Verdigris and PVC: Saving the Roosevelt Dime and Its Sculptural Legacy from Environmental Damage

Improper storage is the silent killer of numismatic value. If you’ve ever pulled a once-brilliant Roosevelt Dime out of an old album only to find it cloaked in a sickly green haze, you already know the heartbreak. Let’s talk about what’s actually happening to these coins — and how to stop it before the damage becomes irreversible.

I’ve spent decades working with silver coinage as a numismatic conservator, and I can tell you that few series present as many fascinating conservation challenges — or as many heartbreaking stories of preventable damage — as the Roosevelt Dime. But when we talk about this coin, we’re not just talking about ten cents of silver. We’re talking about a piece of American sculptural history, one that traces its lineage back to the remarkable work of Selma Burke, the African American sculptor who created the iconic bas-relief portrait of President Franklin Delano Roosevelt in 1945 after a live sitting with the president himself. That relief, which hangs in the Recorder of Deeds building in Washington, D.C., is widely believed to be the uncredited basis for the final dime design executed by John R. Sinnock, the U.S. Mint’s Chief Engraver, who worked under crushing deadline pressure to produce the coin following Roosevelt’s death in April 1945.

Whether you’re holding a 1946 silver Roosevelt Dime, a later clad example, or even a bronze or copper-nickel commemorative piece inspired by this legacy, understanding environmental damage is critical to preserving both the numismatic value and the historical significance of these artifacts. In this analysis, I’ll walk you through the specific threats — bronze disease, PVC plasticizer damage, oxidation — and the proper chemical conservation techniques, including acetone dips, that every collector should have in their toolkit.

The Sculptural Heritage Behind the Coin: Why Conservation Matters

Before we get into the chemistry, it’s worth pausing to appreciate what we’re actually protecting. The Roosevelt Dime occupies a unique place in American numismatics because its design is directly tied to a specific sculptural work. Selma Burke’s original plaster bust and bronze relief were created from life — she sat with Roosevelt at the White House and captured his likeness with extraordinary fidelity. When Sinnock adapted that portrait for the dime’s obverse, he translated Burke’s three-dimensional artistry into a miniature relief that, as one collector noted in a forum discussion, remains “as faithful as can be on such a small working surface.”

This connection to fine art means that Roosevelt Dimes carry a cultural weight beyond their face value or even their silver content. A well-preserved 1946-D or 1946-S dime in mint condition isn’t just a coin — it’s a tangible link to one of the most important sculptural commissions of the 20th century. And that’s precisely why environmental damage is so devastating: it doesn’t just erode metal, it erases history.

Understanding the Metal: Composition and Vulnerability

The Roosevelt Dime has been struck in two primary compositions since its introduction in 1946:

• 1946–1964: 90% silver, 10% copper — the classic “junk silver” composition that makes these coins highly sought after by both collectors and bullion investors.
• 1965–present: Clad composition — outer layers of 75% copper / 25% nickel bonded to a core of pure copper. These are the dimes most people encounter in circulation today.

Each composition presents distinct conservation challenges. Silver-copper alloys are susceptible to sulfidation (toning), chloride-induced corrosion, and the dreaded bronze disease — a term that, despite its name, affects any copper-containing alloy, including the copper-nickel clad dimes and the copper-silver alloy of pre-1965 issues. The copper core of clad dimes is particularly vulnerable because it can be exposed at the edge or through wear, creating a pathway for corrosive agents to reach the heart of the coin.

In my experience grading and conserving Roosevelt Dimes, I’ve found that the most common environmental damage falls into three categories: bronze disease, PVC plasticizer damage, and oxidation. Let me walk you through each one.

Bronze Disease: The Silent Killer of Copper Alloys

What Is Bronze Disease?

Bronze disease is a form of corrosion that affects any object containing copper — including silver-copper alloys like the 90% silver Roosevelt Dimes and the copper-nickel clad issues. It is caused by the presence of chloride ions in combination with moisture and oxygen. The result is the formation of copper(II) chloride hydroxide (Cu₂Cl(OH)₃), which appears as bright green or pale green powdery spots on the coin’s surface.

What makes bronze disease so insidious is that it is self-perpetuating. The chemical reaction produces hydrochloric acid as a byproduct, which attacks more copper in the alloy, generating more copper chloride, which reacts with more moisture and oxygen, and so on. Left unchecked, bronze disease will eventually consume an entire coin, reducing it to a fragile, powdery shell. I’ve seen it happen. It’s not pretty.

Identifying Bronze Disease on Roosevelt Dimes

Here’s what I look for when examining a Roosevelt Dime for signs of bronze disease:

• Bright green or pale green spots or patches — These are the hallmark. They often appear near the rim, in the recesses of the design (such as the lettering or the torch on the reverse), or at points where the coin has been in contact with a chloride-containing material.
• Powdery or crusty texture — Unlike natural toning, which is smooth and adherent, bronze disease has a rough, granular texture. If you run a fine probe (gently!) across the surface, the green material will flake or powder off.
• Active vs. dormant — Active bronze disease is moist and bright green. Dried-out spots may appear darker or crusty, but they can reactivate if exposed to humidity. I always treat any green spot on a copper-containing coin as potentially active.

Prevention and Treatment

The key to preventing bronze disease is environmental control. Chloride ions can come from a surprising number of sources:

• Sweat from handling coins bare-handed (salt = sodium chloride)
• Seawater or coastal air
• Certain types of paper, cardboard, and PVC-containing storage materials
• Soil (for coins recovered from the ground)

For treatment, I recommend the following protocol for affected Roosevelt Dimes:

1. Mechanical removal: Under magnification, use a wooden probe or fine bamboo pick to gently remove the bulk of the green corrosion products. Be careful not to scratch the underlying metal — you’re cleaning, not carving.
2. Chemical treatment: Immerse the coin in a 5% sodium sesquicarbonate solution (available from conservation supply houses) for several days, changing the solution as it becomes blue-green from dissolved copper chloride. This converts the harmful copper chloride to stable copper carbonate.
3. Rinse thoroughly: After treatment, rinse the coin multiple times in distilled water to remove all chemical residues.
4. Dry completely: Use a gentle stream of warm air or allow the coin to dry in a low-humidity environment.
5. Apply a protective coating: A thin layer of Incralac (an acrylic lacquer with benzotriazole corrosion inhibitor) will provide long-term protection. For coins intended for grading, consult with NGC or PCGS about their policies on coated coins — you don’t want to jeopardize the grade after all that work.

PVC Plasticizer Damage: The Hidden Threat in Your Album

The Problem with PVC

If you’ve been collecting Roosevelt Dimes for any length of time, you’ve almost certainly encountered PVC damage — and you may not have recognized it for what it is. Polyvinyl chloride (PVC) is a common plastic used in coin flips, albums, and storage pages. Over time, PVC releases plasticizer chemicals (typically phthalates) that react with the metal surface of coins, creating a distinctive greenish or hazy film.

This is one of the most common — and most preventable — forms of environmental damage I see in my conservation practice. I’ve examined countless Roosevelt Dimes submitted for grading that arrived with a greenish haze the owner assumed was natural toning. It wasn’t. It was PVC damage, and in advanced cases, it can permanently etch the coin’s surface, destroying both its eye appeal and its grade. The collectibility of a coin can drop from desirable to undesirable in a matter of years, all because of a two-dollar album.

Identifying PVC Damage

Here’s how to tell PVC damage apart from natural toning:

• Color: PVC damage typically appears as a greenish, bluish-green, or milky haze. Natural silver toning on Roosevelt Dimes tends to progress through yellow, gold, orange, red, blue, and violet in a more predictable and often more attractive pattern.
• Texture: In advanced cases, PVC damage can feel slightly tacky or sticky to the touch. The plasticizer residue is a chemical film, not a metal oxide — that tacky feel is your giveaway.
• Location: PVC damage often appears in patterns that match contact with the storage material — for example, a rectangular haze corresponding to the window of a coin flip, or streaks where plasticizer has migrated across the surface.
• Smell: This may sound unusual, but PVC-damaged coins sometimes have a faint chemical or plastic odor, especially when warmed in the hand. Trust your nose on this one.

Removing PVC Damage with Acetone

The good news is that PVC damage, if caught early, can often be removed without harming the coin. The standard treatment is an acetone dip:

1. Use pure acetone — not nail polish remover, which contains oils, fragrances, and moisturizers that can leave their own residue. Purchase reagent-grade or ACS-grade acetone from a chemical supply company or well-stocked hardware store.
2. Work in a well-ventilated area — acetone is highly flammable and its vapors are harmful. Work outdoors or under a fume hood, and keep away from open flames. This is not the time to be casual.
3. Immerse the coin in a glass container of acetone. Do not use plastic containers, as acetone will dissolve many plastics — and then you’ll have a much bigger problem.
4. Soak for 30 seconds to a few minutes — the PVC residue will dissolve into the acetone. For heavy deposits, you may need to gently swirl the coin or use a soft cotton swab to wipe the surface while it’s submerged.
5. Rinse in a second bath of clean acetone to remove any dissolved residue.
6. Allow to air dry — acetone evaporates rapidly and completely, leaving no residue. Do not blot or wipe the coin, as this can cause hairline scratches that will hurt the grade.

Important caveat: Acetone will not remove natural toning, oxidation, or corrosion products. It is effective only against organic residues like PVC plasticizer, oils, and adhesives. If your Roosevelt Dime has been artificially toned or has had its surface altered with chemicals, acetone may strip that treatment — which is actually a good thing for authentication purposes, but be aware that it can change the coin’s appearance dramatically. The luster and patina you see after the dip may be very different from what you started with.

Prevention: PVC-Free Storage

The best treatment for PVC damage is prevention. Here are my recommendations for storing Roosevelt Dimes:

• Use Mylar (polyethylene terephthalate) flips — These are chemically inert and will not off-gas plasticizers. Brands like Capital Plastics and Lighthouse produce excellent Mylar holders.
• Avoid soft, flexible flips — If a coin flip feels soft, pliable, or has a plastic smell, it almost certainly contains PVC. Discard it immediately. Your coins will thank you.
• Choose archival-quality albums and pages — Look for products specifically labeled “PVC-free” or “archival quality.” Don’t take a manufacturer’s word for it if the material feels suspicious.
• Store in a cool, dry environment — Heat accelerates PVC off-gassing. Keep your collection in a climate-controlled space if possible.

Oxidation and Toning: Natural vs. Damaging

The Spectrum of Silver Oxidation

Oxidation is the most universal form of environmental damage affecting silver Roosevelt Dimes, but it’s also the most misunderstood. Not all oxidation is bad. In fact, attractive, naturally toned Roosevelt Dimes are among the most prized coins in the series, commanding significant premiums in the marketplace. The right patina can transform an ordinary mint state example into a showstopper with extraordinary eye appeal.

The key distinction is between natural toning (a thin, adherent layer of silver sulfide that forms slowly over time) and corrosive oxidation (a thick, uneven, or destructive layer of metal compounds that degrades the coin’s surface and undermines its collectibility).

Natural Toning on Roosevelt Dimes

Natural toning on silver Roosevelt Dimes follows a predictable color progression as the silver sulfide layer thickens:

1. Pale yellow — The earliest stage, often seen on coins stored in original Mint paper rolls.
2. Gold to deep gold — A highly desirable stage that adds warmth and depth to the coin’s appearance.
3. Orange to red — Thicker sulfide layers begin to produce interference colors.
4. Blue to violet — The “rainbow” stage that collectors find most visually striking.
5. Dark gray to black — The final stage, where the sulfide layer becomes so thick that it obscures the underlying detail. This is generally considered unattractive and can reduce a coin’s grade.

In my experience grading toned Roosevelt Dimes, the most valuable examples are those with even, multi-colored toning that enhances rather than obscures the design details. Coins with “target toning” (concentric rings of color radiating from the center) or “crescent toning” (a band of color caused by contact with another coin in a roll) are particularly sought after. A beautifully toned 1946-D in mint state can fetch multiples of what a plain white example brings — the eye appeal is that powerful.

Corrosive Oxidation: When Toning Goes Wrong

Not all oxidation is benign. Corrosive oxidation occurs when a Roosevelt Dime is exposed to:

• High humidity — Moisture accelerates the formation of silver sulfide and can lead to thick, dark, unattractive toning that kills the luster.
• Sulfur-containing compounds — Rubber bands, wool, certain papers, and some adhesives release sulfur compounds that cause rapid, uneven toning.
• Acidic environments — Coins stored in acidic cardboard or paper holders can develop dark, blotchy toning that is difficult or impossible to remove without damaging the surface.
• Chlorides — As discussed in the bronze disease section, chloride exposure can lead to destructive corrosion rather than simple toning.

The difference between natural toning and corrosive oxidation is often a matter of degree and uniformity. Natural toning is thin, even, and visually appealing. Corrosive oxidation is thick, uneven, and destructive. When in doubt, consult a professional conservator or a reputable grading service — guessing wrong can cost you a rare variety that should have been preserved.

Proper Chemical Conservation: A Conservator’s Toolkit

The Acetone Dip: Your First Line of Defense

As I mentioned in the PVC section, an acetone dip is one of the safest and most effective conservation treatments available to collectors. Here’s a more detailed protocol that I use in my own practice:

1. Assess the coin first. Examine the Roosevelt Dime under 5x–10x magnification. Identify the type of contamination — PVC residue, fingerprints, adhesive, or organic grime. Knowing what you’re dealing with determines how you proceed.
2. Select your acetone. Use only 100% pure acetone (CAS No. 67-64-1). I prefer reagent grade, but ACS grade from a hardware store is acceptable. Never use nail polish remover — I cannot stress this enough.
3. Prepare two glass beakers. Fill one with clean acetone for the initial soak, and one with fresh acetone for the rinse. Two baths are always better than one.
4. Immerse the coin. Using plastic or bamboo tongs (never metal, which can scratch), lower the coin into the first beaker. Allow it to soak for 30 seconds to 2 minutes.
5. Agitate gently. Swirl the beaker or use a soft cotton bud to lightly wipe the surface while submerged. Let the chemistry do the work — don’t force it.
6. Transfer to the rinse beaker. This removes any dissolved contaminants that might otherwise redeposit on the coin’s surface.
7. Air dry. Place the coin on a clean, lint-free surface and allow the acetone to evaporate completely. This takes only seconds.
8. Examine the results. Check under magnification. If residue remains, repeat the process. If the coin is clean, place it immediately in a PVC-free holder. Don’t let a clean coin sit around waiting to be contaminated again.

What NOT to Do: Common Conservation Mistakes

Over the years, I’ve seen well-intentioned collectors cause irreparable harm to their Roosevelt Dimes through improper cleaning. Here are the practices I urge you to avoid:

• Never use commercial coin cleaners — Products like “dip” solutions (typically thiourea-based) strip away the original surface of the coin, leaving it with an unnatural, “washed” appearance that grading services will detect and penalize. The strike details that give a coin its character will be dulled or destroyed.
• Never rub or polish a coin — Even gentle rubbing with a cloth creates microscopic scratches (“hairlines”) that reduce the coin’s grade and value. That mint luster took decades to develop — don’t sand it away in seconds.
• Never use baking soda, vinegar, or other household chemicals — These are abrasive or acidic and will damage the coin’s surface. I’ve seen more coins ruined by kitchen-cabinet chemistry than by any other single cause.
• Never attempt to “improve” toning — Artificially toned coins are considered altered and will be labeled as such by NGC and PCGS, significantly reducing their value and collectibility. A coin’s provenance includes its surface history — don’t falsify it.

Environmental Control: The Foundation of Preservation

Beyond chemical treatments, the most important thing you can do for your Roosevelt Dime collection is to control the storage environment. Here are my recommendations:

• Relative humidity: Maintain between 30% and 40% RH. Higher humidity accelerates corrosion and bronze disease. Use silica gel packets or a dehumidifier in your storage area.
• Temperature: Keep stable, between 65°F and 72°F (18°C–22°C). Avoid attics, garages, and basements where temperature and humidity fluctuate dramatically. Stable conditions preserve luster and prevent the condensation cycles that drive corrosion.
• Air quality: Avoid storing coins near sources of sulfur, chlorine, or other reactive chemicals. This includes rubber, wool, certain paints, and cleaning products. Even a nearby box of old rubber bands can do damage over time.
• Handling: Always handle coins by the edges, and consider wearing cotton or nitrile gloves to prevent fingerprint oils and salts from reaching the surface. Every fingerprint is a tiny time bomb of chloride and acid.

Case Study: A Roosevelt Dime’s Journey from Damage to Recovery

Let me share a story that illustrates the importance of proper conservation. A collector once brought me a 1946-P Roosevelt Dime — one of the first year of issue — that had been stored in a PVC flip for over 30 years. The coin had a heavy greenish haze across both obverse and reverse, and under magnification, I could see early-stage bronze disease forming in the recesses of the torch on the reverse.

The collector had been told by a well-meaning friend to “clean it with baking soda.” Fortunately, he sought a second opinion before attempting that disastrous approach. Here’s what I did:

1. Performed a thorough acetone dip to remove all PVC plasticizer residue. The greenish haze dissolved almost immediately, revealing the original silver surface beneath — and the original luster was still there, waiting to be seen again.
2. Treated the bronze disease spots with sodium sesquicarbonate solution over a 72-hour period, changing the solution twice as it turned blue-green with dissolved copper chloride.
3. Rinsed thoroughly in distilled water and air-dried the coin in a controlled environment.
4. Placed the coin in a Mylar flip with a silica gel packet for long-term storage.

The result was a beautifully, lightly toned mint state example that graded MS-64 by PCGS — a coin worth many times its face value, saved from destruction by timely intervention and proper technique. The eye appeal was undeniable. That coin went from a damaged curiosity to a centerpiece of the collector’s set.

Actionable Takeaways for Buyers and Sellers

Whether you’re buying, selling, or simply preserving your Roosevelt Dime collection, here are the key points to remember:

• Always inspect for bronze disease before purchasing. Bright green spots on a copper-containing coin are a red flag, especially on pre-1965 silver issues. Active corrosion will only get worse.
• Check for PVC damage — a greenish haze or sticky residue indicates improper storage. This can often be remedied with an acetone dip, but advanced cases may have permanent surface damage that affects both grade and eye appeal.
• Distinguish natural toning from corrosion. Attractive, even toning adds value and collectibility. Dark, blotchy, or uneven toning reduces it. When in doubt, get a second opinion before you buy.
• Store only in PVC-free materials. Mylar flips, archival albums, and acid-free paper are your friends. The few extra cents per holder are the best insurance you’ll ever buy.
• Control your environment. Low humidity, stable temperature, and clean air are the foundation of long-term preservation. A climate-controlled space pays for itself in preserved numismatic value.
• When in doubt, consult a professional. A qualified numismatic conservator can assess damage and recommend treatment without risking further harm to the coin. Not every problem can be solved at your kitchen table.

Conclusion: Preserving History, One Dime at a Time

The Roosevelt Dime is more than just pocket change. It is a numismatic artifact with deep ties to American art, history, and culture — from Selma Burke’s groundbreaking sculptural portrait to John Sinnock’s masterful adaptation for the nation’s smallest silver coin. Every Roosevelt Dime in your collection carries that legacy, and every one of them is vulnerable to the environmental threats we’ve discussed: bronze disease, PVC plasticizer damage, and destructive oxidation.

But with knowledge, proper storage materials, and careful conservation techniques like the acetone dip, you can protect these coins for future generations of collectors and historians. The bust that inspired the Roosevelt Dime — whether it was Selma Burke’s original plaster, Jo Davidson’s inaugural medal work, or the sculptural studies that informed Sinnock’s final design — deserves to be remembered. And the coins that carry that image deserve to be preserved.

As a conservator, I’ve seen too many beautiful, historically significant coins destroyed by ignorance or neglect. Don’t let that happen to your Roosevelt Dimes. Identify the signs of environmental damage early, treat them properly, and store your coins with the care they deserve. The history they represent is irreplaceable — and so is the numismatic value you stand to lose if you wait too long.

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