Green Cover On Coins

Nah, I'm smiling while I'm typing! I guess I come across as the mean scientist, but I'm not really.

Bad Thad: Someone once told me that one of the main components of verdigris was copper hydroxycarbonate. I have only schoolboy chemistry ability, but is that a double salt?

Quote: People read something on the internet and think that is the absolute truth since it is on the internet.


Yes, JustCarl, I agree with your assertions about the problems of Wikipedia and the Internet at large, however, those capable of critical thinking while not necessarily expert in Chemistry and Engineering, are able to navigate the information available. Besides those credentials don't necessarily lead to an applied and informed opinion about any sub-specialty either unless the person possessing that C & E background also has some capacity for critical thought. I will assume you understand this point but if I am not being clear, consider the problem with the western practice of medicine. Doctors have "the expert" designation for their study of the facts and systems involved in human health but that in itself does not make them good practitioners of medicine.

I would rather that you would have responded to my last post to point out where my statement of the processes and source of tarnish/patina versus verdigris are incorrect, rather than pointing out the limitations of information available on the web as if I am unable to discern for myself what constitutes a reliable source of information.

While the Internet may be a lesser source for information about the physical sciences than for, say, history, disparaging the Internet because it doesn't consistently meet your intellectual standards about a particular topic and then pointing that out in the forum as if I wouldn't know the difference is both pedantic and a bit patronizing on your part.

I don't know that you meant it that way, but since I replied to BadThad's dismissive reply as the verdigris expert.I'm now deflecting additional replies from people who aren't contributing to the scientific basis for the verdigris versus patina discussion but rather are trying to reinforce BadThad's expertise and seemingly reinforce my point of view on the topic as limited at best.

Please contribute to the facts of the discussion rather than engaging methodological concerns in epistemology.

As it stands, no one from the "everything is verdigris" camp has addressed the assertion by equally qualified sources that bronze patinas protect bronze from deterioration. Please explain the difference in passivation between a patina and bronze disease both of which are being called verdigris. Why does verdigris protect bronze under certain conditions and destroy it under others?

Nothing stays exactly on-topic.. there will be other comments and asides along the way. From what it sounded like, just carl was making a general observation, not pointing fingers at anyone in particular. I understand comments of this nature may be frustrating while you are waiting for a definitive answer, however, he did make a valid point. Comments that do not directly answer a question should also give you some means to get to know the people here while you're waiting.

Everyone contributes in their own way - you are, of course, free to ignore those points of discussion you feel do not add any value to your main objective, but please do not disparage anyone while doing so.

Thad explained verdigris in detail in a couple of posts but here is the only one I can find: https://goccf.com/t/61519#482624 - the entire thread might be worthwhile reading, but that one post outlines the elements involved for verdigris. I'm sure he'll also respond to the question.

That's cool, I'm just explaining the science. I will add that it's true about a "protective" coating. A light covering of verdigris WILL provide "protection" to the surface in that those metallic sites are occupied and only able to react if a stronger anion comes along. Nonetheless, the verdigris is not static, it is in a constant equilibrium state and the corrosive process will continue on a micro-scale. If the coin is well protected from air, water and temperature swings, the rate will be so low that you won't see the corrosion process progress in your lifetime.

Just to add one last, hopefully, notation. If you'll read back a few posts, you'll see where I explained what happens to Copper or Copper mistured wires and cables used for Grounding systems. If not properly covered with lesser or non corrosive coverings, they completely dissentigrate. Salts and acids of all kinds in and on the ground attack those grounding systems and distroy them. Copper and Copper mistures are always used due to their great conductivity but unfortunately they react with so many other elements, their effectiveness is short lived unless properly protected.
Naturally coins are not normally kept in or on the ground but the end results are similar. Your breath, nasal drippings, your finger oils and acids, coin carrying pouches and on and on with everything possible to ruin a coin.
Which is why the Mint workers everywhere have a life time job.

You're right JustCarl...I did miss that piece of your commentary and personalized it instead...and regarding your "green" problem...may I recommend www.verdigone.com?...thanks to you also JC for your patience and I get what you're saying about the better part of our population...though we went through this in derivative fashion first with radio and then with television; now with the internet...