Verdigris and PVC Damage: A Conservator’s Environmental Damage Analysis of the 1883-S Morgan Silver Dollar

Improper storage is the true enemy of our hobby. I’ve seen it destroy the eye appeal of otherwise magnificent coins, and I want to walk you through exactly how environmental damage—specifically to a silver-copper alloy like the 1883-S—takes its toll. More importantly, I want to highlight the damage inflicted when well-meaning collectors attempt to reverse it without proper training or materials.

Recently, I was asked to examine an 1883-S Morgan Silver Dollar—a coin with significant historical weight. Minted at the San Francisco Mint during a year that produced some of the most sought-after Morgans in the entire series, this particular specimen presented a complex conservation puzzle. It featured a visible planchet flaw (a slag inclusion) on the reverse, coupled with evidence of previous, poorly executed “improvement” attempts. What followed was a textbook case study in how environmental damage and improper chemical intervention can compound one another, leaving a coin in a far worse state than nature alone would have produced.

In this article, I’ll walk you through my analysis as a conservator. I’ll break down the environmental and chemical damage visible on this coin, the interplay between original planchet defects and human-caused surface interference, and what any collector—buyer or seller—should understand before attempting conservation on a coin of this caliber.

The 1883-S Morgan Silver Dollar: Historical and Metallurgical Context

Mint Mark, Mintage, and Metal Composition

The 1883-S Morgan Silver Dollar carries the “S” mint mark for the San Francisco Mint, which struck approximately 6,736,000 examples that year. Composed of 90% silver and 10% copper—the standard alloy for U.S. Morgan and Peace dollars of the era—these coins are particularly susceptible to a range of environmental degradation pathways. That 10% copper is the primary driver of tarnish, oxidation, and the dreaded “bronze disease” that can plague silver-copper alloys when exposed to improper storage conditions over decades. When I look at the provenance of these coins, I always keep an eye on how that metal composition interacts with its environment.

In my experience grading and conserving Morgans, the 1883-S occupies a fascinating niche. It isn’t as rare as the 1893-S or the 1889-CC, but it’s far from common in higher Mint State grades. A gem example (MS-65 and above) commands significant premiums, and even lower Mint State specimens in the MS-60 to MS-63 range are actively traded. This economic reality is precisely why collectors are tempted to “improve” damaged examples—and why understanding the risks is so critical. If you ever stumble across a raw example, you’re looking at a coin whose numismatic value hinges entirely on its preservation.

Why the 1883-S Attracts Conservation Interest

The coin’s relatively high mintage compared to key-date Morgans means that raw (ungraded) examples surface regularly in the marketplace. Many arrive from estate collections, old tin-type storage, or—all too often—PVC-containing flips and holders that have been in contact with the coin’s surfaces for years. My first question when evaluating any Morgan for conservation potential is always: What environmental factors has this coin been exposed to, and what has anyone already done to it?

Identifying the Damage: Planchet Flaw vs. Environmental Interference

Recognizing Slag Inclusions and Planchet Defects

The visible mark on the reverse of this 1883-S—between “ICA” and the leaves of the wreath—was correctly identified by experienced forum participants as a planchet flaw, likely a slag inclusion or drift mark. In my professional assessment, slag inclusions occur when non-metallic residues from the minting process become trapped in the planchet before striking. These are not post-mint environmental damage; they are mint-state defects present from the moment the coin was struck.

However, the critical distinction for any collector is this: a planchet flaw is original; the damage surrounding it may not be.

On this coin, the area around the inclusion exhibited a cloudy, discolored halo that extended well beyond the physical boundaries of the flaw itself. This halo is the telltale sign of secondary environmental damage—likely a combination of chemical residue from a prior conservation attempt and oxidation driven by the disruption of the coin’s protective patina layer. That halo completely destroys the coin’s eye appeal.

The “Cloudy” Surface: Oxidation and Chemical Residue

Multiple forum contributors noted that the surfaces of both sides of the coin appeared “cloudy and unoriginal,” not just the area immediately surrounding the flaw. This cloudiness is consistent with a phenomenon I encounter regularly in my conservation work: oxidation haze caused by improper chemical treatment. When a coin is subjected to dipping, wiping, or solvent application without precision, the acetic acid or other reactive compounds can etch the surface microscopically, creating a frosted, lackluster appearance that no grading service will mistake for original Mint State surfaces.

In this case, the cloudiness suggests that someone attempted a localized chemical treatment—possibly an acetone dip or a solvent wipe—to address the visible slag inclusion or the discoloration around it. The problem is that acetone, while useful for removing PVC residue and certain organic contaminants, does nothing to address metallic inclusions or planchet flaws. Worse, if applied aggressively (such as with an acetone-soaked q-tip rubbed repeatedly), it can disturb the coin’s natural surface oxidation in ways that create irreversible color differentials. I’ve seen this kill the luster of a coin permanently.

The Chemistry of Coin Doctoring: Acetone Dips, PVC Residue, and Surface Interference

Acetone Dips: A Double-Edged Sword

Let me be unequivocal about acetone in conservation: it is a legitimate tool in my workshop, but it is not a “fix-all.” Acetone is excellent for:

• Dissolving PVC plasticizer residue left behind by cheap coin flips and holders
• Removing organic adhesives and sticky residues from improper storage
• Cleaning surfaces before a more targeted conservation treatment

However, acetone is not a polishing agent, and it does not remove metallic inclusions, planchet flaws, or slag marks. When a collector uses acetone to try to “clean up” a visible defect, the result is typically a coin with a clean but chemically disrupted surface—one that may show color variance, micro-pitting, or a “washed out” appearance that TPG graders will flag as “improved” or “details” rather than original.

On our 1883-S, the evidence strongly suggests that acetone or a similar solvent was applied to the area around the slag inclusion. The residue pattern—a lighter brownish discoloration with dark streaks adjacent to the flaw—is consistent with a localized chemical treatment that disturbed the natural toning and surface chemistry of the coin.

PVC Plasticizer Damage: The Invisible Enemy

Even if the coin had never been “improved,” it almost certainly suffered from PVC plasticizer damage during its storage life. PVC (polyvinyl chloride) is the enemy of numismatics, and I cannot stress this enough in any conservation analysis. When a coin sits in a PVC holder, flip, or tube for extended periods—especially in warm or humid environments—the plasticizer molecules migrate from the plastic onto the coin’s surface.

The damage manifests as:

1. Hazy, milky discoloration that can appear across the entire surface
2. Sticky or tacky residue that bonds to the metal at a molecular level
3. Etching and pitting where the plasticizer chemically reacts with the silver-copper alloy
4. Disrupted toning patterns that destroy the coin’s aesthetic appeal and market value

In my experience, PVC damage on an 1883-S Morgan is virtually guaranteed if the coin spent any meaningful time in raw storage—particularly in the soft, flexible flips that were standard in mid-20th century coin collecting. The fact that this coin shows cloudiness across both sides, not just the flaw area, is consistent with long-term PVC exposure. Any collectibility is severely hampered when PVC leaves its mark.

Oxidation and Toning Disruption

Morgan Silver Dollars develop their most desirable toning through a slow, natural oxidation process that occurs when the coin is stored in controlled environments—ideally, in non-reactive holders at stable humidity levels. The 1883-S, like all Morgans, is capable of producing spectacular rainbow toning when this process is allowed to occur undisturbed.

Chemical intervention—whether acetone dipping, abrasive cleaning, or the application of “coin shine” products—interrupts this natural oxidation. The result on our 1883-S is a surface that looks artificially bright in some areas and discolored in others, with no coherent toning pattern. To a grader’s eye, this is the hallmark of a coin that has been “improved” and should receive an “UNC Details” or “AU Details” grade at best—never a straight Mint State grade. Achieving true mint condition requires leaving that patina alone.

Bronze Disease and Silver Alloys: A Cross-Metal Concern

Why Bronze Disease Matters for Silver Collectors

You might wonder why a discussion of bronze disease appears in an analysis of a silver dollar. The answer lies in the copper content of the 90/10 silver-copper alloy. Bronze disease—the cyclical corrosion process driven by copper chloride compounds—can affect any alloy containing copper when exposed to moisture, chlorides, and improper storage conditions.

While bronze disease is most commonly associated with copper and bronze artifacts, the same chloride-driven corrosion cycle can manifest in silver-copper alloys as:

• Lilac or purple discoloration on the surface
• Pitting and active corrosion spots that worsen over time if left untreated
• Powdery residue that indicates active metal loss

On our 1883-S, I did not observe active bronze disease, but the dark streaks adjacent to the slag inclusion could represent early-stage chloride corrosion that was accelerated by the chemical disruption from prior “improvement” attempts. In a coin with long-term PVC or improper storage exposure, this is a real risk that any collector should monitor. Preserving the strike and surface integrity means catching these issues early.

Conservation Ethics: What a Numismatic Conservator Would Do

The Principle of Minimal Intervention

As a conservator, my guiding principle is do no harm. Every intervention carries risk, and the goal is always to stabilize the coin’s condition without altering its surfaces in ways that compromise its integrity or marketability.

If I were presented with this 1883-S Morgan, here is my recommended approach:

1. Full documentation: Photograph the coin under raking light at multiple angles to capture the topography of the planchet flaw and any surface interference.
2. Acetone bath (full immersion, not spot-treatment): If PVC residue is present, a brief full-immersion acetone dip followed by thorough rinsing and drying would be appropriate. This removes the plasticizer without the localized risk of spot-applying acetone with a q-tip, which can create color variance.
3. Do NOT attempt to remove the slag inclusion: The planchet flaw is original and part of the coin’s history. Attempting to physically remove it—through scraping, polishing, or chemical etching—will inevitably cause scratches and surface disruption that will cost the coin its Mint State potential.
4. Stabilize and store properly: After cleaning, the coin should be housed in non-PVC, archival-quality holders—Mylar flips or airtight coin slabs—and stored at stable room temperature
   

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