By Mike Diamond for CoinWeek…
In the February 14, 2022, “Collectors’ Clearinghouse” column in Coin World, I discussed an off-center 1952-D Lincoln Cent that displayed an unfamiliar texture on the unstruck crescent of its obverse face. The coin was initially posted on the Coin Community error coin forum by its discoverer, William McClure. The texture appears as an array of closely-spaced, lumpy, parallel ridges.
Shortly after I submitted my article, a second off-center 1952-D Lincoln Cent with the same odd texture surfaced. Discovered by Keith Christenson, it was posted on the same website. As with the first specimen, the lumpy lines are restricted to the obverse face of the unstruck crescent.
I recently acquired a third off-center 1952-D Lincoln Cent exhibiting the identical texture. However, in this specimen, the texture appears on both faces of the unstruck crescent. On the obverse, the lumpy, parallel ridges cover the entire surface. On the reverse, there is only a single, short ridge located near the outer margin of the unstruck crescent. That ridge is aligned with the ridges on the opposite face.
Evaluating Previous Hypotheses
I considered several explanations in my initial analysis of the first specimen. In many cases, their plausibility suffers in light of these additional two specimens.
While the ridged texture might superficially resemble a lamination error, a close inspection reveals no surface cracking.The ridges show some resemblance to the striated surface of a split planchet. However, any such planchet should be underweight. The weights of all three specimens fall within the normal range for copper-alloy cents. The third specimen is even slightly overweight at 3.27 grams (normal is 3.11 grams).
I considered the possibility that the ridges were the impression of a split blank or split planchet that had been crushed into each of our subject planchets. This could have occurred during a jam in a feeder tube. However, it’s unlikely that such an event would have affected three 1952-D Lincoln Cent planchets and no other planchets from any other time period or denomination. In the case of the third specimen, it’s even more unlikely that both faces of the planchet would have been sandwiched between the striated surfaces of two separate split planchets.
I also considered that this texture was imparted during the rolling out of the cent strip, when a large metal flake detached from the strip’s surface and landed on top of the strip before it made its final pass through the rolling mill. This would be a type of “rolling indentation” error. This diagnosis is unlikely because any blank derived from this section of the strip would be underweight, as this area would be thinner than normal once the overlying flake fell off. For the third specimen, it’s highly improbable that two flakes would have separated from the top and bottom surfaces of the strip, their positions and textures aligning with each other, and then both winding up between the strip and the nearest roller.
New and Discarded Ideas
One hypothesis I didn’t originally consider was that these lumpy ridges could represent occluded gas bubbles. When gas expands just beneath the coin’s surface, it pushes up the overlying metal into a low dome. There are many reasons why this hypothesis fails.
First, an occluded gas bubble should flex when the tip of a toothpick is forcefully pressed into it. None of the ridges on the third specimen flex, suggesting they are solid.
Second, occluded gas bubbles should be largely or exclusively restricted to the struck portion of the coin, as it is the heat generated by the strike that causes the gas to expand. No unexpected lumps are seen on the die-struck surfaces of these 1952-D Lincoln Cents.
Third, gas bubbles this extensive should dampen the coin’s sound. Instead of a dull thud, the third specimen produces a normal ring when dropped on a kitchen counter.
Another possibility is pre-strike damage to the strip that occurred prior to its entering the blanking press. Perhaps a section of the strip was chewed up by the feeding mechanism. However, once again, we would expect to see irregular grooves, not ridges.
I suppose the strip could have been compressed against two surfaces that were themselves chewed up. The device that feeds the strip into the blanking press could have been damaged in such a way as to leave raised impressions on the strip.
It’s also possible that the individual blanks were crushed between damaged or irregular surfaces belonging to an unidentified piece of mint machinery that left them with a parallel array of lumpy ridges. Since the ridges continue onto the planchet’s proto-rim, it’s unlikely that the damage occurred after upsetting. Any resulting expansion in the blank’s diameter would have been corrected as the blank passed through the upsetting mill.Pre-strike crushing damage can transfer a coarse, uneven, or striated texture to a disc. One half of this off-center zinc cent planchet was crushed between two flat surfaces bearing similar patterns of damage. Each surface impressed its pattern of fine parallel scratches into the planchet (Coin World, April 13, 2015).
The Most Likely Scenario
I considered the possibility that the rollers became coated with a lumpy paste that was then stretched out as the rollers squeezed the coin metal strip. The texture of the lumpy paste would then have been transferred to the portion of the strip from which these cent planchets were derived, creating a striated appearance. This hypothesis fails because the lumps on the rollers would have left irregular grooves and pits on the unstruck portions of these 1952-D Lincoln Cents, not ridges.
The most likely explanation is that the rollers themselves were damaged or defective, leaving them with irregular grooves and elongated pits. These would then have been transferred to the strip in the form of elongated, lumpy ridges. Strong support for this hypothesis appears on the reverse face of the third specimen. The unstruck crescent reveals faint parallel lines or ripples that reflect the “grain” of the planchet (generated during rolling) or the direct impression of the rollers. These ripples lie parallel to the single ridge located in the outermost part of the crescent. As noted, that isolated ridge is aligned with the obverse ridges in vertical space.I can’t imagine what could have damaged both rollers simultaneously, if this is indeed damage.
It’s possible that, instead, both rollers were imperfectly cast, machined, or smoothed. However, I think the most likely explanation is that both rollers were composed of poor-quality steel. During use, they experienced exaggerated wear that took the form of irregular grooves and elongated pits.
It’s likely that a significant length of strip ended up carrying this texture and that many blanks were produced from this textured strip. But we only know about it from those coins that were struck off-center.
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