How long does it take a coin to develop PVC damage?

ajaan

Let's say you put a coin in a PVC flip. How long before signs of PVC contamination?

coinkat

I think it depends on the environment... heat and humidity, and other possible issues such as storage

ecos

coinkat is very correct. It really depends on the environment.

I made a huge mistake of putting a portion of my collection in my parents attic while I went off to grad school. When I came home and checked (while sweating to death in the 120 degree heat of the attic) all of my coins turned into PVC farms. There was green growing from all over. It was horrible. Luckily it was alot of junkier stuff and the good stuff was saved with acetone.

So it can happen over the course of months to a year, but I have seen coins in PVC flips for a number of years that were still okay. I will never take the chance of using them again.

AuldFartte

I pulled some old coins out of PVC flips that had been there for at least 18 to 20 years. Most of the coppers were looking green ranging from mild to "neon"

The silver, however, was only slightly "sticky" with no evidence of surface damage after a bath in xylene. A few silver pieces weren't sticky but just smelled funny, so I bathed them, too.

These coins were all stored in a garage in the high desert area of New Mexico ... very little humidity, but loads of summer heat. Oddly, the more recent copper coins (20th century stuff mostly) suffered the most damage, while the 17th thru 19th century coppers were in much better shape.

ajaan

<< <i>Oddly, the more recent copper coins (20th century stuff mostly) suffered the most damage, while the 17th thru 19th century coppers were in much better shape >>


The later suff is made from bronze, the earlier is copper. Maybe bronze is affected by PVC more than copper?

Aethelred

<< <i>

<< <i>Oddly, the more recent copper coins (20th century stuff mostly) suffered the most damage, while the 17th thru 19th century coppers were in much better shape >>


The later suff is made from bronze, the earlier is copper. Maybe bronze is affected by PVC more than copper? >>



Or perhaps the natural toning/patina helped save them.

AuldFartte

<< <i>

<< <i>Oddly, the more recent copper coins (20th century stuff mostly) suffered the most damage, while the 17th thru 19th century coppers were in much better shape >>


The later suff is made from bronze, the earlier is copper. Maybe bronze is affected by PVC more than copper? >>



That just might explain it

wybrit

The chloride in the PVC outgasses and leads to HCl. As coinkat stated, environment is the key factor. More heat ==> more outgassing plus faster reaction rate. More humidity ==> more dissociation of HCl gas into corrosive acid. I must explode one myth - both copper and bronze are easily attacked by HCl.

Although I do not recommend it, storing coins in PVC flips in a very cold, dry place would likely not harm them for some time. I should try running an experiment with some 1967 Brit pennies and PVC in my "spare time."

Or perhaps the natural toning/patina helped save them.

Excellent possibility. Many metal oxides and nitrides afford protection to the underlying metal. One example is aluminium (sylvestius would pronounce this "al-yoo-min-yum"), which in its pure form reacts quickly, is protected from attack by its oxide.

Similar concerns with PVC exist in industry where thin metal layers are deposited. PVC is used to reduce static electricity discharges, but its outgassing in humid environments can corrode these same films very quickly.

Aethelred

Wow Wybrit, that was deep!

wybrit

Just playing the forum nerd for a day.

Aethelred

And doing a darn fine job of it!

SYRACUSIAN

The silver, however, was only slightly "sticky" with no evidence of surface damage after a bath in xylene. A few silver pieces weren't sticky but just smelled funny, so I bathed them, too.




I received 5 silver coins today,from a Swiss seller that have obviously PVC on them.No evidence of damage after close inspection, just that green colour. I'm not at all experienced with this subject, other than reading the informative posts here. From what I understand, I need to give them an acetone bath, right? For how long? And do I just leave them to dry afterwards?

Please note that the coins are choice to gem unc, nothing expensive, but nice shiny coins and I wouldn't want the luster to go away. One of them just smells, not bad, but this soft plastic flip smell, so I think it needs the same treatment.

Also, I don't think I have any access to any sophisticated solutions, other than acetone. Any help will be greatly appreciated.

trolling

Syracusian, what I do is use several glass jars filled with a small amount of pure acetone, enough to cover each coin. Swish the coin around in the first jar to remove most of the contaminants, then transfer the coin to the next jar and do the same, then do it in the third jar. This should be plenty enough to remove all the residue and leave you with a clean, PVC-free coin. You can hold the coin with your fingers by the edges; a bit of acetone won't hurt you. Be sure to do this in a well-ventilated environment, and do not smoke or have any flames nearby. Good luck.

MacCrimmon

Syracusian, if you can get xylene (xylol) it seems to be more aggressive as a solvent than acetone. Also, it's best to let real problem coins soak for several hours at a time. Those little baby food jars are ideal since the screw tops prevent the fumes from building up and the solvent from evaporating.....and, do this outside if possible......your liver will thank you.

Steve27

I received a coin in an old PVC flip recently. It was pretty obvious that the coin had been in there for quite some time, but the coin wasn't damged (a little acetone and everything was fine). Thus, I agree with those who indicated that environment plays a big roll.

Conder101

<< <i>Let's say you put a coin in a PVC flip. How long before signs of PVC contamination? >>


The topic question asked about PVC DAMAGE, the first post asked about PVC CONTAMINATION. They are not the same thing. You put a coin into a flip that has stated to have its plasticizer leach out and you have PVC contamination bang right now. But depending on how the coin is stored, even in that flip, damage may occur in just a few weeks, months, years, or even never.

rhound1977

I think PVC damage can also cause 'green toes'.........