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 Replies: 26 / Views: 5,309 |
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Valued Member
Spain
134 Posts |
I suppose many people have asked this many times before, but I've been looking over the net and can't find the answer I'm looking for.
I bought fairly recent bronze and copper coins that had absolutely no toning -even when they were up to 25 years old- in just a year with me they began getting darker at an alarming rate.
These coins are too numerous and not that valuable, so I can't afford to buy airtight capsules or self-adhesive coin holders for each of them; I just put them all in coin folders (you know, these plastic pages with 20 pockets, or whatever number). I'm not sure if it's the plastic on the coin folders, of if it's the fact that they are not airtight; I'm not even sure if the plastic contains PVC.
So, I urgently need help with 2 questions:
-What's the best option (the cheapest and easiest one) to keep many bronze and copper coins from toning?
-And, how do I know if my plastic holders / folder pages contain PVC?
Thanks Edited by silvermaniac
06/24/2013 11:59 am
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Bedrock of the Community
Australia
21788 Posts |
Strangely, some red unc copper coins retain their full red for more than 100 years. It would depend on the storage conditions.
I have a couple of Victorian 1/4 Anna coins of India, like this.
Probably the best way of preserving the full red richness of an uncirculated bronze coin is to give it a spray of clear acrylic laquer, let that dry, and put it in a screw capsule, or in a Mylar 2x2. I have done both.
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Bedrock of the Community
United States
19949 Posts |
More protection from air will help. Also, I don't like albums and folders, they will tone coins. Use coin tubes instead, then store the tubes in ziplocks with a sacrificial red cent in the bag and a desiccant pack. Then keep the bags in something like Tupperware in a controlled climate.
You can never completely stop the toning process, you can only slow it down.
Lincoln Cent Lover!VERDI-CARE™ INVENTOR https://verdi.care/
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Bedrock of the Community
Australia
21788 Posts |
Depends what category of coins you happen to be interested in.
If it was noodling finds, I would certainly agree with BadThad.
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Pillar of the Community
United States
836 Posts |
An idea I would suggest would be acetone dip and then handle only with cotton gloves afterwards. This will remove any finger oils and dehydrate the surface, so it should keep them red longer.
BadThad I know folders and albums tone coins, but how hard is an album such as Dansco 8100 on red cents?
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Pillar of the Community
Australia
1006 Posts |
Sel and Badthad they are great ideas although to continue on from Badthads sacrificial red cent wont really do anything although if you put something like a zinc coin with the red cent that should prevent the atmosphere reacting with the other coins in 2x2s. Learnt this from year 12 chemistry basically if you put a more reactive metal with less reactive metal the more reactive metal will have to decompose fully until the atmosphere begins on the less reactive metal.  Hope I helped p.s curious people can read about this on google as sacrificial anodes or cathodic protection |
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Bedrock of the Community
Australia
21788 Posts |
Using zinc as a sacrificial metal won't work unless the coins are in unprotected close contact with each other.
That introduces the problem of mechanical abrasion.
Sacrificial zinc anodes work quite well when attached as blisters either side of bronze prop shaft glands in large boats.
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Pillar of the Community
United States
1391 Posts |
Can you protect zinc coins by using clear acrylic laquer?
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Valued Member
 Spain
134 Posts |
Thank you for all your suggestions; from which I gathered (correct me if I'm wrong) that the main problem is not the contact with the plastic but oxidation due to moisture and air. For which some suggested:
-Chemical products: I wouldn't like to do that, I would prefer the coins to remain as close as possible to the original conditions, while stopping the toning without changing these.
-Seal them all together: This was my first choice, but I need regular and individual access to the coins.
-Seal them individually in 2x2s: This is far too expensive; each 2x2 costs more than the coins.
Someone asked to what kind of coins I'm referring: well, just recent bronze and copper coins with less than 25 years; most of them uncirculated and with no toning -which I would like to preserve- for example: British pennies and halfs, up to euro cents.
If contact with air is the problem, do you think that individual zip bags would do the trick?
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Bedrock of the Community
United States
17884 Posts |
Individual ziplock bags would cost more than the 2X2's. The real key is to keep them in as dry (low humidity)an environment as possible. Typically the toning reaction is an oxidation-reduction reaction and it requires water (water vapor) to proceed. Eliminate the water vapor and stop the reaction. This is why we recommend controlled microenvironments such as inside a tupperware type container. Silica gel inside such a small enclosed space rapidly "soaks up" the available water vapor, and the near airtight seal of the container keep any more moisture from getting in. You can easily open the container to get access to your coins, but that lets the moisture in again so keep a close eye on the silica gel and recharge (dry) it often. You could keep a spare recharged silica pack in a ziplock bag and swap it for the one in the container each time you get into it. Then recharge the one you took out and store it back in the ziplock.
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Valued Member
Spain
134 Posts |
That was more or less what I was looking for; I think I'll be using the Tupperware with silica, but with zipbags instead of 2x2. I assume the 2x2 would have to be self-adhesive, otherwise the coins would still be exposed; and these are far more expensive than the small ziplocks I'm using (I can get more than 4 bags of 50 for the price of a single 25 SA holders pack). I can also reuse the ziplocks, or put more than 1 coin in, while the SA 2x2s are individual and not reusable.
One question though: do you think that if I simply put the album folders in the Tupperware with the silica would do the trick? This way I could keep the coins ordered and cataloged.
And I just read that to recharge the silica you need to put them 5 hours in the oven; is this the proper way to recharge?
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Valued Member
Spain
134 Posts |
Just realised what you mean by ziplocks; which I confused with regular zipbags. Yes, those are indeed more expensive than 2x2s, but fortunately found a full pack at home.
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Bedrock of the Community
United States
20753 Posts |
I've got Albums of Lincoln Cents, Indian cents, Large Cents and all in Whitman Classic Albums. All are kept in doubled Zip Lock Plastic Bags. First into one, folded over and pushed out as much air as possible. Then that goes into a second one and again, folder over. Been doing that for a long, long time. NONE of any of my Copper coins have toned at all. |
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Valued Member
Spain
134 Posts |
I opted for the same method, but adding the silica gel and without the double bag. The zip locks I found at home are fairly large, so I was able to fit up to 5 album pages in each one; all well packed with a silica bag and the air extracted until it turned into a solid bock.
Now my only worry is whether or not the plastic from the album pages will have any effect on the coins; I'm not even sure they are PVC free, though I bought them just a year ago.
It would be a nice idea to start a thread on this type of tips (if it doesn't exist yet); specially those specific to the restoration and preservation of each metal. For example: the lacquer and acetone tip above, which I'm just about to try.
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Bedrock of the Community
United States
19949 Posts |
Quote:
All are kept in doubled Zip Lock Plastic Bags. First into one, folded over and pushed out as much air as possible. Then that goes into a second one and again, folder over. Been doing that for a long, long time. NONE of any of my Copper coins have toned at all.
Exactly: mo layers = mo betta I take that to another level and put those into tupperware type containers. Lincoln Cent Lover!VERDI-CARE™ INVENTOR https://verdi.care/
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Bedrock of the Community
United States
19949 Posts |
Quote:
Can you protect zinc coins by using clear acrylic laquer? What's the point of using laquer when that in itself will ruin the coin.  |
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Replies: 26 / Views: 5,309 |
Posted 06/23/2013 11:49 pm
