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 Replies: 12 / Views: 12,755 |
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Valued Member
United States
191 Posts |
I remember some of the older coin holders and storage boxes reacting negatively with coins but can someone give me an idea of what plastics are and are not safe to be used with coins? One reason I'm asking is I found some plastic storage containers that were intended to hold beads in the hobby section. These containers would be perfect for certain coins and supplies as they have many compartments. Any thoughts?
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Valued Member
United States
426 Posts |
As far as I know, anything with PVC is bad for your coins.
Check out this copy & paste.
PVC damage on coins is the result of improperly storing coins in soft plastic flips. The PVC chemical in the flips interacts with the metal of the coin, creating a slightly acidic reaction, which causes residual deposits to appear on the coin's surface. Copper coins are most vulnerable to PVC damage, followed by silver, and then gold and platinum.
PVC damage appears as greenish, milky, or grey streaks or haze. In severe cases, it looks like tiny green blobs on the surface of the coin. PVC stands for polyvinyl chloride; it is an additive used in plastics to make the material more pliable and less brittle. In coin collecting, PVC is most frequently encountered in the clear plastic flips in which coins are stored. As a general rule, the softer and more pliable the flip is, the more PVC it contains. The hard, stiff, brittle types of flips (made of Mylar) do not contain any PVC.
PVC residue has a distinctive smell, sort of like the smell you get when you open a cheap plastic toy. In mild cases of PVC contamination, you might not be able to detect the smell, but if you ever smell PVC after removing a coin from a soft plastic flip, even though you don't see contamination on the coin, you should treat the coin for PVC damage anyway as a precaution. Removing PVC residue is simple, but left untreated, it will eventually eat into the surface of the coin. Merely taking the coin out of the offending flip isn't enough; once the PVC cycle has begun, the acidic PVC cycle will continue to degrade the coin's surface until permanent PVC damage results. Reputable grading services will not encapsulate coins with PVC residue on them.
Ah, the power of google!
Edited by RealPeso
10/30/2010 01:32 am
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Bedrock of the Community
Australia
21788 Posts |
Some plastics are nevertheless suited to numismatics.
The two that spring to mind are acrylic capsules, which can be used for storing proof coins, and Mylar for storing stamps and banknotes.
I go to my friendly coin dealer and buy one or two acrylic capsules of very specific size for 50 cents each. Normally, these capsules have been recovered from broken proof sets, where the coins have been sold individually. I don't normally collect NCLT, but I bought a pair 1937 Great Britain gold proof 5 Sovereign and 2 Sovereign coins some years ago. I still have them, and they are both protected in screw tight acrylic capsules.
In this way, you can appreciate the weighty tactile feeling of these coins when examining them closely.
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Valued Member
United States
487 Posts |
I ask this question on CCF, and got such great information. I was storing my coins in a Rubbermaid container and didn't know if it was harming my collection till I looked up the recycling symbol on the bottom. You know the triangle with the #er in the middle. Well I Google it and found my Rubbermaid containers were just fine. Piece of mind. Hope this helps.
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Bedrock of the Community
United States
20753 Posts |
Unfortuately there are possibly a million variations in plastics today. Without knowing who made what you could not possibly know what the product is or does. PVC is just one of the many, many variations in plastic products and not all PVC is dangerous. For example if you look at any hardware store you would see massive amounts of PVC piping for household purposes. This is the hard version where nothing has been added to make it plyable yet soft PVC gives off gasses for a long time. Many plastic products today are made from recycled plastic products and the end results can vary extensively due to the massive different materisals used to produce them.
When it comes to using any product, plastic or orther wise, for coin sor any valuable storaging, always check with the manufacturer of that product for possible gassious emissions.
As an example I keep all my coin Albums in Zip Lock Plastic Bags but prior to that I contacted the manufacturer for possible damages from them to my coins. Found out since they are made for food storage, they can not have any possible damaging results for coins.
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Bedrock of the Community
Australia
21788 Posts |
just carl: As you have hinted, the types of plastics are many. Polyethylene is used in plastic bags. It is non injurious to coins, but not suited to the storage of numismatic items.
There are two main types of polyvinyl chloride PVC and uPVC-(unplasticised PVC), the difference is that uPVC has no plasticiser in it. This material is used for pipes. A plasticiser softens the plastic, but the plasticiser leaches out as a gas over a period of time and the PVC then slowly becomes brittle, but before that happens, it simply splits. The gassing is the aspect that adversely affects coins. I suspect that there are chloride compounds in the gas, which can turn bronze coins dark.
I do not know of any recycled plastics that are used for numismatic storage purposes.
Acrylic coin cases are often used by the mints for their proof products.
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Bedrock of the Community
United States
20753 Posts |
Quote:
just carl: As you have hinted, the types of plastics are many. Polyethylene is used in plastic bags. It is non injurious to coins, but not suited to the storage of numismatic items.
HUH? Am I awake yet? You do realize that Numismatics is the hobby of collecting coins, tokens, currency aren't you? What your saying is basically like saying I like cars but don't like automibiles. Or I like walking but don't like excersize. I like to wear sweaters but hate to wear clothing. As I mentioned I contacted the manufacturer of Zip Lock Plastic Bags about the material that those items are made from. They are safe for food, coins, clothing or even stuff found in your kids pockets.  |
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Pillar of the Community
Canada
3692 Posts |
Just so that I don't start another thread, I'm using Uni-Safe for my lower-grade coins. I'm wondering what type of plastic is being used, and what metals I should avoid putting in there (brass, CuNi, stainless steel, bronze, etc...)
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Pillar of the Community
United States
4989 Posts |
Given the huge premium that Rainbow coins seem to command, should we really be storing our coins in airtight plastic slabs or, rather, try to reproduce conditions that yield high quality natural toning?
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Bedrock of the Community
Australia
21788 Posts |
From a chemistry point of view, if a coin is in an oxidising environment, there is a possibility of degradation to the surface. Most chemical coin damage is of the oxide or chloride type (both oxidising agents). Oxygen can damage a coin, usually by being carried in the presence of water or water vapour. Chlorine is most commonly from chlorided plastics.
Polyethylene (C2H4) clip lock bags do not have chloride to leach out of the plastic, and should be OK for coins. Polyethylene is just a polymerised version of ethylene.
Edited by sel_69l
11/02/2010 08:33 am
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Pillar of the Community
United States
3283 Posts |
So are the big plastic bins, like at Walmart, OK for storing albums and folders with coins in them? |
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New Member
New Zealand
1 Posts |
this is the site I use for plastic products for my coins
bcwsupplies
Although this is an early post by Silver and we have rules about posting links for new members I have edited this post so you can see the name of the company he recommends but I have taken out their link.
As Silver lives half a world away from the supplier I believe he/she posted this information with the best of intentions.
If you are interested just look up the supplier or just add .com to their name
moderator
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Bedrock of the Community
United States
20753 Posts |
Quote:So are the big plastic bins, like at Walmart, OK for storing albums and folders with coins in them? Difficult to really know unless you can find out who made them, all the same material, when made and on and on and on with questions about those things. If you can not contact a manufacturer of a product due to not knowing who they are, might not be something you want to try. As I mentioned so many plastics today are recycled products so could be almost anything. If a product is not made for the preservation or storage of food, may well not be suitable for coins. However, you don't normally eat coins but you do eat food so there could be some problems with some plastics for coins but not for food. Or could be dangerous for food but OK for coins. |
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Replies: 12 / Views: 12,755 |
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Posted 10/31/2010 01:53 am
