Hey all, I know some have talked in the past of putting proof sets and the like in plastic food bags with gel. Now if one had something too big to put in a bag, say the 25th ase set, could you wrap it in the plastic food wrap? Being "food safe" like the bags, would they be ok to wrap the whole set box and all in that?
Plastic food wrap in and of itself should do no harm to the coins. But leaving the coins in the box sure might do harm to the coins. With harm being defined as unwanted toning.
I don't think I would use plastic wrap. PVC can't be used for containers that may be used for long term food storage but it CAN be used for short term food contact so plastic wrap could contain PVC. If you have something too large for a zip-lock I would look at some of the tupperware type storage containers. Those can come in some fairly large sizes.
One more quick question. Does anyone know the order of the coins in the ogp. Such as which coin was in hole 1,2,3,4,5 from left to right?
Good question. Some quick Googling indicates that the bags are made of polyethylene/nylon. Good news: no chlorine; bad news: some nitrogen, and I'm not sure whether it would form anything potentially hazardous during heat-sealing. I'm guessing not, but I don't have much confidence in the guess. "Vacuuming out the oxygen" sounds great, but most of these materials are quite permeable. They'll protect food in the freezer for weeks, but I don't know how much good they'd do for coins over years. I'd still love to have a room full of storage chests that are trickle-flushed with argon...
If the bag is holding vac, nothing is leaking in, right? And, the machine still vacs while heating the seal. probably removing most any vapor created.
Correct, they are all air permeable. If someone doubts that and you want to see what I mean do a little test. Do you like Oreo cookies ? Next time you get some put them in a Zip-Loc bag, then put them on the shelf in the cabinets, top of the fridge, wherever you keep them, overnight. Next day pick up that bag, do not open it, and smell it. You're gonna smell those cookies. Now if the bag was airtight you wouldn't be able to smell anything. But you can because the air goes right through that plastic. Not out the top, but right through the plastic itself. That's why you can smell the cookies. Same thing will happen with your coins. Zip-Locs and plastic bags are a good idea for people who have no other method, but they are certainly not necessary for proper coin storage. Will they help at all ? Yeah sure they will, but you don't need them, and they won't help enough to matter if you are using proper storage methods to begin with. If you are using a safe, or a Tupperware container to store your coins in, and you use a silica gel pack inside that, then the Zip-Locs aren't going to make any difference. So why bother ?
Nothing's leaking in very quickly. Once upon a time, the product called "Saran Wrap" was made of polyvinylidene chloride (PVdC). PVdC is excellent at blocking oxygen and moisture. Unfortunately, it's kind of messy to manufacture and dispose of, in ways that draw the attention of environmental regulators. So, today, at least in the US and Canada, it's made of low-density polyethylene -- cheap, clean to manufacture, and environmentally benign, but several THOUSAND times more permeable to oxygen. For food, this means that you can still knock over a Saran-sealed bowl without spilling the contents. But if you wrap a slab of meat and put it in the freezer, it'll go bad a lot faster in the new wrap than the old stuff. It's still "air-tight", in the sense that it doesn't have holes. But if you covered a bowl with today's Saran, removed all the oxygen, and then let it sit for a few weeks, you'd find that quite a bit of oxygen had diffused back into the bowl. Think of a latex balloon filled with helium. It's not "leaking"; it holds the helium. But latex is permeable to helium, and so after a day or so, the balloon sinks to the floor. Aluminized Mylar is a lot less permeable, so a shiny Mylar balloon can retain its helium for days or weeks. Oxygen, water vapor and hydrogen sulfide all diffuse through plastic more slowly than helium does -- but they still do make it through eventually. Vacuum-sealing your coins in bags probably protects them to some degree, but not completely, and not forever. Really, though, I'm still talking in generalities. If anybody has actual information about the actual plastic used in these systems -- its thickness, its permeability, how long it really does "hold a vacuum" -- that would certainly trump my speculation.
I will agree on the tupperware not needing ziplocs, but safes tend to be way too air permeable and will fairly quickly saturate the gel you put in there. If you are storing in a safe I would also use tupperwares OR ziplocks with silica gel inside them inside the safe. The safe is for physical protection and the plastic containers with gel in them for chemical protection.
I have never seen any warnings about using PVC for long term food storage. Wikipedia says that food wraps are both PVC and Polyethylene. The two problems with PVC for coins is 1) PVC is a brittle plastic and requires high levels of plasticizers which might leak onto either coins or food and 2) PVC is Poly Vinyl Chloride, which can decompose releasing HCl gas which mixes with any moisture to create hydrochloric acid which is not good for coins (as far as foods go, HCl is the acid in your stomach). I don't think Doug agrees with this, but I am going to test it at home to see if it works here (I know it works in a lab), but if you heat up a copper wire and while it is hot touch some plastic you wish to test, it will burn with a green flame if halogen (chlorine is a halogen) is present.
