PVC use in coin supplies???

And probably less humid, both of which are major pluses. There is a curing affect to wood, however. You should expect some reasonable toning. toning can not be avoided though.

 

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They are mostly Bust Halfs and Half Dimes.

 

Besides the gaps mentioned by Doug, ALL plastic is permeable by gasses and water. If you do a google search, you can probably find engineering tables that list permeability of different plastics.

 

Maybe I didn't fully answer your question. It has to do with the interstitial space between the plastic molecules. Believe it or not, a layer of plastic is kind of like a tightly woven cheese cloth....that's the best analogy I can think of.

 

Not only are plastics permeable to molecules such as H2O, they are permeable to other molecules. Generally molecular wt is a fair consideration of permeability. Water is 18, air mixture is considered to be 29, Hydrogen sulfide is 34, and at first glance it would seem that Hydrogen sulfide would be the less worrisome, except, that the diffusion mentioned by Doug, where the movement of air and water molecules go in or out determined by partial pressures, once H2S diffuses in and reacts with the metal surface, it can not leave, and partial pressure inside becomes less and enhances the migration of replacement H2S from the outside through the barrier. If water vapor becomes part of the reaction , it also can react similarly. However, the thicker any of the plastic barriers, the slower will be the process ( more molecules to run into). A coin sealed in a inch thick piece of acrylic plastic will probably never tone/corrode visibly in a person's life span.

Practicality is needed as even glass or any molecular substance has permeability to some level. That is why dessication and sulfur entrapment such as use of Intercept foil or use of scrubbed sacrificial copper or silver coins, will intensify protection for coins inside of plastic ( mylar or hard) holders

In gemstones, ugly colored sapphires and other stones are diffused with beryllium or other molecules to produce an intense coloration ( Gemology's AT problem, but it can be detected by testing). Heat loosen the gemstone's lattice ( Thad's cheesecloth illustration) so molecules which are also moving faster can infuse.

Jim

 

As I tell noobs: mo layers = mo betta

For my Lincolns, many layers are involved. For the HQ stuff:

1) airtite
2) airtite into a 2x2
3) 2x2 into plastic binder page
4) binder page into a ziplock with a red sacrificial cent and desiccant
5) binder page into tupperware
6) climate controlled environment

 

??

Rofl

 

I'm glad that all the arm chair preservationists are on the same page. It makes one wonder how any coins actually survived several thousand years without tupperware. This is inconsistent with rational approach to conservation. The Mona Lisa doesn't get this kind of conservation...

Really? This is so over the top as to be laughed at by my colleagues when we read this. I don't mean to mean spirited here, but come on. We have found 2500 year old coins with their luster intact in jars stuck in the mud.

 

Sorry but you don't know what you are talking about.

 

Laugh all you want. If you want to be assured your copper doesn't change, this is what is necessary. How many mint, red copper coins have you pulled from "jars stuck in the mud" for 2500 years?

 

Interesting thread. I would change that question and ask how many Lincoln cents were pulled from jars 2,500 years ago? Seriously, let me ask a question. How did red 1909 Lincolns come to exist. What is the chance regardless what you do that in 400 years they will remain red?

Ruben

 

Factually wrong

 

Well, don't tell my boss.

 

A) - This isn't a debate. You can learn something from me, you can not. But I'm not debating and I have nothing at stake here.

B) No, it is far more delicate than a coin and more sensitive to air, humidity, light and oxidating gases like Sulfur Dioxide. It is also far more rare and expensive, if you can put any price on it.

C) That is a stunningly incorrect assumption. Generally they are in a cool environment, although many of the recent finds are in anaerobic and wet conditions, and even more found in caves or other archaeological sites. And please, don't suggest that ancient pottery is air tight.

D) Low humidity and cool air is the first consideration.

 

Except that other than the gold, neither of the other two have ther original mint color, which was their point. Sure they still have their detail and luster, but not their original color.

 

I agree, but it has a nice brown tone which protects the coin, as i said before. I believe, and I don't collect cents, that it would receive a BN notation.

The real mistake I made was, I'm not sure if those coins have been previously polished
I should ask to look up its curator record.

Oh well..

 

Well, you just proved my "factually wrong" point.

Most of us copper collectors like our mint, red and toned coins to stay how they are. The copper coins you posted have heavily browned. If we followed your advice, our nice, red, mint state coins would look just like that eventually....and the gold coin doesn't count since gold is pretty non-reactive.

 

gold tones