is found effective, one should watch the coin for a good amount of time say around month or more to check if there are any long term negative effects of using a particular method. Reader description is advised while trying out the methods described in the article.

Eraser
The easiest way of cleaning a coin is using a good quality eraser [generally used to clean pencil writings] that would be available in home or in any stationary store.
Method: Holding the coin in hand, rub the coin vigorously. To make it easier, one can press the coin firmly against a hard surface [note ideally the surface the coin is pressed against should be wood or plastic chopping board]. The rubbing action removes the loose dirt stuck; the action also generates heat and makes the coin shinier.

Advantages:
  • It’s relatively easy to do this at home. Plus on most of the coins it’s safe.
  • Removes most of dust

Caution:
  • If the surface against which it’s pressed is not clean, the coin can get dirtier. Avoid using paper, especially a newspaper or magazine. As the print on them can get transferred on to the coins.
  • At times on certain coins [mostly Nickel-Brass] it would also remove a layer of the polish and make the coin more dull
  • Not very effective on Aluminum coins
  • If the coin has heavy oil soiling / sticky surface, it will be less effective
  • More than required rubbing will leave rubber marks on the coin
  •  If the coin is not flat, it would clean unevenly and leave stripes of shining and dull finish.

Effectiveness:
  • Best for Cupro Nickel Coins and Nickel Coins
  • Average results for Silver and Stainless Steel Coins
  • Lest for Aluminum-Magnesium Coins

Water
The other easy way is to use regular water or Better to use distilled water. Note that it has to be good water and not hardened bore well water. It’s best if mineral water is used.
Method: Dip the coin in lukewarm water for 5 to 10 minutes or distilled water for few days. Post this remove the coin and rub vigorously with a soft cotton cloth. This would remove most of the soiling. At times mild soap may also be used. If soap is used, make sure that the coin is rinsed couple of times.

Advantages:
  • It’s relatively easy to do this at home. Plus on most of the coins it’s safe
  • Removes most of dust and staining

Caution:
  • If the water used is hard water, it would react with the metal and possibly corrode it
  • Does not remove stubborn stains
  • Not very effective on Aluminum coins

Effectiveness:
  • Best for Cupro Nickel, Nickel, Silver and Stainless Steel Coins
  • Lest for Aluminum-Magnesium Coins

Lime or Ketchup
The other easy way is to use lime juice or Ketchup [the acidity of tomato with salt and vinegar makes it a good cleaner]
Method: Dip the coin in lime juice for couple of hours in line juice or about 10 minutes in ketchup. The slight acidic lime will remove lot of grime and dirt. Post this rinse the coin with good water and rub vigorously with a soft cotton cloth. This would remove most of the soiling.

Advantages:
  • It’s relatively easy to do this at home. Plus on most of the coins it’s safe
  • Removes most of dust and oil staining
Caution:
  • If not rinsed properly, it can leave the acid with can react with the metal
  • Not very effective on Aluminum coins
Effectiveness:
  •  Best for Cupro Nickel, Nickel, Silver and Stainless Steel Coins
  • Lest for Aluminum-Magnesium Coins









4 comments:

  1. Hi, please let me know if lemon juice is damaging to silver coins? I have got good results for cleaning silver coins with lemon juice, however not sure if it damages the coins. Doesn't look like it to the naked eye, however I now have some valuable silver coins that could do with a cleaning, however I'm afraid to damage them with lemon juice... Any tips?

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    Replies
    1. that was a lot of 'howevers'! :)

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    2. It depends on the method. If you follow as in article, not much of damage. However if you use concentrate or keep for longer period or don't rinse with distilled water there can be damage. Note at times it takes few months / years for damage to be visible

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    3. thanks for the reply. since i think its value is over $300 for this particular coin, i will refrain from cleaning it!

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