From fancy display trays to more practical capsules, there are so many different options available when it comes to coin storage. A variety of plastic commonly found among these products is polypropylene, a popular choice for many experienced numismatists.
Polypropylene is safe for coins in most cases. It is durable, versatile, and has favorable properties as a chemical barrier, especially compared to some other plastics. However, it can be susceptible to UV damage over time, and its aesthetic value depends on personal preference.
Polypropylene does not function in the same way as other plastics, which could hold the potential to damage your coins. Read on to find out more about why coin storage matters so much, and how to ensure the safety of your precious coin collection.
What Is Polypropylene?
Scientifically speaking, polypropylene is a synthetic, thermoplastic polymer with a high chemical resistance. It is produced by chain-growth polymerization from the monomer propylene.
Polypropylene is also one of the most widely-produced commodity plastics in the world, used to manufacture countless everyday products. Commercial production of the polymer began in the 1950s, and it has grown to become one of the most popular plastics in the world today.
Properties Of Polypropylene
Polypropylene is an extremely versatile plastic, making it the ideal option for creating storage and packaging solutions for a range of products. Impressively durable, polypropylene is shatterproof and has a high melting point, which is why it’s a common choice for microwaveable food storage. Its barrier properties ensure it doesn’t absorb water or have unwanted reactions with other chemicals.
The plastic is translucent, doesn’t color over time and has a low level of electrical conductivity. In addition, polypropylene is both cheap to purchase and comes with good environmental credentials, thanks to its ability to be recycled.
How Polypropylene Is Used With Coins
Polypropylene is used in the manufacture of a wide range of different storage products for coins. To begin with, albums are a popular storage option for coin collectors. Polypropylene can be used to create plastic album pages, which are mostly multi-use with different pockets to hold your coin collection.
Coin capsules may also be made from polypropylene, as well as larger coin tubes and cylinders. Individual coin covers are regularly used during the buying and selling of specific coins, also made of this plastic. Some collectors may choose to utilize a nonspecific, multi-purpose polypropylene storage box for their coins, such as the compartmentalized ones commonly used for craft supplies.
Why Coin Storage Matters
Any numismatist will agree that coin storage matters a great deal. With most storage options, the material encases the coin hermetically, providing constant, long-term contact with the coin. Depending on which material is used, this could have an adverse effect on your collection.
Any storage method you select should be practical to suit your collecting needs, but also safe and secure enough to ensure your coins are not exposed to anything that could make them lose that mint appearance.
Polypropylene vs Other Plastics
Although the properties of polypropylene listed above may seem like standard for plastics to anyone unfamiliar with polymer chemistry, it is very important to know that polypropylene should not be confused with other plastics when it comes to coins.
This is because the variations in chemical makeup and manufacturing methods lead to some plastics being extremely unsuitable for long-term coin storage, thanks to substances they contain and properties they may have.
Polyvinyl chloride (or PVC), for instance, can cause irreversible damage to a coin. The chemicals inside this material can break down chemically, releasing hydrochloric acid which reacts with the metal of the coin. This leaves an unattractive residual deposit on the coin. Also known as patina, this greenish corrosion is very difficult to remove without damaging the coin.
Such patina is highly corrosive, so any marks are likely to spread across the coin if it is kept in an affecting container for long periods of time. Polypropylene does not react with coins in this way. This is why it is mostly considered a favorable option for numismatic storage, especially over other plastics.
Benefits Of Polypropylene Coin Storage
As we have explored above, polypropylene is a durable plastic which makes it an excellent choice for many storage solutions, including for coins! Below, we’ll look at some of the most significant benefits of choosing polypropylene for numismatic purposes.
Safe For Coins
Starting with arguably the most important factor, polypropylene won’t cause an undesirable chemical reaction when encasing your coin. As explained above, the chemical makeup of this polymer will not lead to that unfortunate patina coating on coins you would prefer to maintain in mint condition. This is a huge benefit of polypropylene, compared with other plastics such as PVC.
Presentation
For many coin enthusiasts, ensuring their collection is kept in attractive, secure and displayable storage is of the utmost importance. Polypropylene coin storage sheets are very popular for presentation purposes like these. The translucent material enables the coins to be mostly visible to admirers, whilst still ensuring they are protected from inquisitive handlers!
Similarly, additional sheets can be purchased to house an ever-growing collection, but the lightweight plastic will not add too much unnecessary weight to an album.
Pricing
Thankfully, polypropylene is very reasonably priced, with a pack of coin storage sheets usually costing less than $10. This means coin afficionados can put more money into expanding their collection itself, rather than the need to fund expensive accessories to support the hobby.
Environmental Impact
The environmental impact of the plastic you choose is another highly important factor to consider, and polypropylene is a favorable contender in this category too. Polypropylene is recyclable under most national schemes and, once collected, is melted down into small pellets, which can then be used to create new plastic products.
Drawbacks Of Polypropylene Coin Storage
Of course, polypropylene has its drawbacks, too. Although, in our opinion, there aren’t as many cons as there are pros to this plastic, it is always worth knowing all you can about this polymer as a storage method before you commit to using it.
Presentation
Yes, I know we used presentation as a benefit of polypropylene coin storage. But it could also be a drawback too, depending on your personal preference! Although plastic coin capsules are fairly inoffensive aesthetically, the same can’t always be said for plastic coin album sheets. In fact, many collectors may deem their translucent, plastic appearance as unattractive.
Unless the plastics are completely clear, the detail on the coins may not be completely visible through their pockets, and this wouldn’t suit a collector who takes pride in admiring his coins. Polyester, perhaps, would be more favorable for a collector seeking storage with more clarity.
Identification
If you find an old, rare coin, heavily soiled with oxidation and dirt, and a dealer examines and identifies it for you, you’d want somewhere to write down what the coin is. And what better place to keep note than with the coin itself?
It is not possible to write on polypropylene, which could be another disadvantage to some coin collectors. Particularly for those looking to store their coins for archiving purposes, having the ability to write on a coin’s casing could be especially useful.
UV Damage
The only other drawback worth mentioning for polypropylene coin storage is that the polymer can be subject to UV damage over time. However, unless you are planning on displaying your coin collection in direct sunlight for extended periods of time, this shouldn’t really be a problem. But it is something to be aware of, just in case.
Alternative Storage Methods To Consider
If, after reading this article, you have decided you’d prefer to keep your coins away from plastic storage altogether, we’ve listed a few other options to consider below.
Coin Trays
One of the more elegant coin storage solutions is to use coin trays. Often a wooden or plastic holder with indented holes for placing coins into, these trays are usually covered with a luxurious fabric such as velvet.
Although coin trays are a fancy and attractive display method for coins, they’re not a very practical option for storage. Despite fitting into briefcase-style carriers, the otherwise uncovered coins are unprotected from naturally-occurring elements in the air. This puts the coins at risk of oxidation, and they may develop patina caused by the material lining touching the coin.
Trays vs Capsules
When compared to coin capsules, coin trays take up much more room, and are not even close to being as secure as capsules. If dropped, coins would undoubtedly slide out of the tray, potentially colliding with one another and leading to scratches. If a coin in a capsule were to fall, it would mostly likely stay protected.
With that being said, coin trays may be a good short-term storage solution for temporarily displaying coins, for instance when showing off the collection to other enthusiasts. Coins stored using this method may be easily organized and replaced, with this perhaps being a benefit for traders.
Cardboard
Coin file slips made from cardboard are another option which collectors may consider. They’re cheap, simple, and they’re good for archival purposes thanks to the handy ability to be able to write on the cardboard casing.
However, cardboard coin cases aren’t 100% cardboard! They actually hold an inner slip of plastic – usually polyethylene – into which the coin fits snugly. Although this means that any damage or natural deterioration to the cardboard wouldn’t reach the coin, the regular pros and cons of plastic storage should still be considered.
Is Polypropylene The Right Choice For Your Coins?
Even knowing all of this information, you should always be sure to double-check the methods you are using.
Check Specifications
Before purchasing coin storage accessories, be sure to check the material first! Especially after reading this article, we hope you understand how important a factor your material choice can be when it comes to ensuring the longevity of your coins.
When making a purchase online, most specialist websites will list full specifications for their products, encompassing not only the dimensions and capacity of the box/album/capsule, but also the materials from which it is manufactured. Make sure you check these out before buying.
If you’re shopping at a store, definitely be sure to check the packaging of the product or, if you are unsure, ask a specialist sales advisor for some help. If you still aren’t sure about what’s inside the product you’re buying, it may be best to look elsewhere instead.
Check Your Coins
On a similar note, it is always worthwhile to regularly check your coins for any damage or corrosion. No matter how the coins are stored, it is good practice to carefully check the coins for dents, scratches or developing patina, in order to ensure their condition.
If you notice that a coin you are storing is developing spots of oxidation, it might be best to change how it is stored quickly, to avoid the damage spreading.
Final Thoughts
Polypropylene is a suitable storage option for coins. It is worthwhile to understand the possible risks of chemical reactions between coins and various storage materials in order to avoid unnecessary and unattractive corrosion, and even possible damage to your coins over time.