Need some coin crud education - Green stuff?

Discussion in 'Coin Chat' started by Jeepfreak81, Jan 17, 2022.

  1. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Hey all,

    So I'm looking to educate myself further on the types of issues we may encounter with coins. The coin below is one I scored from the reject tray of a coinstar machine and it's not worth much at all. This makes it a prime candidate for experimenting with crud removal if possible.

    What I'm wondering is what am I looking at here? The green stuff is what I'm referencing, is this PVC residue? It currently sits in a mylar 2x2 but who knows where it came from.

    Or is this some other type of crud? What would be the preferred method or course of action for this coin, and what if it were worth a reasonable amount, would the course of action be the same?

    I know OF using distilled water, xylene, or acetone but don't really know the instances to use it or not and how long to soak, etc.

    Mostly just trying to educate myself and perhaps experiment a bit. I've casually collected coins for a long time but never really learned much about stuff like this.

    THA-001_Obverse.jpg THA-001_Reverse.jpg
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  3. John Burgess

    John Burgess Well-Known Member

    first things first, and that's knowing what metal or alloy you are dealing with.
    After that distilled water or Acetone is relatively harmless. it's 7 pH in both cases, just change your (solvent) cleaning fluid, whether acetone or distilled water when it's dirty, and rinse with fresh solvent so no deposits get left behind.
    so, your coin is 1 Thai Baht and it's a copper nickel composition.

    The one thing to remember is you want to stay as close to a neutral 7 pH as you can and when you wander from 7, you don't wander far, too acid or too alkaline will cause damage to the coin in either case.

    Most people use distilled water or acetone to remove surface contaminants before storing their coins, it does nothing to toning, and may or may not work on various adhesives, and won't damage the coin either (except acetone can break down given the right conditions, of sunlight and water. a fragment of the molecule can become acetic acid, The acetic acid may gradually corrode any copper that stays in contact with the acetone mixture. if it breaks down. the acid will react with the copper and create a metal salt (Cupric sulfate possibly? I'm not a chemist by any stretch of the imagination, so I might have it wrong)
    BUT, It's avoidable, by changing your cleaning solution regularly though, and using fresh, uncontaminated acetone.

    this isn't going to change the surfaces, it might dissolve organic compounds or minerals deposited on the coins surface into the solvent, that's about it, but you don't want to be cheap and keep reusing the same acetone over and over and never changing it out or mix water with it, or leave it in the sun to break down.

    I do recommend practicing on coins that are worthless, in case bad results happen. I also recommend making SURE the coin is about worthless before proceeding on your first shot at it.

    GDJMSP Numismatist Moderator

    Maybe, maybe not. There's no way to tell for certain just by looking at it. But if it is, acetone will take it off.

    I've explained the proper steps in this thread, just follow the directions -
  5. Mountain Man

    Mountain Man Supporter! Supporter

    You are correct in your statements about it being a good coin to experiment on, so please let us know your results and how you got it, if you chose to work on it. We could all benefit from your learning experience.
    Jeepfreak81 likes this.
  6. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Thanks for the replies, great info.

    Headed to read through this next, thanks!

    Yes I think I'm going to give it a go after a bit more reading. No huge loss if it doesn't come out well, and either way it will be a good learning experiment.
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  7. mbogoman

    mbogoman Member

    I can't imagine why a near worthless Thai baht coin would have spent any time in a PVC holder - the holder would be worth more than the coin. Since the coin is a copper alloy, it is far more likely that the green stuff is verdigris. If the acetone bath doesn't work, try one of the "verdi-care" type products on the market.
  8. Jeepfreak81

    Jeepfreak81 Well-Known Member

    While I'm not entirely in disagreement about the PVC flip - I put this worthless Thai baht coin in a 2x2. Why? because I like it and it makes it easy for me to add to a binder.

    I agree though, I doubt that it is PVC residue. I'm not versed in verdigris other than to know it exists and attacks copper. So that's a good point and perhaps seems I'm experimenting, that will be my next step.

    EDIT - Decided to toss it back in til tomorrow evening for the sake of science, lol. So I'll take a couple more pictures tomorrow night and we'll see if it had any effect on whatever the heck the green stuff is.

    In fact - Here is the result of having soaked it in Acetone for 30 minutes plus. Aside from the fact my lighting is a bit different than the original photos, the coin is largely unchanged. I should also note the original photos were taken with the coin in a 2x2, these new ones were not.

    Last edited: Jan 17, 2022
  9. Jeepfreak81

    Jeepfreak81 Well-Known Member

    So while my coin soaks in his relaxing acetone bath with a glass of wine, playing barry manilow, I thought I'd explore the option of trying xylene next if there's no improvement with the acetone.

    Two things. First - what can I expect xylene to remove that acetone won't? With a basic understanding of chemistry I know that Xylene is non-polar and works better for removing oils? Would this include oils from fingerprints for example? But in terms of my green mystery substance I'm wondering if xylene is worth trying should the acetone prove ineffective.

    Secondly - I figured I'd run out on my lunch break and grab some. Wrong! I checked Lowe's, HD, and Walmart in town here and nobody stocks it. So looks like if I want some I have to order it or travel and holey moley it's like double the cost or more of acetone. Yikes. If it's worth having, I'll get some but if it's negligible maybe I'll hold off. $22 for a can of it, I'm not sure my collection is even worth $22 (haha, I kid....sorta)
  10. GDJMSP

    GDJMSP Numismatist Moderator

    The single spot by the eye - that's verdigris. As for what's on the rev, that may be too but it's harder to tell based on the pics.

    Here's the thing about verdigris. I only know of one thing that will safely, stress safely, remove it and that's Verdi-Care. Unfortunately, none is available right now but the guy who makes it, a member of the forum known as @BadThad , hopes it won't be much longer until some is. That said, there are other things, methods, that many have done over the years to remove verdigris, but pretty all require mechanical efforts - meaning you have to physically scrape/scratch it off. Now @Insider has a method that seems to work pretty well but he knows more about and has more experience with the proper cleaning of coins than just about anybody - so that doesn't mean that just anybody else is gonna be able to do what he does.

    There's something else that needs to be said about verdigris, two somethings actually. The first would be that once verdigris has formed, the damage to the coin has already been done - and there's no changing that. Once done, damage is simply done.

    The second thing is that verdigris itself is not active, it's not gonna "crawl" across the coin and continue doing damage, it's simply what the copper in a coin has turned into as the copper corroded. Think of it as being "rust" on copper, just as rust is on iron or steel. The thing that is causing the corrosion is copper interacting with the air, and the moisture in the air - it's the very same mechanism that causes rust to form on iron or steel as it corrodes.

    The point here is that if you want to stop verdigris, there's no need to remove it, as I said the damage has already been done so removing it isn't really going to do anything except maybe improve the "looks" of the coin. But removing it also exposes the damage that has been done to the eye. So you trade one bad thing for another bad thing by removing it. To stop additional verdigris from forming what you have to do is control the air and the moisture in it from getting to the coin. And you do that with proper storage methods. Use proper storage methods and no more verdigris will form on the coin.

    So what are proper storage methods ? Well they've been written about and explained on this forum more times that I can even count. So simply do a search for them and read what you find. But here's the thing about proper storage methods - it seems a whole lot of people don't want to bother with them. They consider them to be too much trouble or too expensive. In other words they like doing things just the way they've always done them. But proper storage methods exist and it's not really difficult to utilize them, but for them to work, that's what ya gotta do - utilize them. And if you don't, then you, or rather your coins, very well may suffer the consequences.
  11. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Thanks for the reply! Last night I did some digging around on the forum about Verdigris and did in fact come across some stuff about Verdi-care. It's a shame it's not available at the moment, hopefully soon I guess.

    So I'm in full understanding that there will be damage underneath the verdigris for its very existence depends on such damage. I wasn't sure about if it would spread or not, so that's good information. This particular coin will most likely end up back in a 2x2 and in a binder but should I encounter this on a more expensive coin it's good to know I have some options to at least halt it.

    I've seen plenty of copper "turn green" as I've worked on plumbing and heating and copper electrical. Just have a look at the ground straps on an older car. I've heard people call it copper patina and in some cases it's desired for ornamentation.

    Good info here! However, aside from verdigris (which is likely the case for this particular coin) I'd still like to know in what cases Xylene would be of benefit before I order me a can at the cost of an ounce of silver.
  12. GDJMSP

    GDJMSP Numismatist Moderator

    Indeed it is. In point of fact I used to have very rich folks pay me a whole lot of money to make the very expensive copper roofs on their multi-million dollar houses I was building for them - turn green ! But - when copper turns green, including the copper pipes you were talking about, and those expensive copper roofs - it's all verdigris.

    The answer is found in the link I posted in post #3 of this thread. But short and sweet, you use xylene on things when acetone doesn't work, because it will take things off that acetone won't. And, you use xylene on copper coins because acetone can sometimes, stress sometimes, cause copper to turn weird colors. And xylene doesn't, but it will take off most things that acetone will.
    Last edited: Jan 18, 2022
  13. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Ok perfect, I did check out that link and noted that Xylene will often take of things acetone won't but I didn't really extrapolate further from that. I think I'll grab some at my convenience, I dunno why my local stores don't carry it when some of the surrounding ones do. Next time I'm adventurous enough to leave my quiet little town I'll have to look. lol

  14. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Just for completeness sake I figured I'd update everyone on what this coin looks like tonight. I didn't bother editing and uploading pictures because it looks exactly the same as it did after the 30 minute acetone soak. It certainly seems like what I have here is some Verdigris. I don't plan to take this coin any further at this point as Verdi-Care is not currently available. If and when it is, I may use this coin as my test subject once more.
  15. GDJMSP

    GDJMSP Numismatist Moderator

    Just be aware that when you get some that Verdi-Care, when used properly, will usually remove light verdigris, (your coin qualifies in that regard). But when the verdigris is heavy, not so much. I guess the point here is that one needs to be selective when deciding what coins to use it on, and what coins not to bother using it on. And even then expectations need to be kept realistic.

    The stuff works, but it's not some "magic elixir".
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  16. Jeepfreak81

    Jeepfreak81 Well-Known Member

    Ya, I don't really believe in miracles myself so none expected. HAHA, but I would like to try it out and have it on hand for anything of value that I'd like to save from further damage or feel would look more appealing without the green goo, so I'll keep a watch out for it's availability to open up.
  17. Kentucky

    Kentucky Supporter! Supporter

    guess what this is made of...
  18. CoinCorgi

    CoinCorgi Derp, derp, derp!

    What color was she when first erected?
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  19. Kentucky

    Kentucky Supporter! Supporter


    Of course VerdiCare wasn't around then
  20. Jeepfreak81

    Jeepfreak81 Well-Known Member

    THAT'S where it all went to, no wonder I can't get any. LOL
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  21. Jeepfreak81

    Jeepfreak81 Well-Known Member

    But what's the flame made out of? I actually don't know, I knew she was copper though.
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