PVC use in coin supplies???

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Not really. It starts with temperature, light and humidity control.

Not by my standards.

Air is a necessity for metal objects to be conserved. It is high humidity that kills the coins, and swords, and musical instruments, and medieval armors. Humidify should be maintained as much as possibly at about 24% - 27%. Above thirty percent, it increases and catalyzes volumetric reactions. This is especially true for silver, but also true for gold, brass, copper and steel.

That is a common misunderstanding. Oxygen is certainly not required for oxidation.

If you restrict the flow of air completely you will have unintended consequences, such as oxidation with wood, plastic, other metal, etc.

For a common collector, they are better off protecting the coins in a wood box with Mylar, 100% proven and rated plastic flips and covered by the archival film that I pointed out before, in a controlled environment as much as reasonably possible.

Ok

http://www.conservartassoc.com/faqs.html

http://www.nyu.edu/gsas/dept/fineart/
http://www.columbia.edu/cu/arthistory/graduate/

 

I went to Columbia a long time ago, but today, this might be the best program...

http://www.nyu.edu/gsas/dept/fineart/conservation/index.htm

 

sigh..

 

Amanda, conservation of any material does have the same philosophical intent, but often the details have to be derived for different types of materials. In many cases crossing over of conservation techniques from one area to another can have horrible consequences. The general conservationists of many 1800 to mid 1900 museums, including the nationally known ones in NY and Washington, often polished and damaged early coins as they didn't really understand the metals. Likewise a coin conservationist could think complete lack or air or moisture ( as for coins) should work for paper and cloth items, or even naturalist preparations of bones and skins. Of course we should know better now. However many store their paper money/stock certificates , etc the same as their coins, which have different consequences, but all bad.

The vapor pressure of silver , gold, nickel, coin metals is basically 0 at normal temperatures ( they don't outgas), where as paper and natural organic based substance do. So for the first (coins) air tightness, near vacuum, zero humidity would be best. For natural or outgassing substances such as paper, clothing, a raccoon specimen requires varying ranges of temperature, and humidity. Paintings and even a few ceramic objects out gas and must be given consideration.

Wood does out gas rather strongly. If you can smell a piece of unvarnished wood, it is out gassing. Tannic acid can affect coins and thus the wood and varnish/wax should be chosen for low reaction around coins that are not is an airtight container. As Doug said Mahogany is generally thought as the lowest emitter so that is what was used, but even it is much higher than most plastics. I know it is weird that so many sets are issued in wood containers, but ~ oh well.

I do find a little humor in that I purchased a modern rendition of a coin cabinet at a club auction ( made by the Franklin mint for a long ago promotion) and no one else bid as they knew about wood/felt/ and coins. I am using it to store my crystal and gemstone collection IMO.

Jim

 

in the real world, unless a metal is allowed to tone healthily, it will corrode and oxidize with whatever is available, including plastic.

 

I don't know much about coin conservation but I know oxygenation does not require oxygen. If I'm understanding this correctly, though, you guys think that my wooden slab cases are deadly to my slabbed coins.

Ruben

 

Not deadly but they are a risk to the coin. Different woods outgas different stuff. Some gases go thru slabs, airtight or not. Same thing goes for storing guns with coins. It's a risk.

 

Is it cool and have low humility in that storage? Then they might be fine but the plastic risk.

Amanda

 

This is not 1800. I know this first hand because i have to constantly try to fix mistakes made in the 1800's and the 20th century. One result of this experience is that in restoration, and even in conversation (two very different things), whatever is done, we make an effort to ensure it is easy to identify and maximally reversible. This has not much to do with the current topic, but i enjoy talking about it 28 hours a day.

The chemistry of conservation, something I do not have a degree in but only some background, has nothing to do with vapor pressure, but reactivity, of which there are mostly 3 kinds that have to be most accounted for: redox, acid-base, and biological induced.

Metals will react in any situation where there is chemical potential. Metals with a a normal chemical potention in the -.500mv range, are aggressive chemical reactants and catalysts. Metal alloys, a bit less. Humidity is the true enemy of metals, that and a lack of an even, healthy metal tone. Keep in mind that conversation of items like coins, for example, is far different than what we would do for musical instruments and silver ornamental dining utilities (see the Fricks wonderful collection). Also, what museums consider conservation and what coin collectors consider conservation are two different things.

In the case of coins, with the emphasis of original surface and delicate design, primary toning is vital for long term conversation and therefor coins should never be in a vacuum or an airtight condition. An item can NOT be conserved if it is existing in an environment that is not natural or reasonably maintainable for the objects usage.

 

I couldn't disagree with any part of that statement more. The primary damage causing factors to ANY metallic surfaces are water and atmospheric gasses. The lower the exposure to such factors, the better off a coin will be for long-term storage.

 

Lucky for me then that I have seniority ...

 

Allow me to give you one example. H2S is typically in air between 0.11 and 0.33 ppb, and can be much higher depending on several factors. H2S is extremely corrosive to metal and, over time, can completely cover the surface of a silver coin with sulfides which will eventually cause it to turn black. Using your logic of allowing air to get to the coin surface, eventually a coin would be completely ruined.

Reference: http://www.atsdr.cdc.gov/toxguides/toxguide-114.pdf

 

I don't think that by repeating what I wrote can help you understand better what I mean. I'm sorry I am not a better teacher.

Amanda

 

Hi BadThad. You probably know the answer to this question. I have always understood that some gasses can go thru slabs even if the edges are sealed. How fast can this happen? Is it even a worry?

 

I know my wood cases are much cooler than my steal box.

 

BTW - I HATE your icon I just thought after all this time, you should have the benifit of that knowledge ..

 

Oh. That bird you are flying is lost. He is just flying around in circles. My bird is on a mission to get somewhere.