Do Cardboard 2x2's still have PVC? I think so

I like rusty staples. They can be a sign that the coin has been protected for a long time. I have a Morgan in a rusty staple 2x2 with a price of $3.25 on it. It will never be "cracked" out

 

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But why does it react with plastic?

 

I have to differ with you on this. Plasticizers for PVC are fairly high molecular weight compounds that tend to be oily (dioctyl phthalate or DOP is one of the most common) and migrate between the polymer strands to loosen them up and make the plastic softer. With age, the plasticizer can leach out onto the coins creating a gooey mess and providing a convenient medium for other chemicals to get trapped in and damage the coins. Old PVC can decompose and release hydrochloric acid (or hydrogen chloride gas...kid of the same stuff) and the plasticizer can make a toxic salve with it to start verdigris on the coin.

 

Yeah, I think I have. Have you? In a response in the post "Is this Verdigris or PVC damage on my cupro-nickel coin," badthad says:

"PVC is a catylist for verdigris formation created by hydrochloric acid forming cupric chloride. PVC damage and verdigris are essentially one in the same."

I understand the difference as well, but as he said, they are linked sometimes

 

No, I didn't read that thread. I was basing my comment on his post in this thread. Then again, I think I read another.......no wait.......it was......but now it's not.........I give up!

Chris

 

Okay, so it's not just me. Would you like to expound on this? What do you put them in now? Have you noticed this with other types of coins, like Jefferson nickels etc?

And I don't think Insider's comment is the whole story, ie that it's simply the environment. My other coins are fine, aluminum probably faring the best. So perhaps it's also the fact, as condor or someone mentioned, that copper is the most reactive etc.

 

So, in sum, I guess I should not use these holders with cents? I guess I'm not going to hoard low value wheats any more, or IHCs. I'll put the better ones in the hard snap together 2x2s. I'm not so sure it's the environment since I live in an area not known to be humid.

 

Right on brother, we're not differing. You just said it better, I agree 100%.

 

I would say that's at least partially a result of environment, rather than just attributing it to "air".

The leather undergoes multiple treatments in the process of becoming a bag, including tanning, dying, and sealing. There might also be adhesives present in some cases. Also... we're talking about brass. Isn't Zinc the most reactive of the transitional metals?

 

It's not reacting with plastic, per se. It's reacting with the gases released by chemicals associated with the plastic. Kentucky's explanation is likely the most thorough, but, simply put, the softening element of PVC is an additive coming from a group of molecular material classified as "plasticizers."

PVC is rigid and brittle at room temperature, but when it's heated up, it becomes more malleable. Think of how a plastic container is a tad bit softer when you leave it in the microwave too long. Now, while the PVC is hot (and therefore malleable), plasticizers are added to the mix. They wiggle their way between the PVC molecules preventing those molecules from rebonding into the rigid matrix.

Over time (and whenever it heats up), the treated PVC gases out some of the plasticizer which reacts with some of the air, creating hydrochloric (HCl) acid. What makes matters worse is that PVC is actually pretty resilient against our acidic friend, which means the gas may be forced to stay in place longer, which means your coins are forced into a high reactivity environment.

Now, while true that the metals will normally oxidize over time, the presence of HCl changes things. The HCl means that acid is around destroy the bonds of the metal. This is the reason why the PVC "gunk" is bad, which leads to the use of acetone to break up the PVC and plasticizers. The gunk is an acidic environment. If it's left to interact with your coin, you may find a pitted surface under the blue/green slime.

 

Thank you, you know I have enormous respect for you....Yuge, I tell you, Yuge