Part XI. Non Errors:

Altered Coins:

Dryer Coins

Definition -This term is used in reference to abused coins that have tumbled around inside of an industrial dryer. The coins tend to get trapped in between the inner and outer tubs of these dyers and then are subject to repeated cycles of being battered against the hard surface in the heated chamber.  The obverse and reverse designs have been pummeled into mush. Some metal has been relocated from the edge and design rim onto the field and peripheral letters in the form of a thin apron. The apron forms a complete ring that lies loosely on each face.  For more information and examples of dryer coins, please see this thread: https://www.coincommunity.com/forum/topic.asp?TOPIC_ID=143863

The images above are of a 1964 Jefferson Nickel.

Images courtesy of Harley Handzel.

Part VI. Striking Errors:

Weak Strikes:

Rim-Restricted First Strike

Definition: A weak strike caused by insufficient die approximation in which the dies are so far apart at their closest approach that they only manage to contact the planchet’s proto-rim.  This error can appear on centered planchets and off-center planchets.

The dies that struck this 1999 Pennsylvania quarter were so far apart that they only managed to strike the planchet’s proto-rim.  This created a halo of design on both faces while leaving the center of the coin unmarked.  Since the inward slope of a strongly developed proto-rim can extend further into the planchet than the design rim, it is possible to get a rim-restricted first strike on a perfectly centered planchet.

This dime was struck approximately 70% off center by excessively spaced dies.  There is a faint trace of Roosevelt’s throat in the field.  Otherwise, obverse design elements are restricted to the proto-rim.  These include his lip, chin, and back of his neck..  Reverse design elements appear exclusively on the proto-rim and include portions of the flame and several olive leaves.  Interestingly, the planchet is pristine, having avoided all tumbling marks that are ordinarily picked up in the annealing drum, chemical rinse bath, riddlers, and other sources of planchet-to-planchet contact.

This dime received two off-center strikes.  It’s not clear whether it is a saddle (tandem) strike.  The off-center strike that is die-struck on both faces is very weak.  In the obverse field, there is a faint trace of Roosevelt’s forehead and crown.  A more strongly struck impression of his brow appears on the proto-rim.  On the reverse, the first three letters of PLURIBUS appears on the proto-rim, with no design elements visible in the field.  The other off-center strike is well-struck, in part because a previously-struck dime was taking up any excess space that may have existed (generating a “mirror” brockage of the obverse design on the reverse face).

Part V. Planchet Errors:

Wrong Planchet and Off-Metal Errors:

Double Denomination Errors:

Struck Over Pre-Existing Wrong Planchet/Off-Metal Error

Definition: A design struck over another design (either domestic or foreign) which was, in turn, struck on the wrong planchet.  Such errors are quite rare, with a significant proportion intentionally fabricated inside the mint.

This state quarter design was struck over a 2000-P nickel design which had been, in turn, struck twice on a cent planchet.  The quarter strike was off-center and has a first-strike brockage of the obverse quarter design on its reverse face.  This error may have had some assistance in its creation.  Photos courtesy of Terry Holcomb.

This 2004 Canadian cent design was struck over a 2004 Papua New Guinea 1 tohea design which had itself been struck on a Fiji one cent planchet.  The coin was cherrypicked from eBay by James Zimmerman, who expended a great deal of time and effort in identifying the host coin design and the original purpose of the planchet.  This seems to be a truly accidental error.  Photos courtesy of James Zimmerman.

This 1983 Canadian cent design was struck on an Israel 10 shekels design which was originally struck on a Canadian 1 cent planchet.  As such, the final strike generated a dual country / double-denomination error but not a wrong planchet error.  This is almost certainly an intentional error because it was struck in-collar.  The original off-metal coin would have to have been resized after the first strike, which would have caused the coin to expand beyond the diameter of the collar.  Photos courtesy of Fred Weinberg.

This 1982 Costa Rica 25 centavos design was struck over an Israel 10 shekels design which had originally been struck on a Costa Rica 25 centavos planchet.  As with the previous coin, the final strike generated a dual country/double denomination error but not a wrong planchet error.  And as with the previous coin, the last strike was in-collar, which would have required resizing of the expanded off-metal 10 shekels.  Photos by Mike Diamond

Part V. Planchet Errors:

Rolling Mill Errors:

Rolled-In Patterns and Textures

Rolled-In Coth Pattern

Definition: Coin metal strip that is rolled against cloth will end up with a checkerboard pattern on one or both surfaces.  This pattern will remain visible in the case of a weak strike or an off-center strike.  Such errors can occur by accident if a mint worker is holding up the sagging end of a length of strip with a protective cloth as the strip is guided into the rolling mill.  The cloth can get trapped between the rollers and dragged into the rolling mill.

This off-center 1965 cent features a rolled-in cloth texture on both faces.  It is possible that a piece of cloth was wrapped around the trailing end of the strip to protect the workers hands.  Photos courtesy of Heritage Auctions.

A second off-center 1965 cent shows a rolled-in cloth pattern on the reverse face.  This and the previous coin are the only known examples of rolled-in cloth patterns (a.k.a. rolled-through cloth errors).  Photos courtesy of Heritage Auctions.

Part VI. Striking Errors:

Skidding Coin Errors

Definition: A weakly-struck coin that is pushed sideways while it is still loosely clamped between the dies.  Affected design elements are smeared or completely scraped off the coin’s surface on both faces.

A skidding coin error can only occur in the context of a weak (low-pressure) strike.  When a coin is weakly struck as the result of insufficient die approximation (the most common cause), it is necessarily held in a weak embrace by the dies, even at the lowest point of the hammer die’s downstroke.  If the coin should be knocked sideways while it is still weakly clamped between the dies, the newly-struck design elements can be smeared or scraped away as the coin is pushed across the two die faces.  Smearing can occur during the final moments of the downstroke, immediately after the hammer die has reached the lowest point of its downstroke, or while the hammer die is lifting off the surface of the coin.

Skidding coin errors should not be confused with skidding die errors (slide doubling, skidding misalignments, design decapitation errors, design ablation errors).  Skidding die errors of any significance are always found on the face struck by the hammer die and are caused by die movement.  Skidding coin errors are bifacial and are caused by coin movement.

This 2017 Malaysia 20 sen coin represents the only known example of a skidding coin error.  The error occurs in conjunction with a 40% off-center, rim-restricted second strike.  The first strike was an uncentered broadstrike that left a deep collar scar on the right side of the reverse face.  Resistance from the stiff collar pushed up a low, thick, vertical flange on the obverse face.  Opposite the flange is an unstruck crescent on the reverse face that lies between the die-struck field and the collar scar.  Before the second strike, minimum die clearance abruptly increased so that, at their closest approach, the dies could only manage to contact the top of the flange and the unstruck crescent during the second strike.  While the coin was clamped between the dies it was pushed or carried sideways.  It’s quite possible that the feeder/ejector provided the necessary force.  The movement seems to have been more of a pivoting action, with the greatest arc of movement toward the south.

On the obverse, the descending limb of the 2 has been grossly smeared in a west-to-east direction (consistent with a clockwise pivot of the coin).  The base of the 2 is also smeared, but not as severely, as it was aligned with the axis of movement.  Letters belonging to the words SEN and MALAYSIA have been completely scraped off.

On the reverse, the five horizontal lines (four solid and one dotted) that lay medial to the arc of circular dots have been modestly distorted by smearing.  These elements were also aligned with the axis of movement.  The flower petal closest to the lowest horizontal line has been grossly smeared.

Part VI. Striking Errors:

Die Alignment Errors:

Forced Misalignments

Definition: The term refers to misaligned die errors that can be linked to a specific circumstance or impact that delivered a vertical or horizontal force to the die.  Forced misalignments are most often connected to horizontal misalignments of the hammer die.

1. Collar clash. When a (temporarily) misaligned hammer die smacks into the beveled entrance the collar or scrapes down along the latter’s working face, it can push the die sideways in the opposite direction.

This 1998-P quarter displays a horizontal misalignment of the hammer (reverse) die toward the northwest.  At the opposite pole, the design rim shows the characteristic serrations of collar clash.  The impact of the hammer die against the collar could have nudged it in the opposite direction.

2. Stiff collar error. When a slightly uncentered planchet is driven into a collar frozen in the “up” position, the shear forces transmitted through the planchet can nudge the hammer die sideways.

This 1997-P quarter features a stiff collar error in the southwest quadrant of the reverse face, which was struck by the hammer die.  The hammer die is misaligned toward the northeast.  The slightly uncentered planchet was driven all the way into a collar that was fully deployed and frozen in the “up” position.  The shear forces generated at the site of the stiff collar error may well have nudged the hammer die in the opposite direction.

3. Die attrition error.  When a (temporarily) misaligned hammer die smacks repeatedly against the beveled entrance of the collar, the edge of the field portion of the die (and often the rim gutter) is worn away.  The repeated impacts can drive the hammer die in the opposite direction.

This 1996 cent features (1) a die attrition error in the northeast quadrant of the obverse face, (2) a stiff collar error at the same location, and (3) a horizontal misalignment of the hammer (obverse) die toward the southwest.  The repeated impacts of the hammer die against the beveled entrance of the collar wore away the field portion of the die so that the internal margin of the planchet’s cupped, unstruck crescent skirts the top of TRUST.  These impacts probably nudged the die toward the southwest, aided by the shear forces generated by the stiff collar error.

4. Indents and partial brockages.  These can nudge a die sideways, especially when combined with a stiff collar.  When an unstruck planchet or a previously-struck coin intrudes between the hammer die, an underlying planchet, and a fully deployed collar frozen in the “up” position, powerful shear forces are generated.  These can nudge the hammer die sideways.  While in-collar indents and partial brockages can be found in just about any location relative to a misalignment, they’re most often seen opposite the direction of movement.

This undated copper-alloy cent features a horizontal misalignment of the hammer (obverse) die toward the northwest.  An in-collar indent is seen in the southeast.

Part VI. Striking Errors:

Collar Shimmy

Definition: Deformed or smeared reeding that is generated while a newly-struck coin is still pinned between the dies.  The abnormal reeding is caused by rapid oscillation of the collar, sometimes supplemented by horizontal movements.  The newly-struck coin may have been initially struck within the collar, or partly or completely outside the collar, with the collar “popping up” and shimmying while the coin was still fixed in position by the dies.  Collar shimmy is known among 1976 Argentina 50 centavos coins and one domestic coin.

This 1996-P quarter dollar represents the only known case of collar shimmy among domestic coins.

The planchet was slightly uncentered and was forced down into a collar that was frozen in a partially deployed position.  This created a stiff collar error (with a strongly cupped unstruck crescent) and a partial collar error.  After the hammer die reached the lowest point of its downstroke, the collar sprang up (probably in a tilted position) and was driven deeply into the coin’s edge between 6:00 and 9:30.  The collar then twisted back and forth, pushing some reeds to the side and other reeds together.

Other errors that appear on this coin include a horizontal misalignment of the hammer (obverse) die toward 6:30 and a die attrition error that extends from 9:30 to 12:30.  Stiff collar errors, die attrition errors, and horizontal die misalignments all result in collar impacts.  Such impacts could have destabilized the collar, facilitating the collar shimmy error.

Part VI. Striking Errors:

“Struck-through” errors:

Struck through die fill:

Grease strikes:

Grease-mediated radial smear

Definition: Radial smearing of the design caused by “grease” (die fill).  The edges of the design that face toward the center of the coin are smeared toward the rim.  Radial smearing can affect both interior and peripheral design elements.  Although the mechanism is conjectural, the effect is likely caused by the interplay between viscosity, die convexity, and planchet expansion.  It’s possible that as the die is pushing its way into the planchet it is also squeezing the grease outward.  As the grease makes contact with metal that’s rising into the die’s recesses, it smears the metal outward in a radial fashion.

In rare cases, the direction of smear can be toward the center of the coin, or in both directions simultaneously.

Grease-mediated radial smear is similar in appearance to the metal flow that affects broadstrikes and off-center strikes and to a form of machine doubling called slide doubling.  Although all produce a smearing effect, they are unrelated.

This 1989-P dime shows radial smearing of the peripheral design elements.  The effect is best seen on LIBERTY.  Note that the direction of smear is identical to the radial flow lines that developed in the field portion of the die as the result of die wear.

In this specimen, grease-mediated radial smear has affected the date and, to a lesser extent, LIBERTY.  A close-up of the date shows the direction of smear.  Once again, radial die flow lines follow the direction of smear.

Patterns and Prototypes (accidental release)

Definition: A lumpy texture that develops on the unstruck portion of certain broadstrikes and off-center strikes.  Known exclusively among 1993-P nickels, the lumpy texture forms during the strike in response to compressive and tensile stresses.  The texture may reflect uneven patterns of crystallization (or crystallite merger) occurring within the underlying metal.  However, the actual etiology is obscure.

This massively expanded, broadstruck 1993-P nickel displays stress-induced surface irregularities on the unstruck perimeter and along the edge.

Stress-induced surface irregularities appear on both sides of the unstruck portion of this off-center 1993-P nickel.  The lumpiness is strongest near the upset edge and next to the internal margin of the die-struck tongue of metal.  Compressive stresses generated during the strike produced a lumpy texture along the outer edge of the struck tongue.