You’re at a coin show or a dealer’s shop when you ask to see a coin that’s in a flip, one of those double-pocket, plastic envelopes that so many dealers use to display uncertified coins. When he or she hands you the flip, it seems that the coin is actually stuck to the inside of it.

Some flexing of the soft flip is enough to make the coin break free, and then you see it—that pale green outline of the coin imprinted on the inside of the flip. You, my friend, have experienced a PVC moment.

PVC is short for polyvinyl chloride, a popular and widely used plastic that has countless industrial applications. In most of these applications PVC’s qualities are completely benign. In fact, using this plastic for coin flips is OK, too. Where the problem lies is that such storage is suitable only for the short term, say, less than six months. After that time the chemical softening agent that gives PVC its great flexibility may start to leach out. Over time, this can settle onto a coin and deposit an oily film—that sickly, green slime that leaves an outline of the coin on the flip and adheres to the high points of the coin itself.

Prolonged exposure to PVC deposits in the presence of moisture can actually lead to the formation of hydrochloric acid which permanently scars the coin. In its earlier stages, however, PVC film is removable with proper conservation. Any coin displaying such green, oily film on its surfaces may be submitted to Numismatic Conservation Services, LLC (NCS) for removal of the contaminant.

Using PVC coin holders is perfectly all right for short term storage and display. If a coin hasn’t sold after a few months, the dealer should place it in a fresh flip, but this doesn’t always happen. Collectors should never use PVC products for long term storage, a fact which became abundantly clear when a particular brand of coin album had to replace this plastic in its product line with another, less harmful one about 20 years ago. The damage to the products’ reputation, however, was irreversible, and the company went out of business. Old-time collections still come onto the market in such albums, and they’re not a pretty sight.

So how does one know whether a particular plastic holder is PVC or not? Well, one old test is to hold a copper wire to the flip and expose both to a flame. This will produce a blue-green color which reveals the presence of chloride. NGC and NCS do not recommend burning plastic in this ill-advised game of Mr. Wizard, and there’s a much easier test to determine whether a particular plastic is PVC. Simply twist the flip, for a start. If it bends quite easily and shows no indication of fracturing or creasing, it is almost certainly PVC. This quality is what makes it so useful in the short term storage of coins for sale.

Other types of plastic can mimic this quality to some degree, but only the PVC flips are nearly indestructible in normal handling. Acetate or polystyrene flips offer greater chemical protection, but they have limited flexibility and are intended for one-time service; repeated use will cause them to split, deciding the issue of long term storage right then and there. The most chemically inert plastic flips are also the most rigid—Mylar® is a trade name for a very safe plastic that is used for storing both coins and notes, but it must be handled gently. Mylar® flips can split at their joints and are not recommended for shipping purposes. If you submit coins to NGC or NCS at a show, you may notice that both companies use acetate flips as the best compromise between chemical and mechanical protection.
 

PVC damage is caused by storing coins in soft plastic flips that contain polyvinyl chloride (PVC.) PVC most commonly manifests as a light-to-dark greenish residue, although it can appear as milky or light grey in color. It has a distinctive "plastic" odor which can range from subtle to strong. I recommend treating coins for PVC residue whenever you can smell PVC on them, even if you don't see the greenish residue yet, because if the coin has a plastic stink, the PVC breakdown process has begun. For more information about PVC and what causes it, see What is PVC Damage?

Difficulty: Easy

Time Required: About 10 minutes, including prep and clean-up time.

Here's How:

  1. Put on latex gloves and eye protection. Make sure you have good ventilation, and avoid using the kitchen or any area where an open flame is present. Acetone is a powerful chemical that is extremely flammable. Although acetone doesn't burn the skin (it is a key ingredient in some nail polish removers,) you should avoid unnecessary contact.

  2. Pour a very small amount of acetone into the container. (Don't use plastic because acetone will melt it.) You only need about 1/4 to 1/2 ounce if you use a small drinking glass, or tiny jar. You need only enough to cover the coin by about 1/4 inch.

  3. Gently place the coin with PVC residue into the dish, and swirl the acetone around for about 30 seconds. If both sides of the coin are affected, turn it over and swirl the other side.

  4. Remove the coin and let it air dry. If the PVC residue is still present, continue with Step 5. If the coin is clean, proceed to your next coin, and when finished dispose of the acetone by pouring it into a resealable jar. Never pour acetone down a drain, or let more than a very small amount evaporate. Acetone is considered hazardous and must be handled appropriately.

  5. If the coin still needs further cleaning after swirling (and in my experience, most do,) take a cotton swab (such as a Q-Tip) and dip it into the acetone. Then, using a firm and steady hand, roll the swab across the coin's surface on the PVC-infected areas, taking care not to use any sort of rubbing or abrasive maneuver. If the coin has a lot of PVC residue, you should replace the swab every few "rolls." Keep rolling, using new swabs as needed, until the coin appears clean, and then swirl it again to finish.

Tips:

  1. Never rub the coin with the cotton swab. Use only rolling motions. The slightest abrasion might cause hairlines to the coin's surface.

  2. Sometimes PVC residue can be stubborn and will not respond to rolling. Try soaking the coin in a sealed jar of acetone for 24 hours before attempting the rolling maneuver again. If rolling still fails, try more intensive, higher-pressure "dabbing" (but don't "scrub!") If the PVC residue still doesn't respond (in other words, if the swab isn't picking up anything at all,) your coin may not be cleanable (or maybe it's not PVC residue that you see on the coin.) You could try sending it to NCS for expert conservation.

  3. To prevent future PVC damage, do not store your coins in soft or pliable plastic flips. Use the more inflexible Mylar flips instead. Never store your coins in any kind of plastic containers that have a smell.

What You Need:

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Definition: A flip (see photo) is a small PVC, Mylar, or plastic pocket that folds in half, and is designed to hold one coin. Flips usually measure 2 inches square (when folded), but they also come in 1.5 inch and 2.5 inch sizes.

Usually, the collector or dealer puts a coin in the pocket of one side of the fold over, 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 cardboard 2x2.

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.

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Examples: It is not a good idea to store your coins in plastic flips for longer than a few weeks, unless the flips are made of Mylar, because they can cause PVC damage to your coins.

Definition: A 2x2 (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 2x2 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.

Although 2 inches square (2x2) is by far the most common size, these holders also come in other sizes, including 1.5 inches square, and 2.5 inches square.

The 2x2 holder should not be confused with the flip, which has no cardboard, but two mylar pockets with a paper insert to describe the coin.

Question: What is PVC Damage on Coins?
 
PVC damage on coins is the result of improperly storing coins in soft plastic flips. The PVC chemical in the flips interacts with the metal of the coin, creating a slightly acidic reaction, which causes residual deposits to appear on the coin's surface. Copper coins are most vulnerable to PVC damage, followed by silver, and then gold and platinum.

PVC damage appears as greenish, milky, or grey streaks or haze. In severe cases, it looks like tiny green blobs on the surface of the coin. PVC stands for polyvinyl chloride; it is an additive used in plastics to make the material more pliable and less brittle. In coin collecting, PVC is most frequently encountered in the clear plastic flips in which coins are stored. As a general rule, the softer and more pliable the flip is, the more PVC it contains. The hard, stiff, brittle types of flips (made of Mylar) do not contain any PVC.

PVC residue has a distinctive smell, sort of like the smell you get when you open a cheap plastic toy. In mild cases of PVC contamination, you might not be able to detect the smell, but if you ever smell PVC after removing a coin from a soft plastic flip, even though you don't see contamination on the coin, you should treat the coin for PVC damage anyway as a precaution. Removing PVC residue is simple, but left untreated, it will eventually eat into the surface of the coin. Merely taking the coin out of the offending flip isn't enough; once the PVC cycle has begun, the acidic PVC cycle will continue to degrade the coin's surface until permanent PVC damage results. Reputable grading services will not encapsulate coins with PVC residue on them
 

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