Like a lot of people, I accumulate Lincoln cents. It's unintentional, but they pile up. Some are shiny and new, others are road kill. I know verdigris can be contagious and it made me wonder if the 21st century disease of zinc rot can be, too?
I have been told both ways about Verdigris. Some say that it can't transfer, and others say that it can. I think that the only thing that can transfer is bronze disease.
Looks like it's a little more complex than moisture in the air creating zinc dust. But I don't think it's contagious. https://onlinelibrary.wiley.com/doi/pdf/10.1002/9781118762134.app10
The one bad apple rule...... I been told that zinc rot is a reaction that occurs when the zinc is exposed through damage or whatnot. Once the core is exposed one metal becomes an anode and the other a cathode.... It is why I have an odd block of metal on the side of my boat motor. Any corrosion is supposed to be directed at that block of sacrificial metal on the side of the motor..... Now I am only repeating what I been told and if that is the case I would think zinc rot could certainly be contagious. I think the right guy to answer would be @-jeffB
I'm thinking that it can be effectively contagious (salts from one rotting coin draw moisture that can then accelerate the process on others), but I'm not going to weigh in further until I've read the paper @Burton Strauss III posted.
Reactions in salt water are a different animal. That's why I found the article interesting, it focuses on atmospheric reactions.
I believe that it can be but only if the coin affected comes in contact with one that has freshly exposed zinc. I’d keep them apart just because I don’t want them looking like this. I forget which is the obverse and reverse but it’s the same coin, a zinc one cent. If you blow up the picture you can make out a few of the letters near the rim.
It transfers. So does zinc rot. I believe zinc rot transfers by holding moisture. Verdigris may be the same thing.
Just a non-scientific anecdote - I had cents saved in a metal bank from when I was a kid, mid 70s is probably when I put the last cent in there, and left it alone for decades. I finally emptied it out and went through them in 2016. So they had been in there for 40-45 years. Some had really bad verdigris, majority had none at all. Many were still red. If it is in fact contagious, it must be a very slow process.
Some might find this interesting. In an original roll there used to be about a 55% chance that if a coin was oriented heads side up the next coin would be as well and vice versa. More to the point if you pull out a roll of BU zincolns and eight are rotted there is a very good chance they will be consecutive. I believe the first can be explained by a much lower coefficient of friction between a heads and a heads than a tails and a heads leading to orientations 'bunching up" and the second can only be explained by contagious rot. Verdigris is different and does tend to be very slow and far less common than zinc rot. But I do see it on adjacent coins quite often especially when oriented heads to heads. Of course it could be the contaminant causing the verdigris to affect both coins rather than "contagion".
