How to Properly Store and Preserve WWI Victory and Participation Medals: A Conservationist’s Guide to Toning, Oxidation, PVC Damage, and Proper Holders

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

As a conservationist who has spent decades examining, cataloging, and preserving military numismatic artifacts, I can tell you without hesitation that World War I Victory and Participation medals represent some of the most historically significant — and most frequently mishandled — pieces in the exonumia collecting world. From the iconic HK-892 and HK-903 so-called dollars to the heavy cast bronze plaques produced in Paris during the war, these pieces carry the weight of history in their metal. And yet, every year, I encounter collectors who have inadvertently destroyed the value and integrity of their WWI medals through well-meaning but catastrophic cleaning attempts, improper storage materials, or simple neglect.

This guide is born from years of hands-on experience — from examining the spectacular uncancelled dies sold between forum members to studying the rare gold HK-902a Victory Medal that once passed through the Steve Tanenbaum pedigree. Whether you own a common looped Victory Medal with ribbon or a one-of-a-kind 15-by-22-inch embossed plaque depicting every branch of the United States military, the principles of proper preservation are the same. Let me walk you through everything you need to know.

Understanding What You’re Preserving: The Materials Behind WWI Medals

Before we discuss storage and handling, it’s essential to understand the metallurgical composition of the pieces we’re talking about. WWI Victory and Participation medals were produced in a wide variety of metals, and each reacts differently to environmental exposure.

Common Metal Types in WWI Medals and Exonumia

• Bronze and Copper Alloys: The vast majority of WWI Victory medals — including the standard U.S. Victory Medal designed by James Earle Fraser and the various so-called dollars like HK-892, HK-893, HK-900a, and HK-903 — were struck in bronze or copper-based alloys. These metals are particularly susceptible to oxidation and toning, which we’ll discuss in detail below.
• Brass: Many participation medals and commemorative pieces were produced in brass, an alloy of copper and zinc. Brass develops its own distinctive patina over time and is vulnerable to a specific form of corrosion known as “dezincification” in high-humidity environments.
• Gold: Extremely rare examples, such as the HK-902a struck in 22-karat gold, exist in the so-called dollar series. While gold is far less reactive than copper or bronze, gold medals can still suffer from surface contamination, improper handling, and storage damage.
• Cast Bronze (High Relief): The heavy cast bronze plaques — such as the R.W. Bock copyrighted 1918 plaque and the massive Paris-produced embossed plaque depicting the allegorical figure of America with the Statue of Liberty — present unique conservation challenges due to their size, weight, and high-relief surfaces that trap moisture and pollutants.
• Mixed Materials: Many WWI medals were designed with attached ribbons, loops, bars, and clasps. The American Saviors of Liberty so-called dollar (HK-903) and the French version Victory of Right (HK-903A) both feature loop-and-ribbon configurations. These mixed-material pieces require special attention because the organic components (ribbon fabric) degrade differently from the metal.

In my experience, the single biggest mistake collectors make is treating all of these materials the same way. A storage solution that works perfectly for a gold medal can actively destroy a bronze plaque. Understanding your specific piece’s composition is the first step toward proper preservation.

Toning and Oxidation: The Collector’s Double-Edged Sword

Few topics in numismatics generate as much debate as toning — the natural chemical changes that occur on a coin or medal’s surface over time. In the world of WWI medals, toning takes on particular significance because of the copper and bronze compositions involved.

What Causes Toning on WWI Medals?

Toning is essentially a thin layer of metal oxide or sulfide that forms on the surface of a coin or medal as a result of chemical reactions with the environment. For the copper-based alloys used in most WWI medals, this process begins almost immediately after striking and continues indefinitely. The color progression typically follows a predictable path:

1. Bright copper/bronze: The original mint luster, seen on freshly struck pieces.
2. Golden-yellow: Early-stage toning that develops within months to years.
3. Rose and magenta: Intermediate toning that many collectors find aesthetically pleasing.
4. Blue and green: Advanced toning that can be beautiful when even and natural.
5. Dark brown/black: Heavy oxidation that may obscure design details.

I’ve examined numerous WWI so-called dollars — including the 1917-dated HK-892 varieties with their distinctive soldier-kneeling-on-ground obverse designs — and the unlisted 1918-dated pieces with their rifle-pointing-at-“R”-versus-“A” die differences. The toning on these pieces tells a story. A naturally toned piece with even, attractive coloration will always command a premium over a piece that has been stripped of its original surface.

Natural Toning vs. Active Corrosion: Knowing the Difference

Here is where conservation becomes critical. There is a fundamental difference between stable toning (a thin, adherent layer of oxidation that has essentially halted) and active corrosion (an ongoing chemical process that continues to eat into the metal). Active corrosion on bronze and copper medals often presents as:

• Bright green spots or patches: These are likely copper chloride or copper carbonate formations, commonly known as “bronze disease.” This is an active, self-sustaining corrosion process that will destroy the medal if left unchecked.
• Powdery or crusty surface texture: Unlike smooth, natural toning, active corrosion feels rough to the touch and can flake off, leaving pits in the metal.
• Uneven, blotchy discoloration: While some uneven toning is natural, sharply defined spots of different colors often indicate localized corrosion.

If you suspect active corrosion on any of your WWI medals — particularly on the larger cast bronze plaques or on pieces that have been stored in humid environments — do not attempt to clean it yourself. Consult a professional conservator. I have seen collectors destroy otherwise valuable pieces by trying to “fix” bronze disease with household cleaners.

PVC Damage: The Silent Killer of Stored Medals

If there is one thing that makes me wince more than anything else when examining a collector’s holdings, it is the discovery of PVC damage. Polyvinyl chloride (PVC) was once a ubiquitous material in coin and medal storage — it was used in flips, holders, albums, and even some early third-party grading slabs. The problem is that PVC is chemically unstable over time.

How PVC Destroys Medals

PVC contains plasticizers — chemical additives that make the material flexible. Over time, these plasticizers break down and release hydrochloric acid and other volatile organic compounds. When a copper or bronze medal is stored in direct contact with PVC, these chemicals react with the metal surface to form copper chloride, which appears as a distinctive greenish, sticky or waxy film on the medal’s surface.

The damage is progressive and, critically, irreversible without professional intervention. I’ve seen WWI so-called dollars — pieces like the HK-900a and the various HK-892 die varieties — that were stored in PVC flips for decades. The green PVC residue had eaten into the fields and design elements, permanently reducing both the aesthetic appeal and the market value of pieces that should have been beautiful examples.

Identifying PVC Damage on Your WWI Medals

Here is what to look for:

• Greenish or bluish-green film: Often with a slightly sticky or greasy feel. This is the hallmark of PVC damage.
• Haze or cloudiness: A general loss of surface clarity that cannot be wiped away.
• Etching or pitting: In advanced cases, the PVC chemicals have actually eaten into the metal, leaving permanent damage.
• Smell: If you open a storage container and detect a sharp, chemical, “vinyl” odor, PVC is likely present and actively off-gassing.

Actionable takeaway: Go through your collection today and remove every medal from any PVC-containing holder. Replace them immediately with archival-quality alternatives (discussed below). This single step can save you thousands of dollars in preventable damage.

Proper Holders and Storage: Building an Archival Environment

Now that we’ve covered what not to do, let’s talk about the right way to store and display your WWI Victory and Participation medals. The goal is to create a stable, inert environment that minimizes exposure to the three primary agents of deterioration: moisture, pollutants, and physical contact.

Individual Medal Holders

For individual medals — whether they are standard-sized so-called dollars like the HK-892 or larger participation medals — the following holder types are recommended:

• Mylar flips (non-PVC): Mylar (polyester) is chemically inert and will not react with medal surfaces. These are the gold standard for individual medal storage. Look for flips specifically labeled as “archival” or “museum quality.”
• Acrylic capsules: Hard acrylic capsules provide excellent physical protection and are ideal for higher-value pieces. They allow full visibility of both sides of the medal without handling.
• Third-party grading (TPG) slabs: As several forum members have noted, having WWI medals professionally graded and slabbed by services like NGC provides both authentication and long-term protection. The NGC Census data for these medals — including the fact that only five looped examples of certain types are currently listed — adds a layer of market transparency. However, ensure that any slab you use is confirmed PVC-free. Modern NGC slabs are archival quality, but older slabs from other services should be verified.
• Cotton or nitrile gloves: Always handle medals with clean, lint-free gloves. The oils and acids from human skin can initiate corrosion on copper and bronze surfaces within months.

Storage for Larger Pieces: Plaques and Trench Art

The larger WWI artifacts discussed in the forum — the 15-by-22-inch embossed plaque produced in Paris, the 8-inch-square R.W. Bock cast bronze plaque, and the 1918 75mm trench art shell casings — present unique storage challenges due to their size and weight.

1. Avoid direct surface contact: Never place a bronze plaque directly on a wooden shelf. Wood off-gasses organic acids that can damage bronze surfaces. Use acid-free tissue paper or archival foam as a barrier.
2. Climate control is essential: Large bronze pieces are particularly vulnerable to humidity fluctuations. Store them in an environment with relative humidity between 30% and 40%. This is low enough to prevent active corrosion but high enough to avoid desiccation of any organic components (such as the wood mount on the large Paris plaque).
3. Dust covers: Use breathable, acid-free fabric covers rather than plastic, which can trap moisture against the metal surface.
4. Display considerations: If you choose to display a large WWI plaque, avoid direct sunlight (which accelerates toning unevenly) and ensure the mounting hardware does not contact the medal’s surface. For the heavy cast bronze pieces, ensure the display surface can support the weight safely — some of these plaques are 3/4 inch thick and extremely heavy.

Ribbon and Clasp Preservation

Many WWI medals were issued with ribbons, loops, and clasps, and as one forum member noted, “the ribbon and the bars add a lot to the interest.” These organic components require their own preservation strategy:

• Never attempt to clean old ribbons. The fabric is almost certainly fragile and will disintegrate if washed or brushed aggressively.
• Store ribbons flat whenever possible. Folding creates permanent creases and weakens the fibers.
• Protect from light: UV radiation causes ribbon colors to fade rapidly. If displaying a medal with ribbon, use UV-filtering glass or acrylic.
• Isolate deteriorating ribbons: If a ribbon is actively deteriorating (becoming powdery or shedding fibers), consider carefully removing it from the medal and storing it separately in an archival envelope to prevent the degrading fabric from staining the metal.

To Clean or Not to Clean: The Cardinal Rule of Medal Conservation

This is the question I am asked more than any other, and my answer is always the same: Do not clean your WWI medals. Let me explain why, and then let me outline the very narrow exceptions.

Why Cleaning Destroys Value

When you clean a medal — whether with a commercial metal polish, a homemade acid solution, or even just vigorous rubbing with a cloth — you are removing metal from the surface. You are stripping away the original patina, the microscopic design details that contribute to grading, and the historical evidence of the medal’s age and provenance.

I have examined WWI medals that were “beautifully cleaned” by well-meaning owners, and the results are always the same: a bright, shiny piece that looks artificial, has lost all of its original character, and is worth a fraction of what an uncleaned, naturally toned example would command. The forum discussion about the looped Victory Medal that was “apparently worn by a World War 1 veteran at some point due to the wear” is a perfect example. That wear is history. It tells the story of a soldier who was proud enough of his service to wear his medal. Cleaning that medal would erase that story.

The Only Acceptable “Cleaning” Methods

There are exactly two circumstances where surface intervention is acceptable:

1. Removing PVC residue: If a medal has been damaged by PVC, the greenish residue can sometimes be carefully removed with a pure acetone soak (not nail polish remover, which contains oils and fragrances). This should be done by an experienced collector or professional, as acetone will also remove any oils from your skin and can affect certain surface treatments. After an acetone soak, the medal should be rinsed with distilled water and thoroughly dried.
2. Stabilizing active bronze disease: If you have identified active bronze disease (the bright green, powdery spots mentioned earlier), the affected area can be treated with benzotriazole (BTA), a chemical corrosion inhibitor that is the standard treatment in museum conservation. This is a specialized procedure and should ideally be performed by a professional conservator.

Beyond these two specific scenarios, leave your medals alone. A dusty medal is infinitely more valuable than a cleaned one.

Environmental Controls: The Foundation of Long-Term Preservation

Even the best holders cannot compensate for a poor storage environment. The single most important thing you can do for your WWI medal collection is to control the climate in which it is stored.

Temperature and Humidity

• Ideal temperature: 65–70°F (18–21°C), with minimal fluctuation. Rapid temperature changes cause condensation on metal surfaces, which accelerates corrosion.
• Ideal relative humidity: 30–40%. Above 50%, the risk of active corrosion increases dramatically. Below 30%, organic components (ribbons, wood mounts) can become brittle and crack.
• Monitoring: Invest in a simple digital hygrometer for your storage area. They cost less than $15 and can save you thousands in preventable damage.

Air Quality

Avoid storing medals in areas with high air pollution, chemical fumes, or salt air. Basements (which tend to be humid) and attics (which tend to have extreme temperature swings) are both poor choices. Interior closets on the main floor of a climate-controlled home are often ideal.

Documentation and Provenance: Preserving the Story Alongside the Medal

One aspect of preservation that is often overlooked is the documentation of each piece’s history and provenance. As we’ve seen in the forum discussion, the stories behind these medals are extraordinary — from Samuel Woodfill’s Medal of Honor (the most outstanding soldier of WWI, as called by General Pershing) to the Grace Banker Victory Medal presentation ceremony that took place 105 years after her return from France.

For each medal in your collection, maintain a written record that includes:

• Acquisition details: Where and when you purchased the medal, and from whom.
• Identification: So-called dollar reference number (HK number), country of issue, date, and any die variety notes. For example, the distinction between the 1917 HK-892 with its flagpole-tips die cracks and the unlisted 1918-dated pieces with their rifle-pointing die differences is critical for proper cataloging.
• Condition notes: Current toning, any areas of concern, and the holder type in which it is stored.
• Historical context: Any information about the medal’s original recipient or the event it commemorates. The forum post about the unlooped versus looped Victory Medals — where the medal without clasps was distributed to troops who served in the U.S. only, the single clasp to those who served overseas but not in battle, and multiple clasps to men who participated in more than one major operation — is exactly the kind of contextual information that adds immeasurable value to a collection.
• Photographs: High-resolution images of both sides, taken in consistent lighting conditions. These serve as both a condition record and a theft-recovery tool.

Special Considerations for Rare and High-Value Pieces

Some WWI medals and exonumia pieces are so rare or so valuable that they warrant additional conservation measures. The gold HK-902a Victory Medal (NGC cert 2688838-001), the one-of-a-kind Paris-produced embossed plaque, and the uncancelled dies discussed by forum members all fall into this category.

For these pieces, I recommend:

• Professional conservation assessment: Have a qualified conservator examine the piece and provide a written condition report with recommendations.
• Custom archival mounting: Rather than generic holders, invest in custom-fitted archival mounts that support the piece without putting pressure on vulnerable areas.
• Insurance documentation: Ensure your collection is properly insured, with current appraisals and photographs on file.
• Sealed archival environments: For the most valuable pieces, consider sealed display cases with inert gas (such as argon) backfilling to eliminate oxygen and moisture entirely. This is museum-level conservation, but for a one-of-a-kind piece, it is justified.

Conclusion: These Medals Are History — Treat Them That Way

The WWI Victory and Participation medals we collect are not merely metal discs. They are tangible connections to one of the most transformative events in human history. When we hold a 1917 HK-892 so-called dollar with its allegorical design, we are holding a piece of the same era that produced the Hello Girls who were denied their Victory Medals for over a century. When we examine a looped Victory Medal with ribbon that was proudly worn by a veteran, we are touching something that connected a real human being to the defining conflict of his generation.

The variety and depth of this collecting area is staggering — from the common looped medals to the unlooped rarities, from the standard bronze issues to the legendary gold strikes, from small-diameter so-called dollars to massive cast bronze plaques. Each piece deserves to be preserved with the care and respect that its history demands.

As a conservationist, my final advice is simple: store smart, handle gently, never clean, and document everything. Follow these principles, and your WWI medals will survive not just for the next generation, but for every generation that follows. The stories they carry — of service, sacrifice, and the enduring human spirit — are too important to lose to a PVC flip or a bottle of metal polish.

Preserve the metal. Preserve the story. Preserve the history.

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