The Science of the Strike: A Metallurgical Breakdown of the Kentucky Token and the Copper Alloy Secrets Behind Its Color, Grade, and Eye Appeal

The way a coin ages, tones, and wears is entirely dependent on its metal alloy. Here is a scientific breakdown of this piece.

As a metallurgist who has spent decades studying the behavior of copper alloys in numismatic contexts, I find few topics as fascinating — or as misunderstood — as the relationship between a coin’s metallic composition and the way it presents to the collector’s eye. The recent forum discussion surrounding a beautifully preserved Kentucky token, graded MS64RD by PCGS, offers a perfect case study. This piece, with its population of 2/0 in Red, has sparked a lively debate about color designation, strike quality, and the wisdom of resubmission. But beneath the surface of that debate lies a deeper story — one written in the language of alloy composition, planchet preparation, strike pressure, and metal flow lines. Let me walk you through it.

1. Understanding the Kentucky Token: Historical and Metallurgical Context

The Kentucky tokens of the 1790s represent one of the most historically significant series in early American numismatics. Struck in England and circulated primarily in the Kentucky territory during a period of intense westward expansion, these tokens were produced to address a critical shortage of small change on the frontier. From a metallurgical standpoint, they are fascinating artifacts because they were struck in a period when minting technology was still evolving, and the quality of copper planchets varied enormously from batch to batch.

The typical Kentucky token was struck in a nearly pure copper alloy, often with trace amounts of zinc, tin, and lead — impurities that were difficult to eliminate with the smelting technology of the late 18th century. These trace elements, even in quantities as small as 0.5% to 2%, can have a profound effect on how the coin ages, how it takes a strike, and how its color evolves over two centuries of environmental exposure.

When I examine a piece like this MS64RD Kentucky token, the first thing I consider is not the color label on the holder — it is the underlying metallurgy that produced the surfaces I see. The fact that this coin has survived with wonderfully original surfaces and a total lack of any PVC contamination tells me a great deal about the purity of the original alloy and the conditions under which it has been stored. That kind of preservation is rare, and it immediately elevates the collectibility of the piece in my eyes.

2. Alloy Composition: Why Copper Tokens Tone the Way They Do

The color designation debate — Red versus Red-Brown versus Brown — is, at its core, a metallurgical question. Let me explain why.

The Oxidation Chemistry of Copper Alloys

Pure copper, when freshly struck, exhibits the bright salmon-pink to orange-red color that collectors prize as “Red.” This color is the natural latticed surface of metallic copper with minimal oxidation. However, copper is an exceptionally reactive metal in atmospheric conditions. Over time, it undergoes a predictable sequence of chemical transformations:

• Stage 1 (Fresh Strike): Metallic copper surface — bright red-orange. The crystalline structure of the metal reflects light in the red spectrum. This is the luster that defines mint condition copper at its most visually stunning.
• Stage 2 (Early Toning): Formation of cuprous oxide (Cu₂O) — a thin, transparent to translucent layer that begins to shift the color toward a deeper red-brown. This layer is protective and, in numismatic terms, is often associated with “original” surfaces that carry strong eye appeal.
• Stage 3 (Advanced Toning): Formation of cupric oxide (CuO) and eventually copper carbonate (CuCO₃) — the familiar green patina or the deep brown surfaces we associate with “Brown” designated coins. Once a coin reaches this stage, its numismatic value as a “Red” piece is gone forever.

The rate at which a coin progresses through these stages depends on three primary factors: the purity of the alloy, the environment in which the coin has been stored, and the surface area-to-volume ratio of the metal — which is influenced by the strike quality and the presence or absence of flow lines.

Trace Elements and Their Role in Color Stability

In my experience examining early American copper, I have found that tokens with slightly higher zinc content tend to retain their red color longer than those struck in nearly pure copper. This is because zinc forms a more stable oxide layer that can actually slow the further oxidation of the underlying copper. Conversely, trace amounts of lead — which were common in 18th-century British copper — tend to create micro-galvanic cells on the surface of the coin, accelerating localized corrosion and producing the uneven toning patterns that collectors sometimes describe as “spotted” or “mottled.”

The Kentucky token in question, with its original surfaces and lack of PVC contamination, likely benefited from a relatively clean alloy composition and stable long-term storage. The fact that it has retained enough red to be designated RD — even if some forum members feel it leans RB or even BN — speaks to favorable metallurgical conditions throughout its 230-year lifespan. That provenance of careful preservation is something I always weigh heavily when assessing a piece.

3. Planchet Preparation: The Foundation of a Quality Strike

Before a single die ever touches a planchet, the groundwork for the coin’s final appearance has already been laid. Planchet preparation in the 18th century was a far cry from the precision processes used at modern mints, and understanding this is critical to evaluating any early American copper piece.

Rolling, Cutting, and Annealing

The copper strip from which planchets were cut was produced by passing ingots through rolling mills — often hand-operated or horse-powered in the 1790s. The resulting strip would have had variable thickness, and the annealing process (heating the metal to relieve internal stresses from rolling) was inconsistent by modern standards. Planchets cut from over-annealed strip would be softer and take a different strike than those cut from under-annealed, harder strip. These subtle differences in planchet preparation can mean the difference between a sharp, well-defined piece and a mushy, indistinct one.

When I examine a Kentucky token with a strong, well-defined strike — as the forum poster describes this piece — I look for evidence of good planchet preparation:

• Even thickness across the planchet: Visible in the uniformity of strike across both obverse and reverse.
• Clean, concentric flow lines: Indicating proper annealing and a well-prepared surface.
• Absence of laminations or porosity: Defects that would indicate impurities or gas pockets in the original copper strip.

The fact that this token shows wonderfully original surfaces with no mention of planchet flaws suggests that it was struck from a well-prepared blank — a relatively uncommon occurrence for 1780s–1790s British token coinage, where quality control was often secondary to production speed. Finding a piece like this, free of the typical planchet issues that plague the series, is one of the reasons its numismatic value runs so high.

4. Strike Pressure and Metal Flow: Reading the Coin Like a Metallurgist

This is where my expertise as a metallurgist becomes most directly relevant to the collector. The strike of a coin is, fundamentally, a story about how metal flows under extreme pressure. Understanding this process can tell you more about a coin’s authenticity, quality, and even its potential for regrading than almost any other single factor.

How Strike Pressure Affects Surface Appearance

When a planchet is struck between two dies, the metal flows outward from the center of the coin toward the rims, filling the recesses in the dies. The amount of pressure applied determines how completely the metal fills those recesses — and this has a direct impact on the coin’s color and surface texture.

A well-struck coin will exhibit:

1. Sharp, well-defined design elements: Every letter, every star, every detail of the standing figure on the Kentucky token will be crisp and fully formed. This is where the artistry of the engraver meets the physics of the press.
2. Even color distribution: Because the metal has flowed uniformly, the surface oxidation will be more consistent across the coin. Uneven color on early copper is often a strike problem, not an aging problem.
3. Visible flow lines under magnification: These are the microscopic ridges and valleys created as the metal flowed across the die surface. They are the numismatic equivalent of a fingerprint — unique to each coin and impossible to counterfeit. I consider them one of the most reliable indicators of authenticity.

A weakly struck coin, by contrast, will show incomplete design details, uneven color (because the metal did not flow into all areas of the die), and a “flat” or “dull” appearance that is often mistaken for wear but is actually a strike deficiency. I have seen collectors pay premiums for coins that they believe are high-grade, when in reality the flatness they are seeing is a product of insufficient strike pressure, not mint-state preservation.

Metal Flow Lines: The Hidden Story

One of the most underappreciated aspects of early American copper is the pattern of metal flow lines visible under magnification. These lines, which radiate outward from the center of the coin toward the rim, are created as the planchet metal is forced into the die cavities during striking. In a well-struck Kentucky token, these flow lines should be:

• Concentric and symmetrical: Indicating even pressure distribution.
• Uninterrupted by surface disturbances: No cleaning marks, scratches, or PVC damage should cut across the flow lines.
• Consistent with the design: The flow lines should follow the natural contours of the design elements, not fight against them.

The forum poster’s observation that this coin has wonderfully original surfaces is consistent with what I would expect to see in a piece with undisturbed metal flow lines. This is a strong indicator that the coin has not been cleaned, altered, or improperly stored — all of which would disrupt the natural flow pattern and leave visible evidence under magnification. For me, undisturbed flow lines are one of the single most important factors in determining whether a coin’s eye appeal is genuine or manufactured.

5. The Color Designation Debate: A Metallurgist’s Perspective

Now let us address the elephant in the room — or rather, the elephant in the holder. The forum discussion reveals a significant disagreement about whether this Kentucky token deserves its RD (Red) designation, with several experienced collectors suggesting it looks more like RB (Red-Brown) or even BN (Brown). As a metallurgist, I find this debate both understandable and instructive.

Why Color Designations Are Inherently Subjective

The PCGS color designations for copper coins — RD, RB, and BN — are based on the percentage of original red color visible on the coin’s surface. While PCGS has published general guidelines (typically, RD requires approximately 85–100% original red, RB requires 15–85%, and BN is 0–15%), the actual determination is made by human graders evaluating the coin under controlled lighting conditions.

Several metallurgical factors can complicate this assessment:

• Lighting conditions: The angle and color temperature of light can dramatically affect how red a copper surface appears. A coin that looks RD under warm incandescent lighting may appear RB under cool fluorescent light. I always examine copper under multiple lighting sources before forming an opinion.
• Surface texture: A well-struck coin with strong flow lines will reflect light differently than a weakly struck coin with smooth, flat surfaces — even if the actual oxidation state of the metal is identical. This is one reason why strike quality and color designation are so deeply intertwined.
• Alloy variation: Two coins struck from different batches of copper strip may have different baseline colors, even when freshly struck. One batch might produce a bright orange-red, while another produces a deeper, more brownish-red. This is a critical consideration for 18th-century tokens, where alloy consistency was essentially nonexistent.

The “Wider Birth” Theory for 18th-Century Tokens

The forum poster raises an excellent question: “Is there just a much wider birth given to 18th-century tokens such as this one when TPGs assign RD vs RB?” In my experience, the answer is yes — and there is a metallurgical reason for it.

Eighteenth-century tokens were struck under far less controlled conditions than modern coins. The alloy composition varied from batch to batch, the planchet preparation was inconsistent, and the strike pressure was often lower than what we see in modern minting. All of these factors mean that the “baseline” color of an 18th-century token is inherently more variable than that of, say, a modern Lincoln cent.

As a result, graders at the major TPGs have historically applied a somewhat more lenient standard when assigning RD designations to early American copper. A coin that might be called RB if it were a 20th-century piece might receive the RD designation in an 18th-century context, simply because the graders understand that the original color of the piece was likely different from what we would expect in a modern coin. Whether this practice is fair or consistent is a matter of ongoing debate, but from a metallurgical standpoint, it reflects a genuine reality about how these coins were made.

6. The Regrade Question: Metallurgical Risk Assessment

The forum poster’s dilemma — whether to resubmit the coin for regrading or simply request a new holder — is one that I am frequently asked to advise on from a metallurgical perspective. Let me lay out the considerations.

The Risk of Color Downgrade

Several forum members have noted that the coin may have “turned in the holder” — meaning that its color has shifted since it was last graded. This is a well-documented phenomenon in copper numismatics, and it has a clear metallurgical explanation.

Even inside a sealed holder, trace amounts of moisture and atmospheric gases can interact with the coin’s surface over time. The plastic composition of older holders (particularly those containing PVC or other volatile compounds) can accelerate this process. However, even in modern, PVC-free holders, the natural oxidation process continues — albeit at a much slower rate. Copper never truly stops reacting with its environment.

If this coin was graded RD several years ago and has since shifted toward RB or BN, a resubmission could result in a color downgrade. The forum poster’s strategy of requesting a minimum grade of 64+ RB is a sound one — it acknowledges the possibility of a color shift while protecting the grade and seeking the more accurate designation. I have seen too many collectors gamble on regrades only to watch a rare variety lose its color designation and a significant portion of its numismatic value along with it.

The Metallurgical Case for Reholdering Only

Alternatively, the poster could request a simple reholdering — a new holder with the same grade and designation, without a full regrade. This approach carries less risk of a downgrade but also offers no opportunity to correct what the poster believes may be an inaccurate color designation.

From a metallurgical standpoint, I would advise the following:

1. Have the coin examined under controlled lighting by an experienced copper specialist before making any decisions. A qualified numismatist with a metallurgical background can assess the coin’s oxidation state and provide an informed opinion on whether the RD designation is defensible. This single step can save you from a costly mistake.
2. Consider the coin’s alloy composition. If the piece shows evidence of a higher-purity copper alloy — bright, even color; strong flow lines; minimal surface porosity — it is more likely to retain its RD designation on resubmission. The metallurgy is working in your favor.
3. Evaluate the storage history. If the coin has been stored in a stable, low-humidity environment, the risk of further color shift is minimized. Provenance matters here — a coin with a documented history of careful storage is a safer bet for resubmission than one with an unknown past.

7. Actionable Takeaways for Buyers and Sellers

Whether you are considering purchasing a Kentucky token, evaluating a piece in your own collection, or preparing a coin for resubmission, here are the key metallurgical factors to keep in mind:

For Buyers:

• Always examine the coin in person or through high-quality photographs before purchasing. Color designations on holders are not infallible, and the actual appearance of the coin may differ significantly from what the label suggests. I cannot stress this enough — the label is a starting point, not a final verdict.
• Look for original surfaces. Coins with undisturbed metal flow lines, even toning, and no evidence of cleaning or PVC damage are more likely to maintain their color designation over time. Originality is the foundation of long-term collectibility.
• Understand the premium structure. RD-designated copper coins command significant premiums over RB and BN examples. Make sure you are paying for the actual color of the coin, not just the label on the holder. A coin with genuine eye appeal and original surfaces is worth far more than a piece that simply carries a favorable designation.

For Sellers:

• Invest in professional photography before listing. As one forum member noted, a quality TruView or professional photograph can make a significant difference in how a coin is perceived by potential buyers. Good photography captures the luster, the patina, and the subtle details that convey a coin’s true quality.
• Consider the timing of resubmission. If you believe a coin’s color designation is inaccurate, resubmit sooner rather than later — the longer a coin sits in a holder, the more likely its color is to shift. Time is not on your side with copper.
• Be realistic about outcomes. If multiple experienced collectors have looked at your coin and suggested the color designation may be generous, factor that into your resubmission strategy. Sometimes the smartest move is to enjoy the coin as it is rather than risk a downgrade.

8. Conclusion: The Enduring Appeal of the Kentucky Token

The Kentucky token discussed in this forum thread is, by all accounts, a remarkable piece. With a population of just 2/0 in RD, it represents one of the finest known examples of a series that holds deep historical significance for collectors with ties to the American frontier. The forum poster’s personal connection to Kentucky — through family roots and generational attachment — adds a layer of meaning that transcends the purely numismatic.

From a metallurgical perspective, this coin exemplifies the best qualities of 18th-century copper: a well-prepared planchet, a strong strike that produced clean metal flow lines, and surfaces that have aged gracefully over more than two centuries. Whether it is ultimately designated RD, RB, or even BN, the underlying quality of the piece is not in dispute. The alloy did its job. The strike was true. The surfaces are honest.

The color designation debate, while important for valuation, should not overshadow the more fundamental qualities that make this coin desirable: its historical significance, its originality, its eye appeal, and the skill with which it was struck. As the forum poster wisely noted, “I bought it 100% for eye appeal.” In the end, that may be the most important metallurgical assessment of all — because a coin that speaks to you on a personal level is always worth more than any label on a plastic holder.

For collectors considering similar pieces, I encourage you to look beyond the grade and the color designation. Study the metal. Read the flow lines. Understand the alloy. The science of the strike will tell you more about a coin’s true quality than any TPG label ever could. And if you ever have the chance to hold a piece like this Kentucky token in your hand — a piece with this kind of provenance, this level of preservation, and this much history in its copper — take a moment to appreciate the remarkable journey that metal has taken to reach you.

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