One important area of collecting coins is to ensure that coins are to be kept in good condition and ensure that they are stored in right environment. At times, this can be difficult due to heat and humidity which often causes verdigris on copper coins to spread like wild fire. Poor storage and choice of material such as PVC flips can add to the trouble.
|Country||Era||Coinage||No. of coins||Last updated|
|China - East Hopei||1937||East Hopei circulated coinage||1||10 March 2015|
|China - Manchukuo||1933 - 1945||Manchukuo circulated coinage||TBA|
|China - Soviet China||1933, 1960s||China - Soviet including restrikes||2||10 March 2015|
|China - Uighurstan||1933||Uighurstan circulated coinage||3||10 March 2015|
|Korea||1888 - 1910||Empire coinage||TBA|
|Sadagura||1771 - 1774, 1795||Sadagura gun metal circulated coinage||12||10 March 2015|
|Total number of coins preserved / restored||18|
More to come...
Preservation is a mean to ensure coins are free from contaminants which may enhance appearance and restore its condition. Unlike cleaning, preservation avoids using harsh chemicals or methods which often result in stripped colour surface or scratches. In simple terms, I like to compare cleaning oneself with a sponge against wire scrub. Needless to say, you would know which one hurts more.
I admit - there are times when I have improperly stored coins and have "accidently" let them tarnish / corrode due to my poor insight. There are also times when I intentionally bought coins that are loaded with verdigris simply because I knew they are scarce and am certain that I would not see another example for a long time or otherwise unaffordable. There are a couple of examples that I have not seen for more than a decade!
These are my choices of preservation. There are plenty of other sites out there that offer their advices. My word of advice is, always try on cheaper coins first and build confidence. Allow room for trial and error.
Acetone: Perfect for many coins especially if there is PVC residue. Not effective against verdigris. Use for copper coins should be tested - I had some negative experience as there is a possibility that contaminants on a copper coin re-deposit on other part of the same coin, causing it to look hazy. Note - highly flammable and dissolves a lot of plastics. Use acetone in a ceramic or glass container. Do not inhale the vapour and use in a well ventilated area.
Verdicare: Probably the best choice for all coins including copper. Cost and time wise, this is the most expensive and works the most efficient. It suits well for copper, nickel coins and many other metals. This removes most verdigris without stripping much patina. Gun metal and some alloy coins may prove to be a challenge from my experience, possibly due to the complex alloy content. Obviously this is not a magic potion - if a coin is too heavily damaged with verdigris, it's probably too far gone for help. Obviously avoid problem coins in the first place but there are just some rare coins that you want so badly or you got it for a steal. ALWAYS read instructions before use.
Extra virgin olive oil: This used to be my choice of preserving copper coins before Verdicare was commercially available. This has its ups and downs. Cost wise, this is cheap. However it is not foolproof and has a higher rate of failure.
There are other products such as Blue Ribbon, dipping chemicals, baking powder and such however I did not go around testing them.
10 March 2015