by | Apr 29, 2014 | Numismatics, Resources

The American Numismatic Association (ANA) recommends storing coins in acid-free envelopes or “flips,” which are mylar cases that should not contain PVC, or polyvinyl chloride.

While most collectors understand this, the average person does not…    so here is a little back to the basics to help you out…

Definition: A flip is a small PVC, Mylar, or plastic pocket that folds in half, and is designed to hold one just coin (sometimes people cheat and put one on each side but then you can’t see Obverse and Reverse (Front/Back) at the same time. Flips usually measure 2 inches square (when folded) – THE STANDARD, but they also come in oddball 1.5 inch and 2.5 inch sizes.

Usually, the collector or dealer puts a coin in the pocket of one side of the foldover, and puts a little paper or card, called an insert, in the other pocket which identifies the coin. Flips are most frequently used for ancient coins because the catalog information for ancients will not fit on the standard carboard 2×2.

A 2×2 (also called a 2 by 2) is a two-inch square holder for a single coin, made out of cardboard with a circle cut into the center of it for the coin, and with a mylar covering to protect the coin and hold it in place (see photo). The 2×2 is the standard cardboard coin holder, and the hole is usually sized to fit the coin exactly. The dealer places the coin between the halves (which are usually joined at one end, so that it folds over) and then staples it in place.

Sometimes the flip is cut in half where the fold is, so that you have just a little 3-sided pocket, with the opening across the top, into which the coin is placed.

Getting back to the spirit of this blog today….   the PVC flip is soft and feels nice but over time those horrible chemicals inside will react with the metal on the coin turning the coin into something out of Men In Black…i.e. Green Slime

So the ANA recommends using a mylar flip that will not leech chemicals onto the coin…. yeah stop the madness….  the only downside and not for today is that the mylar is not soft and in simple terms on high end proof coins can add some little scratches onto the coin if they are moved in and out frequently.

If you have any specific questions, as always drop me a note…. make it a great day!

Jonathan Lerner Revised

Jon Lerner

Jon Lerner, Scarsdale Coin president, is a recognized expert in the numismatist field. Jon has spent over 30 years collecting and evaluating coins. He is often sought out by fellow coin collectors for his advice and knowledge of rare coins.


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Scarsdale Coin

Jon Lerner, a renowned figure in numismatics, discovered his passion for rare coins in his Scarsdale, New York upbringing. With a keen eye for quality, he founded Scarsdale Coin in 1985, quickly establishing it as a premier destination for collectors. Beyond dealing, Jon is a respected speaker and prolific writer, sharing his expertise with enthusiasts worldwide. His commitment to integrity and professionalism has earned him admiration throughout the numismatic community. Jon remains dedicated to enriching collectors' experiences and preserving the legacy of rare coins for future generations.