How to Properly Store and Preserve Flattened and Elongated Cents: A Conservationist’s Guide to Toning, Oxidation, PVC Damage, and the Golden Rule of Never Cleaning

I’ve seen too many valuable pieces ruined by improper cleaning or storage. Here’s how to keep yours safe for the next generation.

As a conservationist who has spent decades examining, grading, and preserving numismatic material — from classic Morgan dollars to the wonderfully niche world of elongated and flattened cents — I can tell you that no category of coinage is more vulnerable to well-intentioned destruction than the pieces collectors often dismiss as “novelties.” Flattened cents, elongated cents, and other mechanically altered coins occupy a fascinating corner of numismatics. But they’re frequently mishandled precisely because collectors assume their lower face value means lower risk. Nothing could be further from the truth. A well-preserved elongated Buffalo nickel or a sharply detailed railroad-flattened Indian Head cent can command hundreds of dollars on the open market. A single mistake in storage or cleaning can obliterate that numismatic value overnight.

In this guide, I’m going to walk you through everything you need to know about preserving these unique pieces. We’ll cover the science of toning and oxidation, the silent killer known as PVC damage, how to choose the right holders, and — perhaps most importantly — why you should almost never clean a coin. Whether you’re a member of The Elongated Collectors (TEC), a CONECA enthusiast who specializes in error coins, or someone who just inherited a handful of flattened pennies from a grandparent, this article is for you.

Understanding What Makes Flattened and Elongated Cents Unique

Before we dive into preservation, it’s important to understand what we’re actually protecting. Flattened cents — sometimes called railroad cents — are pennies that have been run over by a train wheel or flattened by industrial machinery. Elongated cents, on the other hand, are coins fed through a rolling mill or pressing machine that stretches the design, often with a custom reverse image rolled into the metal.

Both types are typically made on host coins ranging from Indian Head cents (1859–1909) to Lincoln Wheat cents (1909–1958) to even later Lincoln Memorial cents and, as some modern elongators have experimented with, Buffalo nickels.

Here’s the key point from a conservation standpoint: the mechanical alteration process itself changes the metal’s structure. The copper (or bronze, or zinc) has been stressed, stretched, and sometimes heated. The surface becomes more porous, more reactive, and far more susceptible to environmental damage than an unaltered coin. This means the rules of preservation are even more critical for these pieces than for standard circulation strikes.

The Science of Toning: When Color Helps and When It Hurts

Toning is one of the most misunderstood phenomena in all of numismatics. It’s especially relevant for elongated and flattened cents because the altered surface area often produces dramatic and beautiful color patterns that can significantly enhance — or destroy — a piece’s eye appeal.

What Causes Toning?

Toning is a chemical reaction between the coin’s metal surface and sulfur-containing compounds in the air or in storage materials. On copper coins — which make up the vast majority of elongated and flattened cents — toning progresses through a predictable spectrum:

• Light yellow/gold: The earliest stage, often considered attractive and desirable. This is the kind of luster-adjacent warmth that collectors love.
• Orange/amber: A deeper stage that can add warmth and visual appeal without obscuring detail.
• Red/russet: Moderate toning that many collectors find genuinely beautiful.
• Blue/purple/iridescent: Advanced rainbow toning, often called “terminal toning” when it begins to darken. Stunning in moderation, problematic when it goes too far.
• Dark brown/black: Heavy toning that obscures detail and is generally considered detrimental to both grade and collectibility.

Natural Toning vs. Artificial Toning

In my experience grading elongated cents, I’ve seen both natural and artificial toning — and the difference is usually obvious to a trained eye. Natural toning develops slowly over years or decades. It tends to be even, gradual, and visually harmonious. Artificial toning — induced by exposing a coin to chemicals, heat, or sulfur compounds — tends to be splotchy, uneven, and concentrated in unnatural patterns.

My advice: Never attempt to “enhance” the toning on an elongated or flattened cent. The stretched metal is even more reactive than normal coin surfaces, and artificial toning can quickly become unsightly and irreversible. If a piece has developed beautiful natural toning, consider it a gift from time. Leave it alone. That patina is part of the coin’s story — and part of its value.

Oxidation: The Silent Enemy of Copper Coins

Oxidation is closely related to toning but deserves its own discussion because it represents a more aggressive and destructive form of chemical change. While toning is a surface-level reaction that can actually protect the underlying metal to some degree, oxidation — particularly in the form of verdigris — can eat into the coin’s surface and permanently destroy detail.

What to Watch For

On copper and bronze elongated cents, watch for these warning signs:

• Green spots or patches: This is verdigris — copper chloride or copper carbonate — and it is actively corroding the metal. This is not a “wait and see” situation.
• Powdery white or pale green deposits: Often seen on zinc-based Lincoln cents (post-1982), this is zinc oxide or zinc hydroxide, and it can be extremely destructive.
• Dark, crusty buildup in recessed areas: This may be accumulated dirt, but it can also be a sign of ongoing chemical reactions that are slowly eating away at the strike details.

How to Prevent Oxidation

The best defense against oxidation is environmental control. Keep your elongated and flattened cents in a stable environment with:

• Low humidity: Aim for relative humidity below 50%. Ideally, store coins in a room with a dehumidifier or in a climate-controlled space. This single step will do more for your collection than any other.
• Stable temperature: Avoid attics, garages, and basements where temperature swings are extreme. Thermal cycling accelerates every form of chemical deterioration.
• Minimal air exposure: The less air that circulates around your coins, the slower oxidation will proceed. This is where proper holders become critical — and we’ll get to those shortly.

PVC Damage: The Storage Mistake That Destroys Collections

If I could issue one commandment to every coin collector in the world, it would be this: Never, ever store your coins in PVC-containing plastic holders. I have personally examined collections worth tens of thousands of dollars that were reduced to green-sludged ruins because the owner stored them in soft vinyl flips or PVC-based albums. It’s heartbreaking — and entirely preventable.

What Is PVC and Why Is It So Dangerous?

PVC (polyvinyl chloride) is a common plastic used in many inexpensive coin flips, holders, and albums. Over time, PVC breaks down and releases chlorine gas. This chlorine reacts with the moisture in the air to form hydrochloric acid, which then attacks the coin’s surface. The result is a green, sticky, acidic residue that is extremely difficult to remove and often causes permanent damage.

The damage is especially severe on copper coins — which, again, make up the vast majority of elongated and flattened cents. I’ve seen elongated Indian Head cents that were stored in PVC flips for just two or three years develop irreversible green corrosion that completely obliterated the design details that made the piece valuable in the first place. A rare variety that should have been mint condition in terms of surface preservation was rendered virtually worthless.

How to Identify PVC Holders

Here’s a simple test: if the plastic flip or holder feels soft, flexible, and slightly sticky, it likely contains PVC. Safe plastics for coin storage are:

• Mylar (polyester): Rigid, clear, and chemically inert. This is the gold standard for a reason.
• Polyethylene: Soft but chemically safe. Many modern archival flips use this material.
• Polypropylene: Another safe option, commonly used in coin tubes and boxes.
• Acrylic (Plexiglas): Used in some display cases and is safe for coins.

When in doubt, look for products labeled “archival,” “PVC-free,” or “museum quality.” Reputable brands include Capital Plastics, Lighthouse, and NGC/PCGS holders. The few extra cents per holder are the cheapest insurance you’ll ever buy.

Choosing the Right Holders for Elongated and Flattened Cents

Because elongated and flattened cents are, by definition, non-standard in size and shape, finding appropriate holders can be a real challenge. Here are my recommendations based on years of conservation work:

For Individual Display and Protection

1. Cardboard flips with Mylar windows (2×2 size): These are the workhorse of coin storage. For elongated cents, you may need to use a larger size (such as 2.5×2.5 or even custom-cut holders) to accommodate the stretched dimensions. The Mylar window allows viewing without handling, and the cardboard provides rigidity. Simple, effective, affordable.
2. Archival-quality polyethylene flips: If you prefer a fully plastic flip, make sure it’s labeled PVC-free. These are more flexible and can accommodate odd shapes better than rigid Mylar holders — useful for irregularly flattened railroad cents.
3. Slabbed grading: For high-value elongated or flattened cents, consider having them certified and slabbed by a reputable grading service like NGC or PCGS. Both services will encapsulate elongated coins in their oversized holders, providing the highest level of protection and authentication. This is especially important for rare varieties or pieces with documented provenance — such as those made by well-known elongators like Lord Marcovan. A slabbed coin with a strong grade and clear provenance will always command a premium.

For Bulk Storage

If you have a large collection of elongated cents — as some TEC members do — you may need a more practical storage solution:

• PVC-free coin tubes: Sort your elongated cents by type, date, or theme and store them in labeled tubes. Make sure the tubes are polypropylene or polyethylene.
• Archival coin boxes: Capital Plastics and other manufacturers make boxes specifically designed to hold 2×2 flips in an organized, protected manner. These stack neatly and keep your collection accessible.
• Avoid rubber bands, paper clips, and adhesive labels: These can all cause physical damage or chemical reactions over time. I’ve seen rubber bands literally fuse to coin surfaces. Don’t let it happen to yours.

To Clean or Not to Clean: The Golden Rule of Coin Conservation

This is the section where I’m going to be blunt, because I’ve seen the consequences of bad cleaning decisions too many times: Do not clean your coins. I cannot stress this enough. The vast majority of cleaning attempts — even those done with the best intentions — result in a net loss of value and historical integrity.

Why Cleaning Is Almost Always a Mistake

When you clean a coin, you are removing metal. Even gentle cleaning methods like soaking in distilled water or using a mild solvent will strip away the original surface — including any natural toning, patina, and microscopic detail that contributes to the coin’s grade and numismatic value. On elongated and flattened cents, the situation is even worse because the rolling or pressing process has already thinned and stressed the metal. Aggressive cleaning can literally wear through the design, turning a collectible into a curiosity.

Here are the cleaning methods I’ve seen ruin coins, listed from bad to catastrophic:

1. Rubbing with a cloth or tissue: Creates microscopic scratches (called “hairlines”) that are visible under magnification and dramatically reduce grade. Every swipe removes a thin layer of original metal.
2. Soaking in vinegar, lemon juice, or other acids: Strips away the surface layer and leaves the coin with an unnatural, bright appearance that experienced collectors and dealers immediately recognize as “cleaned.” That harsh, stripped look kills eye appeal.
3. Using commercial coin cleaners (e.g., Dip): These abrasive solutions remove toning and surface metal, leaving the coin looking harsh and artificial. A “dipped” coin is almost always worth less than an uncleaned coin with natural toning. The luster never looks right afterward.
4. Polishing or buffing: The worst offense. Polishing creates a mirror-like surface that is completely unnatural for a coin and is considered damage by every grading service. A polished coin is, for all practical purposes, destroyed as a collectible. I cannot overstate this.
5. Electrolysis or “pencil eraser” cleaning: Sometimes attempted on heavily corroded pieces, these methods are extremely aggressive and should only be performed by professional conservators — and even then, only in rare circumstances where the alternative is total loss.

The One Exception: Professional Conservation

There is exactly one scenario where intervention is appropriate: when a coin is actively deteriorating and needs stabilization. For example, if an elongated cent is developing active verdigris (green corrosion) that is eating into the surface, a professional conservator may perform a controlled treatment to halt the corrosion. This is not “cleaning” in the traditional sense — it’s stabilization, and it should only be done by someone with formal training in numismatic conservation.

Services like Numismatic Conservation Services (NCS) specialize in this type of work. They can stabilize corrosion, remove harmful deposits, and consolidate fragile surfaces without damaging the coin’s originality. If you have a valuable piece that is deteriorating, this is the route to take — not a home remedy. The cost of professional conservation is almost always less than the value it preserves.

Handling Best Practices: Protecting Your Coins Every Day

Even with perfect storage, improper handling can damage your collection. These are the rules I follow myself and recommend to every collector I work with:

• Always hold coins by the edges. Never touch the obverse or reverse surfaces. The oils and acids in your skin can cause permanent fingerprints on copper coins — marks that may not be visible now but will show up years later as dark, corroded spots.
• Work over a soft surface. If you drop a coin on a hard floor, it will dent or scratch. A padded mat or soft towel can prevent disaster. I keep a folded towel on my worktable at all times.
• Wear cotton gloves when handling valuable pieces. While some collectors debate the necessity of gloves (arguing that they reduce dexterity), I believe they are essential for high-grade or historically significant coins. The peace of mind alone is worth it.
• Never talk over an uncovered coin. Saliva droplets are surprisingly corrosive and can leave permanent spots on copper surfaces. It sounds obsessive until you’ve seen the damage firsthand.
• Minimize direct light exposure. Prolonged exposure to sunlight or fluorescent lighting can accelerate toning changes and fade any printed or painted elements on elongated coins. Display cases with UV-filtering glass are worth the investment for prized pieces.

Documenting Your Collection: Provenance and Photography

As a conservationist, I believe documentation is an often-overlooked aspect of preservation. For elongated and flattened cents, provenance can significantly enhance both the historical interest and the market value of a piece. If you know the history of a particular elongated cent — for example, that it was rolled on a specific host coin (like a Buffalo nickel), that it was made by a known elongator, or that it was part of a documented collection — write it down and keep it with the coin.

Photograph your collection regularly. Use consistent lighting and a neutral background. Digital photographs serve as both a record for insurance purposes and a way to track changes in a coin’s condition over time. If you notice that a coin’s toning is darkening or that a new spot of corrosion is appearing, early detection can mean the difference between a simple environmental adjustment and a costly conservation treatment. I photograph my own collection annually — it takes an afternoon and has saved me more than once.

Special Considerations for Different Host Coin Types

Not all elongated and flattened cents are created equal, and the host coin’s composition directly affects preservation strategy. Here’s what I’ve learned from years of working with each type:

• Indian Head cents (1859–1909): Bronze composition (95% copper, 5% tin and zinc). These are highly susceptible to verdigris and benefit most from low-humidity storage. The tin content can produce particularly attractive toning, so avoid any cleaning — you’d be stripping away some of the most beautiful natural patina in all of numismatics.
• Lincoln Wheat cents (1909–1958): Bronze through 1942, then brass (95% copper, 5% zinc) from 1944–1958. The 1943 steel cents are a special case — they are zinc-coated steel and are extremely prone to rust. These should be stored in the driest possible environment and handled with extra care. A rusty 1943 steel elongated cent is a sad sight.
• Lincoln Memorial cents (1959–1982): Brass composition. Similar preservation needs to Wheat cents, though the zinc content makes them slightly more reactive than the earlier bronze pieces.
• Lincoln Memorial cents (1982–present): Zinc core with copper plating. These are the most vulnerable to damage because the zinc core is highly reactive. If the copper plating is breached — which is more likely on an elongated coin due to the stretching process — the zinc will corrode rapidly. Store these in the most controlled environment possible. I treat post-1982 elongated cents as the highest-priority items in any collection.
• Buffalo nickels (host coins for Type 6 elongations): 75% copper, 25% nickel. The nickel content makes these somewhat more resistant to corrosion than pure copper coins, but they are still vulnerable to PVC damage and should be stored accordingly. The nickel also produces a distinctive toning character that’s quite different from pure copper — often more subdued but equally attractive.

Building a Preservation Mindset for the Long Term

Preservation is not a one-time action — it’s an ongoing commitment. The coins in your collection today may be passed down to your children, grandchildren, or fellow collectors for generations. Every decision you make about storage, handling, and display has long-term consequences that compound over time.

I encourage every collector of elongated and flattened cents — whether you’re a member of TEC, a CONECA enthusiast, or simply someone who appreciates the artistry and history of these unique pieces — to adopt a conservation-first mindset. Invest in quality holders. Control your storage environment. Resist the urge to clean. Document your collection thoroughly. And when in doubt, consult a professional. Your future self — and future collectors — will thank you.

Conclusion: Preserving History, One Cent at a Time

Flattened and elongated cents represent one of the most creative and accessible areas of numismatics. From the railroad-flattened Indian Head cents of the 19th century to the beautifully detailed modern elongations rolled on Buffalo nickels and other host coins, these pieces tell a story of American ingenuity, roadside tourism, and the enduring human impulse to transform the ordinary into something extraordinary.

But they are also fragile — more fragile than most collectors realize. The very process that creates them stresses the metal, exposes fresh surfaces to the elements, and makes them more vulnerable to the chemical and physical threats that every coin faces. Without proper care, these pieces can deteriorate rapidly, losing the detail, toning, and historical character that make them valuable.

The good news is that preservation is neither complicated nor expensive. PVC-free holders, a stable environment, careful handling, and the discipline to leave well enough alone — these are the cornerstones of responsible coin conservation. Follow these principles, and your elongated and flattened cents will remain as vibrant and historically significant for the next generation as they are for you today.

As I always tell the collectors I work with: the best thing you can do for a coin is to leave it alone and protect it from harm. Time has already done the hard work of creating beauty. Your job is simply to make sure that beauty endures.

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