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 Replies: 13 / Views: 2,210 |
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Valued Member
United States
136 Posts |
I have a question. Does coppy adversely react with mylar?
I ask this because I bought one of those (actually three since it came as a set) copper rounds just because I thought they look neat and were interesting to me.
Well when I got them I just wrapped them up in a paper towel and put them in a paper bag until I could get to putting them in a flip (I didnt have any large 2.5 x 2.5 flips). Well I got the flips so I dug out the rounds and one of them had some tarnishing on it which I guess I'm not all that surprised by one of them had none and the other had just a very small spot of tarnish.
I took the one with no tarnish on it, put it in a flip and stapled it. That was this morning. Before I left for work I was at my desk where the flip was sitting and I noticed that the copper round had developed some tarnishing on the high areas that were making contact with the mylar.
It was absolutely not there before putting it in the flip. So the only conclusion I am left with is that the mylar somehow reacted with copper or being in the flip and not completely air tight (which its no big deal with these things since I got them as a novelty thing anyway) has reacted in some way with the air. But if that is the case, why only the high spots?
Im not sure how copper pennies differ from this piece of copper but if there is a difference can someone tell me what it is?
Also, not that its a valuable thing or anything like that, but is there a way to clean off the tarnish and/or protect it from further tarnishing?
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Bedrock of the Community
United States
12437 Posts |
What kind of paper towel did you use?
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Valued Member
 United States
136 Posts |
Just a regular, typical household paper towel. I dont recall the brand at the moment but I can find out.
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Bedrock of the Community
United States
12437 Posts |
Mainly I wanted to know if it was a fluffy white paper towel from a roll or a tan/brown folded paper towel like those typically found in commercial restrooms. The latter kind can sometimes have a relatively high sulfur content from the treatment of the wood pulp to make the paper stock. If you want to experiment a little with the concept, get yourself a stack of Taco Bell napkins and wrap a few silver and copper coins  |
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Valued Member
United States
136 Posts |
Quote:
If you want to experiment a little with the concept, get yourself a stack of Taco Bell napkins and wrap a few silver and copper coins
I think I'll just take your word for it and pass, LOL. BUT, I will keep that definately in mind the next time I consider wrapping something up in a paper towel. |
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Pillar of the Community
Canada
1733 Posts |
some paper towels contain high concentrations of residual bleaching agents. They will turn silver/copper alloys blue with only minimal contact and shiny copper will start reacting within hours of touching it since it has no patina to protect it. Keep in mind, that any air borne contaminants rapidly affect raw shiny copper too. This can be anything from candle smoke to acids lifted from your cola by the CO2.
I use copper rounds to experiment with for other reasons but I too have kept a few and they look great even after years in mylar flips that I store with desiccant packs.
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Valued Member
United States
136 Posts |
When I put the round in the mylar flip, it was perfect. No toning or anything. And it turn a brownish color, not the blue you mentioned, but of course I have not looked at it under magnification either.
I guess my main concern is
1. Do I have something akin to contaminated or defective flips (I bought my latest stockpile from the same vendor)
2. What is it going to do to any pennies I actually store in them? I have not yet put any pennies in the latest flips I have bought, but now I'm kinda hesitant to do so.
Im even kinda more concerned about the quarters I have put in the recent flips I bought. Quarters are where I got started in collecting and are by far my biggest collection of coins and I just put a bunch of extras I had in these flips.
I will try and get a pic of the copper round when I get home and post it up.
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Pillar of the Community
United States
860 Posts |
I would tend to suspect that the contamination was from the copper round and its reaction to air ( since a stapled flip is open to air. 999 copper is very reactive relative to pre 1982 95% copper, and since the manufacturer of the round might not be as fastidious as the US Mint, lubricants and cleaning agents might be on them.
Jim
P.S. I didn't answer your question, sorry. No mylar will not react with copper.
Edited by desertgem
06/02/2011 01:38 am
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Bedrock of the Community
United States
20753 Posts |
One of the problems is exactly what type of so called Mylar are you referring to? By that I mean try to remember that MYLAR is a trade name and may well be different by different manufacturers. Quote:
A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the most well-known trade names are Mylar, Basically speaking, no MYLAR product should not react with Copper. However, note I said SHOULD. Since the patent is long passed, many manufacturers today make what might be called MYLAR but could well be similar or not close at all. In reality, usually what you discribe is due to what the Copper was exposed to prior to being encapulated. |
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Valued Member
United States
284 Posts |
I would guess that keeping the coin in the paper towel did something. Some reaction began and continued while it was in the mylar. I try to carry a few Ziploc bags with me that I use for finds in spare change. One coin per bag. Even then, just in case, I rinse/soak the coin in acetone to get rid of anything that might have made its way from the bag to the coin.
-- Boris
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Valued Member
United States
136 Posts |
What everyone is saying makes perfect sense, but I keep coming back to the fact that there was absolutely no tarnishing on the piece when I put it in the flip. It went straight from the paper towel to the flip. I suspected something with the flip, but they also are not sealed off either so it could have been a reaction to something in the air, but that leaves me with the question as to why it did not happen before hand, why was it so pristine when I pulled it out of the paper towel.
I guess we may never truly know though I would like to for the sake of the pennies I need to put into an album. I think what I will do is take a few from my change jar and throw them into a flip and see if anything happens.
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Pillar of the Community
United States
860 Posts |
"I think what I will do is take a few from my change jar and throw them into a flip and see if anything happens."
experiments are always fun.
Take before /after photos under as near of conditions as possible.
Rinsing with pure acetone and allowing to air dry before inserting will help remove contaminants on pocket change.
After putting into the flip, put some of the flips in a zip lock bag , squeeze the air out and zip it.
Toning/corrosion is not a nuclear reaction, it is a chemical reaction and depends on supply of reactants. With no water, gases, or very energetic light, there should be no reaction. Without these, previous toning/ corrosion will stop and not continue to increase
Jim
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Valued Member
United States
136 Posts |
I do think I am going to experiment with them a little. They are just copper rounds that have no value other than the copper which I obviously paid more than the value of the copper to have them, but I'm okay with that also just because I think they are kind of neat.
I am trying to get set up to conduct a few experiments but I have to get my copy stand in first so I can take some decent pictures with my digital SLR. I am super curious about the effect of acetone on the coins and then being in flips. And since copper seems to be the most volatile of the metals with relation to coins I plan on using the copper rounds to test with. I may even buy a few more just to play with.
If silver were not so flippin high right now, Id buy me a few bouillon bars of that to play around with.
Since joining this forum I've seen a few posts about cleaning coins and read some other information and its an interesting discussion. While I'm personally on the fence about it as I can see both sides of it, it seems to be a 'taboo' type subject. But since it is available as a service from some graders I believe and I've personally seen books on the subject that leads me to believe that it happens way way more than probably admitted to. Which is fine, but with the incident with my copper round, I want to know the not only the effects of cleaning but to be able to spot it as well when I'm out buying coins. I also would like to see if I can discover what happened with this particular round and see if its something thats a fluke or something that can be addressed in any manner. If it happened to this copper round, then it can happen to my coins and I certainly want to avoid that.
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Bedrock of the Community
United States
19930 Posts |
Copper will not react with Mylar. I agree with Jim. More than likely there's something on the coin. Rinse your coins with acetone before storage and keep the 2x2's in a ziplock bag. Quote:
I am super curious about the effect of acetone on the coins and then being in flips. Acetone is extremely volatile and will instantly evaporate from the surface. By time you put it into a holder it will have completely evaporated. |
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Replies: 13 / Views: 2,210 |
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Posted 06/01/2011 6:46 pm
