Where does verdigris come from?

Discussion in 'Coin Chat' started by Siwash, Nov 27, 2011.

  1. Siwash

    Siwash Senior Member

    I had two brass tokens, in shiny shape, and over the course of the year, they dulled and now have greenish blotches on them.

    How does this come to pass? What happens to make this go?
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    GDJMSP Numismatist Moderator

    In a nutshell - improper storage.

    The green could be a couple of things. It might be PVC residue from PVC flips. Pretty much ever dealer there is sells his coins, tokens, and medals to you with it in a PVC flip. So if you don't take that flip and throw it away as soon as you get home and put the coin in a good coin holder - then you have screwed up.

    It could also be verdigris. Verdigris caused by a combination of things - impurities in the air and moisture in the air (humidity). So if you don't store your coins properly to limit air contact and humidity - then you have screwed up.

    Proper storage alleviates both PVC damage and verdigris. Thus the nutshell answer to your question.
  4. BadThad

    BadThad Calibrated for Lincolns

    Doug did a good job.

    Verdigris is mainly composed of copper salts. Only one thing is required for verdigris to form on copper: air

    If you have it and you want to essentially halt the progress, soak the coin in acetone to dehydrate it and immediately put it into an airtite holder.
  5. rickmp

    rickmp Frequently flatulent.

  6. mill rat41

    mill rat41 Member

    So PVC flips are still being used, knowing they are bad for coins? I recently bought a coin from a respected dealer - the flip was real flexible and smelled like a new shower curtain.
  7. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

    Yes, because they are cheaper and softer, so they will scratch or rub a coin less. If a dealer thinks enough of a coin that might deserve an air-tite (tm) holder, he will usually just have it slabbed. Generally, unless the environment is extremely bad, PVC acivity wouldn't be seen for several months at least, giving a person plenty of time to decide what to do. If reselling it, just leave it in the PVC, if good enough for slabbing, do it. If keeping it for a long time, acetone and proper storage.

  8. medoraman

    medoraman Supporter! Supporter

    Like Jim said, its fine for short term. Its said PVC causes damage since its much superior in every other way for flips. They don't crack, scratch a coin as much, and just all around better. Unfortunately long term they damage a coin, so dealers use them but they are not recommended to keep them there a long time.

    GDJMSP Numismatist Moderator

    You as an informed collector are supposed to know this and you are also supposed to know that you have to remove the coins from the dealer's flips and place them in a quality coin holder.

    Now I'll grant you, you are definitely not alone. There are a lot of collectors out there who do NOT know this. But then that's why I post a lot of the things I do.
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