Posted 07/08/2009 08:07 am
I would say, and most collectors would agree, that you should never clean a coin, just because it looks "tarnished". On coins, "tarnish" is called "toning" and it's considered attractive; removing it will make a coin less desirable to most collectors.
They're your coins, of course; you're free to collect whatever you like, and do with them as you please. But be aware that most collectors will disagree with your opinion, and you (or your heirs) will pay the price later when they are sold; the coins will be worth much less than they should have been.
Never clean uncirculated coins. Cleaning them effectively causes wear equivalent to time in circulation, greatly reducing their value.
Never clean heavily circulated coins. They'll just look ugly and "un-natural". A heavily worn coin should look it's age, and is not going to be made to "look like new" by being cleaned - it will simply look like a cleaned coin.
There are, of course, exceptions to every rule. Examples of coins that you CAN clean are:
- coins covered in actual, physical dirt from being buried in the ground or coins that have been damaged in flood, fire etc.. You can use whatever happens to work to clean such coins, because whatever you do to them, they'll probably always look "cleaned". Begin with gentle treatments (distilled water, soapy water, olive oil, etc) then if that doesn't do the job, move on to more noxious things (electrolysis, assorted acids, ammonia, sodium hydroxide).
- coins that have been kept in nasty plastic coin albums where the pages or holders have all turned green, and covered the coins in sticky goo. Use acetone, alcohol, petrol or some such solvent to remove the sticky stuff. The coins will probably be damaged anyway, but if the goo is left there, even more damage will occur.
- coins with severe "contagious" corrosion. Copper and bronze coins are prone to "bronze disease", where a pale greenish powdery corrosion spot forms then, if conditions are good, slowly spreads over the surface until eventually the whole coin becomes a crumbly green mess. Aluminium and zinc coins can also develop such "cancers". This needs to be treated, often quite severely, to prevent further damage. The resulting coin will look cleaned and corroded, but further damage has been prevented.
- war medals. Nobody can persuade an old soldier that his war medals aren't supposed to be all nice and shiny, so we've given up trying.
They're your coins, of course; you're free to collect whatever you like, and do with them as you please. But be aware that most collectors will disagree with your opinion, and you (or your heirs) will pay the price later when they are sold; the coins will be worth much less than they should have been.
Never clean uncirculated coins. Cleaning them effectively causes wear equivalent to time in circulation, greatly reducing their value.
Never clean heavily circulated coins. They'll just look ugly and "un-natural". A heavily worn coin should look it's age, and is not going to be made to "look like new" by being cleaned - it will simply look like a cleaned coin.
There are, of course, exceptions to every rule. Examples of coins that you CAN clean are:
- coins covered in actual, physical dirt from being buried in the ground or coins that have been damaged in flood, fire etc.. You can use whatever happens to work to clean such coins, because whatever you do to them, they'll probably always look "cleaned". Begin with gentle treatments (distilled water, soapy water, olive oil, etc) then if that doesn't do the job, move on to more noxious things (electrolysis, assorted acids, ammonia, sodium hydroxide).
- coins that have been kept in nasty plastic coin albums where the pages or holders have all turned green, and covered the coins in sticky goo. Use acetone, alcohol, petrol or some such solvent to remove the sticky stuff. The coins will probably be damaged anyway, but if the goo is left there, even more damage will occur.
- coins with severe "contagious" corrosion. Copper and bronze coins are prone to "bronze disease", where a pale greenish powdery corrosion spot forms then, if conditions are good, slowly spreads over the surface until eventually the whole coin becomes a crumbly green mess. Aluminium and zinc coins can also develop such "cancers". This needs to be treated, often quite severely, to prevent further damage. The resulting coin will look cleaned and corroded, but further damage has been prevented.
- war medals. Nobody can persuade an old soldier that his war medals aren't supposed to be all nice and shiny, so we've given up trying.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
