Vinyl, Unplasticized and PET Coin Flips and Currency Holders
What you Need to Know
Most coin flips currently on the market are made from one of two materials: polyvinyl chloride (PVC) or polyester. Polypropylene based materials are also available, though seldom used due to their lack of rigidity.
Polyvinyl chloride (PVC), most often referred to as vinyl, is the most common material used in coin flips. By the numbers, most flips, notebooks pages and currency holders offered today are made of PVC. However, PVC is considered a poor choice by curators and museums looking for long term storage. In part, this is due to plasticizers found in PVC flips. While plasticizers make the vinyl soft, malleable and easy to handle -- properties many collectors and dealers actually prefer -- they include chemical softeners that, over time, and in large enough concentrations, could contribute to coin surface damage.
There are two basic types of PVC flips on the market today: Plasticized (soft flips), and Unplasticized (the hard or rigid coin flips). Unplasticized flips contain lower levels of chemical softeners than soft vinyl coin flips.
Make no mistake, Unplasticized, uPVC or UN flips are still PVC flips.
There is a widely held misconception about this, so let's repeat: there is no such thing as a PVC free unplasticized flip. An unplasticized flip is merely a PVC flip with less plasticizer, or chemical softener. As a result, unplasticized flips are not only hard and rigid, but considered safer for the long term storage of coins. This is why many manufacturers will refer to unplasticized flips as “Safe for long term storage”, or even "Archival". Ironically, unplasticized flips tend to be less popular among collectors who prefer the feel and durability of a soft flip. Just remember, when it comes to vinyl flips, the harder and more rigid the flip, the safer it is as a storage solution for your coins.
If you really want archival, however, you must abandon PVC all together.
The most common non-PVC archival material used today in called Polyethelyene Teraphalate, or PET. As a member of the polyester family, PET is basically the generic version of Dupont brand Mylar.
Different types of PET are currently on the market for coin flips, and they are not all created equal.
PETG, for example, can contain a coating, additives or UV inhibitors. Worse yet, that coating -- the part touching the coin -- may contain PVC or PP. True museum quality PET, as defined by the Library of Congress requirements, must be 100% biaxially oriented, clear, colorless PET, free of surface coatings, UV inhibitors and all other additives. One quick way to determine if you are using a true PET coin flip is to try to seal it with a conventional heat sealer. If you can heat seal it, it is not pure PET.
Uncoated PET cannot be heat sealed -- it has to be welded using an RF sealer.
Some grading services insist that their customers submit their coins only in PET 2 ½ x 2 ½ style flips.
PET and Mylar are not only Archival Quality and safer than any PVC product, they are also extremely strong when used in films. Guardhouse, for example, uses uncoated, biaxially oriented, additive free PET in the Coretek flip. It’s tough stuff. But it comes with a downside. Uncoated PET scratches easily, and because the seams must be welded, they are more fragile than PVC seals.
Regardless of the type of flip used, the conditions under which a coin is stored are of paramount importance. While toning and tarnishing is a fact of nature, failure to store coins in a stable, dry environment will accelerate the process regardless of the holder you choose.
Anyone familiar with soft PVC flips knows they are quite durable, but be warned they are best used for processing, temporary storage or with common coins. Unplasticized PVC, while safer, is more rigid and not as durable as soft PVC. Pure, uncoated PET, while nearly twice the cost of PVC products, is the only material that can truly be called Archival, or Museum Quality.
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