PART VI. Striking Errors:
Multiple strikes:
In-collar/out–of-collar
Definition: Multiple strikes can occur inside the collar or outside the collar.
A 1998 Lincoln cent double struck in-collar with 90 degree rotation between strikes.
Definition: Multiple strikes can occur inside the collar or outside the collar.
A 1998 Lincoln cent double struck in-collar with 90 degree rotation between strikes.
Definition: Collar clash on the reverse die, with the reverse die acting as the anvil die.
Collar clash is virtually unknown on reverse dies installed in the traditional fashion, i.e., with the reverse die acting as the anvil die. Anvil die collar clash can develop if the neck of the die is shoved violently into the ridged working face of the collar or vice versa. Anvil die collar clash can also develop if the neck of the collar grinds up and down against the collar (or vice versa).
This undated, off-center dime shows anvil die collar clash on its reverse face. Because the coin was struck out-of-collar, the familiar serrations of collar clash have been transformed into a series of transverse grooves located within the coin’s slide zone. This dime also displays three indentations in its edge, which represent pre-strike planchet damage.
Definition: A collar that has undergone plastic deformation. This could leave it wider than normal (a subtype of wide collar error). It could leave the collar with a sloping working face instead of a vertical working face. Reeding (if present) might be obliquely oriented instead of vertical.
A group of 1982 500 Lira coins struck by the same dies and within the same collar display a deformed collar that also rotated between strikes. A large collar chip located on the edge of the coin occupies a different position relative to the design in three representative specimens.
Although struck fully within the collar, the edge of the coin is beveled, reflecting the fact that the working face of the collar had a sloping cross-sectional profile. The intermittent reeding, which should be vertically oriented, is instead obliquely oriented.
Deformation of the collar also produced a coin that is slightly out-of-round and wider than normal. Width is about 0.8 millimeters greater than normal, while the coin’s north-south diameter is 0.5 millimeters greater than the east-west diameter.
Collar deformation this severe is rarely encountered because the collar is ordinarily harder than the dies. A collar is much more likely to break than deform. This collar did both.
Images courtesy of Cosimo Manisi, with the assistance of Andrea Del Pup.
Description: A second strike in which minimum die clearance has increased to such an extent that the dies only touch down on the design rim. Second strikes of this nature must also be off-center strikes.
Rim-restricted second strikes can be confused with similar-looking but unrelated striking errors. If it’s only slightly off-center, a rim-restricted second strike will look very much like a case of rim-restricted design duplication. The latter is a form of machine doubling in which the hammer die (it’s nearly always the hammer die) bounces off the surface of the coin, shifts to one side, and lands lightly on the design rim. If the second strike is significantly off-center, then a rim-restricted second strike can be confused with a double strike in which the first strike is off-center and minimally expanded while the second strike is centered.
This 2005 cent received a normal first strike and a slightly off-center rim-restricted second strike. Unlike a case of rim-restricted design duplication, die-struck design elements are present on both faces.
This 1992-P quarter received an abnormally strong first strike that caused finning of the design rim on the left side. The second strike is about 75% off-center, rotated 90 degrees clockwise, and die-struck on both faces. Second-strike design elements are almost completely restricted to the design rim. On the reverse face, the only recognizable second-strike feature is the design rim. No interior design elements are present on the reverse because much of the resistance to the impact of the hammer die was provided by a slightly elevated collar. This simultaneously softened the impact of the anvil die so that no details managed to strike up. DR2 = 2nd Strike Design Rim
Definition: A brockage is an incuse, mirror-image design generated when a coin is struck into a planchet.
NOTE: Brockages can be in-collar, out-of-collar, centered, or off-center. They can be aligned with, or rotated relative to, the opposite, die-struck face. The degree of expansion and distortion depends on how many previous planchets were struck and whether one or both participants in the error were confined by the collar.
A Lincoln memorial cent with an in-collar, first-strike brockage of the reverse design on the obverse face. A cent that had stuck to the obverse (hammer) die was struck into the next planchet that was fed into the striking chamber beneath it.
|
Definition: A stutter strike occurs when the hammer die makes transient contact with a planchet without there being any resistance provided by the anvil die. Resistance is provided by other means. After the initial light contact, the hammer die completes its downstroke in a position medial to the site of original contact. The stutter strike is restricted to a thin outlying crescent that is sharply demarcated from the adjacent complete design. Directly opposite the stutter strike, on the face struck by the anvil die, the original surface of the planchet persists unaltered.
In a Type I stutter strike resistance is provided at one pole by a stiff but still somewhat mobile collar. It’s surmised that the die, die assembly, or collar has to be loose as well because stiff collar errors are common but stutter strikes are not. After the collar gives way, the hammer die completes its descent in a position slightly medial to the original point of contact. The thin outlying crescent will be abruptly demarcated from the adjacent complete design. The die-struck crescent will, at best, contain the tips of peripheral letters.
This 1998-P quarter shows a Type I stutter strike on its reverse face. The coin was struck by inverted dies, meaning that the reverse die was the hammer die. The planchet was fed into the striking chamber in a slightly off-center position, with the southern pole of the obverse face resting on the lip of the collar or against its beveled entrance. The collar resisted being depressed for a split second, allowing some die-struck letters to form at the periphery of the planchet. This also produced a weak, sloping shoulder on the obverse face. The collar then collapsed, allowing the hammer die to complete its downstroke without further warping the planchet. The coin shows a partial collar error next to the stutter strike.
Definition: A stutter strike is a rare error that can be thought of as the polar opposite of machine doubling. While the extra impressions of machine doubling occur after the downstroke of the hammer die reaches its lowest point, a stutter strike occurs before the downstroke has completed its downward trajectory. In a stutter strike, the hammer die makes initial light contact with the surface of the coin, but completes its descent in a slightly different position relative to the original point of contact. The result is a thin crescent of design at the outer margin of coin, distinctly separate from the definitive strike.
A stutter strike can result from movement of the die, movement of the coin, or expansion of the coin during the downstroke. It always occurs together with at least one other press malfunction or error. Associated errors include an off-center strike or broadstrike atop a stiff collar, an indent or partial brockage, or a loose die in combination with any of the aforementioned errors.
The Indian 1998 5 rupees below features a double row of denticles opposite a large indent on the reverse face. As with most Indian coins, the reverse face was struck by the hammer die. While the double row of denticles may appear to be a double-strike, closer inspection shows that it is, instead, a stutter strike.
In the case of this 5 rupees coin, the factors underlying the production of a double row of denticles appears to be the indent, in combination with a loose hammer die or die carriage. The presence of an intrusive planchet caused uneven pressure to be applied to the planchet represented by this coin. The area overlain by the intrusive planchet received the initial force of the strike, which tipped up the part of the planchet lying beyond the indent. The elevated outer portion of the planchet contacted the perimeter of the descending hammer die so that the former picked up an initial row of denticles. Simultaneous with that contact, the hammer die shifted medially and completed its downstroke, producing the second row of denticles along with the main strike. The main strike is misaligned relative to the obverse design, which was struck by the anvil die.
The stutter strike shown below is associated with an indent on the left side of the obverse face. The intrusive planchet was contacted first by the descending hammer die. This caused the right side of the underlying planchet to angle up and meet the hammer die on its way down. That light initial contact left a weakly-struck crescent on the right side of the coin that contains the TY of LIBERTY and the date. As the hammer die continued its descent, it compressed both planchets. This caused both planchets to expand in all directions. The expansion of the underlying planchet carried the lightly-struck crescent on the right side beyond the edge of the striking chamber. The hammer die then completed its descent, producing the definitive design.
The stutter strike lies lateral to the definitive design on both the obverse and reverse face. It is opposed on the reverse face by the original unstruck surface of the planchet.
Definition: A stutter strike occurs when the hammer die makes transient contact with a planchet without there being any resistance provided by the hammer die. Resistance is provided by other means. After the initial light contact, the hammer die completes its downstroke in a position medial to the site of original contact. The stutter strike is restricted to a thin outlying crescent that is sharply demarcated from the adjacent complete design. Directly opposite the stutter strike, on the face struck by the anvil die, the original surface of the planchet is persists unaltered.
There are three types of stutter strikes which are not closely related to each other except with respect to the final outcome:
Type I. Here the resistance is provided at one pole by a stiff but still somewhat mobile collar. It’s surmised that the die or die assembly has to be loose as well because stiff collar errors are common but stutter strikes are not.
Type II. In this form of stutter strike, one pole of a planchet is tipped up into the path of the descending hammer die by an intrusive object at the opposite pole (typically a coin or a planchet). The upwardly-tilted portion of the planchet makes brief contact with the hammer die before it is pushed laterally beyond the boundaries of the striking chamber by the prematurely expanding metal at the opposite pole. The hammer die completes its descent in a position medial to the point of initial contact.
Definition: This error occurs when a coin is struck at least twice and the subsequently strikes shows an offset in direction.
A horizontal, vertical, pivoted, or rotational misalignment can occur on the second strike after a normal first strike. It’s also possible for a misaligned die strike to precede a normal second strike, although this has only indirectly been documented through clash marks.
In this 1999 cent, the hammer (obverse) die was centered during the first strike. Between the first and second strike, it shifted to the right about 10%. Before the hammer die descended a second time, an unstruck planchet intruded into the striking chamber, leaving an indent on the left side. Details of the first strike can be seen in the floor of the indent. The second strike also shows a partial collar error
Edge lettering applied after strike (incuse) (small dollar coins)
Note: Edge lettering and other edge design elements may be impressed during upsetting, during the strike, by a special machine before the strike, or by a lettering device after the strike. Similar-looking defects can occur in each of these processes. Any edge design that forms a closed interlock between the edge of the coin and the collar cannot be produced during the strike since that will prevent ejection of the coin after the strike.
Special Note: Some presidential dollar coins have had the edge lettering removed outside the mint. Use caution when buying any edge lettering error.
The diagnostics for authentic presidential coin missing its edge lettering are as follows:
1. Diameter should be 26.46 mm. Coins altered outside the mint will have a diameter that is less than 26.46 mm and will have a diameter of approximately 26.21 mm.
2. The coin’s weight should be approximately 7.98 g ± .03 g. Altered coins will weigh less from the removal of the edge lettering. Weights of approximately 7.89 g are commonly seen on altered coins.
3. An unaltered presidential dollar coin will have vertical lines along the edge. These lines are created when the coin is ejected. Altered coins will not normally have these lines, but instead will have horizontal lines. These horizontal lines are from milling or similar machines used outside the mint to remove the letters and are the aftereffects of the metal being abraded off the coin.
The above image shows the vertical lines present on the edge of an unaltered presidential dollar coin with no edge lettering
Table of edge lettering errors found on the presidential and native American dollar coins
Post-strike chemical treatment
Matte or frosted finish applied after strike