Coin Storage

[Fulvio]

mongrel self adhesives until it decided to open up like a clam

This is why you use staple 2x2's and iron them.

The plastic in the mount is BoPET (aka Mylar). The same stuff they use in Helium balloons (although metallised). So its pretty good at keeping most gasses in/out. If you weld the mount shut with a hot iron, you fuse it into a solid piece which cannot open up, so its far better than either stapled mounts or self-adhesive ones.

All plastics are permeable. And permeability works like this (EDIT: sorry, they don't allow hot-linking. :

http://www.hindawi.com/journals/ijps/2012/302029/fig1/

Without going into the rather complex mathematics (google it), here is a table of some of the more popular food packaging films:

http://www.hindawi.com/journals/ijps/2012/302029/tab2/

Permeability has to do with a number of factors. The size of the gas molecule, the temperature, the type of material (basically the empty space between its molecules), the thickness of the barrier being key factors.

Have a look at the research paper at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1086595/ (3-page PDF at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1086595/pdf/plntphys00497-0030.pdf)

The only thing better than Mylar is PVC, and we all know about that, don't we?

So me, I would use welded 2x2's, and if I wanted an extra level of protection, I'd seal them into (sadly non-transparent) metallised Mylar bags. Which is what they make chip packets out of.. two layers of Mylar with a printed metal core. Or maybe in PolyPropylene pages in a PolyPropylene album, in a sealed bag (even an LDPE ziplock bag should do as this outer layer) if you want to maintain easy access.

[JeffH]

How are you going with the dry nitrogen, sealed container idea?

[Fulvio]

How are you going with the dry nitrogen, sealed container idea?

Pretty much stalled pending a source of the gas. Modifying a commercial oxygen generator would be a couple of grand. Buying bottles just strikes me as a pain in the bum. And my friendly tyre people are all retired so I can't ask them either. Given the reactions I had recently over a damaged tyre (long story) I don't hold much hope of getting any sense out of anyone by just walking in cold. :dodgy:

[r9453]

This is why you use staple 2x2's and iron them.

To be clear, do you kind of iron them around the circular window, avoiding the coin itself?

[Fulvio]

To be clear, do you kind of iron them around the circular window, avoiding the coin itself?

Obviously, yes. If you touch the window, you'll melt a hole in it. And you want a hot iron, some thick fabric underneath and a layer on top. Don't hold the iron in place for too long or the cardboard will yellow. I use a folded up sheet underneath and a coin sack on top.

The Mylar melts @ 260°C. You want something a bit hotter than that so you don't cook the cardboard. Keep the iron moving.

Practice on one that doesn't really matter too much, eh? :angel:

[r9453]

Yep will do, now I wish I didn't give all my spare 2x2s to AJ. I almost can't believe I'm thinking about going back to the 2x2s after replacing well over a thousand of them with SAFLIPs. All that ironing sounds like a bit of a chore.

I still have a mixture of adhesive and staple types. Maybe I need to get rid of the adhesive kind first. Then see if I can rehabilitate the ones that already have staples by ironing them shut and then removing the staples (not sure how that's gonna go). At least I will get to go through my albums once again.

[trout]

Coin storage is an important part of collecting that most of us really don't pay as much attention to as we should.
Most of us are too busy trying to assemble our collections  and not a great deal of thought goes into how we store our collections other than "Does it look nice" and "Is it Cheap".
I have used many systems to store my coins, from tobacco tins and ice cream containers when I first started to Velvet lined wooden slab boxes over the years.
The only thing that has remained constant is that I am always looking for better ways of storing my coins and trying new approaches and techniques.
I still have coins in Bags and ice cream containers and some still in Whitman/dansco folders that I haven't gotten around to doing anything with yet.
When I first decided to organise my collections and put them in albums I bought a few of the dansco push in folders that have the dates and mintmarks conveniently written under the holes the coins were to be placed and I thought that  these would be the "Bees Knees" , Then I started to notice the coins were starting to tone and all of a sudden I noticed my fingerprints all over the coins from where I had pushed them in and touched them whilst looking at them .
This coupled with the problem of the coins falling out when I opened the albums and only being able to view one side of the coin made me rethink what I was doing .
I decided to get some nice soft cover albums That looked fantastic with pages that took 2x2 flips to put my coins in, These were PVC albums and I don't really have to explain what happened there :cray:

I have just recently moved all the coins ( The ones that survived) from the PVC albums into PVC Free archival quality albums that look great and the also come with a slip that holds it all together nicely.
I started off using self adhesive 2x2's for these albums then I discovered saflips which are probably a better option for ease of access and protection for the coin But I still prefer the way the paper flips look and the information I can write on them with ease.
I have also recently started to get some of my coins graded and slabbed in what are now water proof slabs.
This is by far the most expensive option and it takes up considerably more space  to store the coins But it is by far the safest way to store the coins at the moment that I am aware of .
There is also the peace of mind that these slabbed  coins are genuine as well.

For me coin storage and display are an on going thing and who knows what new concepts/techniques will be invented as the years go by and what I am using at the moment may become obsolete compared to the new ideas in the future.

[Basil]

I can't understand all the negativity and urban myths  in Oz. that surround ahhesive 2x2's,they seal properly unlike stapled ones.I have ones that are 40+ years old and no way can you can pry them apart,you have to cut the coin out.I guess from time to time you can get a bad batch or a cheaper inferior product but i've never had a problem providing you buy German sourced ones and don't go larger than 32.5mm.
There is no law that states you can't put a staple in a adhesive 2x2,just to be sure i staple all those that are not stored in a 2x2 album page.My 2c.

[trout]

I have always used Lighthouse Brand 2x2's and I also haven't had any problems with the coming apart or "outgassing" .
I can remember seeing an image of a coin in a self adhesive 2x2 that had sunk into the bottom of the flip But that was standing upright in a shop window subject to UV from the sun and this isn't the way I would choose to store my coins .
They do work out to be a more expensive option to staple 2x2's or saflips though, I think it is just a matter of getting what you pay for :ok:

[ausjack]

Yep will do, now I wish I didn't give all my spare 2x2s to AJ. I almost can't believe I'm thinking about going back to the 2x2s after replacing well over a thousand of them with SAFLIPs. All that ironing sounds like a bit of a chore.

I still have a mixture of adhesive and staple types. Maybe I need to get rid of the adhesive kind first. Then see if I can rehabilitate the ones that already have staples by ironing them shut and then removing the staples (not sure how that's gonna go). At least I will get to go through my albums once again.

I can sell them back to you at a fair price :angel: nah I'm joking you can have them back if you want them :friends:

[trout]

I am in no way saying that the self adhesive 2x2's are a BETTER way of storing a coin because they aren't, A heat sealed saflip offers a lot more protection than a 2x2 ever will .
It is just my personal choice to again use 2x2's because I can write on them, They don't spin around in the flip ( a personal pet hate) and they are aesthetically pleasing.
There is nothing wrong with saflips and I will continue to use them , Just not in my albums :ok:

[autocoupler]

All plastics are permeable. And permeability works like this (EDIT: sorry, they don't allow hot-linking. :

http://www.hindawi.com/journals/ijps/2012/302029/tab2/

Permeability has to do with a number of factors. The size of the gas molecule, the temperature, the type of material (basically the empty space between its molecules), the thickness of the barrier being key factors.

Just trying to better understand what is what on the permeability table.

Are we saying PP film at 13.6 = polypropylene saflip, and Pet Film at 17.8 = Mylar?

If this is correct, and just for arguments sake, can we assume that a polypropylene saflip housed in a PVC environment is capable of passing  more contaminant than a mylar 2X2 would if housed in the same environment?

[trout]

If this is correct, and just for arguments sake, can we assume that a polypropylene saflip housed in a PVC environment is capable of passing more contaminant than a mylar 2X2 would if housed in the same environment?

I would imagine that the difference in the thickness of the saflip material would offer more protection against PVC than the thin mylar film on the 2x2 despite being more porous.

[autocoupler]

I would imagine that the difference in the thickness of the saflip material would offer more protection against PVC than the thin mylar film on the 2x2 despite being more porous.

I would like to think you're right on this. Anyhow, it doesn't really matter as I've converted to saflips and quite happy with that

[Fulvio]

Are we saying PP film at 13.6 = polypropylene saflip, and Pet Film at 17.8 = Mylar?

Yes.

If this is correct, and just for arguments sake, can we assume that a polypropylene saflip housed in a PVC environment is capable of passing  more contaminant than a mylar 2X2 would if housed in the same environment?

I do hope this is a rhetorical question.

The ability of molecules to pass through a solid depends on the space between the solid's molecules. So while material A may have a finer structure, material B which has a looser structure may be much thicker, slowing down the passage. I would think A would have the advantage for large molecules which could not pass through at all. With B, its just a matter of time.

Consider a Helium-filled metallised Mylar balloon. It holds the gas in very well. Much better than any other material. But over a couple of days, the Helium will leak out. That can't be stopped. However once it reaches atmospheric pressure, the contents of the balloon will still be Helium, because the larger molecules in the air won't pass into the balloon. Make sense?