Here's the thing with PVC/vinyl. It's not the PVC itself, it's the plasticizers in the PVC. They're volatile and don't stay put. They're what gives a car the "new car smell" (unless you have leather seats, then it's something else). The other thing about plastics is that they're not a true barrier to the degree that something like glass is. They're more like a net or a sieve. Even air-tites are not really air-tight, nor are slabs. Mylar is a very, very good barrier as far as plastics go, maybe 100 times better than "ordinary" plastic, but plasticizers by their design penetrate plastics.
Maybe mylar holders are an effective barrier to green goo, maybe they're not. Maybe somebody else has used vinyl pages for years without problems, but maybe under different environmental conditions where you store your coins, it quickly degrades into the evil green goo.
In theory, PVC could be made with plasticizers that don't harm coins. Maybe newer vinyl coin sheets are made differently. I know phthalates are being phased out in a lot of places because of health concerns. But if there are alternative materials that don't have a history of wrecking coins, I'll go with those any day, even if it means having to replaces pages on occasion because of crappy welds.
Posted 09/05/2011 1:49 pm
