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Wide Collar

Part IV. Die Errors:

Collar Manufacturing Errors:

Wide Collar

Definition:  A coin struck inside a collar whose diameter is wider than normal.  This rare error is subtle and is often only detected when an otherwise normal-looking coin gets stuck in a plastic storage tube or won’t fit in its designated hole inside a cardboard Dansco album.

An abnormally wide collar can arise in several ways:

1. A collar intended for a different (perhaps foreign) denomination is inadvertently installed in a press.
2. A smooth-faced collar is mistakenly machined too wide.
3. A reeded collar is widened beyond normal tolerances through the use of an incorrect ridged broach that is
hammered into the collar opening.
4. A normal collar is not replaced in a timely manner and widens due to prolonged use.
5. The presence of three or more vertical collar cracks allows the collar to expand.The last two circumstances are probably the most common causes of this error.


This 1918 cent was struck in a collar that expanded due to the presence of four vertical collar cracks.  Its diameter
measures 19.45 mm instead of the normal 19.05 mm.

The above 1999-P dime was struck in an abnormally wide collar. The diameter of this dime measures 18.24 mm instead of the normal 17.91 mm.  It’s likely that the collar expanded due to the relentless pounding involved in restraining hundreds of thousands of planchets.  The edge is slightly convex in vertical cross-section, which is consistent with this scenario.  This dime also shows a case of surface film transfer on the obverse face.  This type of error occurs when the preceding coin is double struck with movement between strikes.  If either the coin or the die is grimy, a shadow image of the first strike is transferred to the die face and then transferred back to the next planchet.

For more information on wide collar errors see the May 17, 2010 Coin World.

Deformed Collar

Part IV. Die Errors:

Deformed collar


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.

Partial Collar

PART VI. Striking Errors:

Collar Deployment Errors:

Partial collar


Definition: A coin struck within a partially deployed collar.      

A partial collar error is one in which the planchet is only partially confined by the collar. The lower half of the edge shows contact with the working face of the collar while the upper half of the edge is smooth, beveled, or both.

A collar can occupy a partially deployed condition for two reasons:
1. It might have been depressed part of the way toward the anvil die face by the pressure applied by a tight-fitting or poorly centered planchet (backed, of course by the hammer die).
2. It might never have occupied a fully elevated position. Its deployment may have been blocked by a poorly centered coin (in presses where the anvil die is fixed and the collar moves up and down). Its deployment might have been interrupted for other reasons, such as debris getting trapped between the collar and the anvil die neck.

A partial collar error can be level or it can be tilted. Tilt can be so great in some instances as to leave one pole fully in contact with the collar and the other completely above the collar. The transition between the collar-struck portion of the edge and the unstruck portion can be abrupt or can be separated by a beveled interval. This zone is caused by contact with the beveled entrance of the collar. The beveled entrance can be wide, narrow, or sometimes absent. The beveled entrance often shows horizontal machining marks, which are transferred to the edge of the coin. In presses with a standard or traditional setup, the collar-struck edge is next to the reverse face (struck by the anvil die). In the inverted setup, the collar-struck edge lies next to the obverse face (struck by the anvil die). The latter setup is also called a “reverse partial collar” or a “reversed partial collar”. Uneven machining along the top of the collar’s working face can generate an undulating partial collar. When a coin returns to the collar for another strike, it often has trouble fitting back into it. It may depress the collar partway, resulting in a “re-entry partial collar”.


The edge of this 2000 New Jersey quarter dollar shows a level partial collar error with a bevel above the reeding. The bevel was caused by contact with the beveled entrance of the collar. Typical horizontal machining marks appear on the beveled surface of the coin’s edge.


This 1978 quarter dollar was struck within a severely tilted collar. The left side is fully reeded while the right side is smooth. In order to show the entire edge, the photo was taken with the coin sitting in a flashlight reflector.


This 1996-D dime shows a reversed partial collar. It was struck in a press with an inverted die setup (reverse die as hammer die).


This 1994-P dime shows an undulating partial collar. The beveled entrance was machined unevenly, so that the upper margin of the collar’s working face follows a wavy path.

Collar Damage

Part IV. Die Errors:

Die Damage:

Collar damage


Definition: Mechanical damage affecting the working face of the collar. This damage can appear as scratches and grooves that are horizontally or vertically oriented.

This 1970-D nickel features a sizeable cud (corner die break) on the obverse. The section of the edge next to the cud carries coarse vertical grooves that reflect damage to the collar. It’s possible that gritty debris derived from the collar break became trapped between the neck of the anvil die and the collar. Either that, or a collision with a foreign object that was responsible for the cud also caused that foreign object to shatter, with the resulting debris getting trapped between the die neck and the collar. Vertical movements of the anvil die relative to the collar ground the debris against the collar, generating the vertical grooves. Every nickel struck afterward carries the impression of that damage. The grooves on the nickel could be partly an impression of the damage and partly due to the nickel scraping against the damaged portion of the collar during ejection.


The upper member of these two 2008-P New Mexico quarter dollars displays unusually wide, flat valleys between the reeds, with the valleys carrying heavy horizontal scratches. This appearance reflects the fact that the ridges on the working face of the collar were abraded and truncated. Similar damage is known from other dates, including 2007-P Wyoming quarters. This damage may have been produced when the beveled entrance of the collar was being machined or de-burred. The rotating machine tool may have slipped into the functional portion of the collar, damaging the reeding.

Ejection Doubling

Part VI. Striking Errors:

Ejection doubling


Definition: A form of widely offset, raised doubling that appears on the face struck by the anvil die.

The term “ejection doubling” was traditionally applied to minor smearing of the design generated by the anvil die. The idea was that the newly-struck coin resisted being pushed off the anvil die face by the ejector, causing the raised design elements to catch on the edges of the die’s recesses.

Since traditional ejection doubling is indistinguishable from minor slide doubling (a form of machine doubling), it was retired from use. Slide doubling results from lateral movement of either die at their moment of closest approximation or just as the hammer die is lifting off the surface of the coin.

In 2022, ejection doubling was resurrected and applied to widely offset raised doubling that is not smeared and that appears on the face struck by the anvil die. The distance between primary and secondary design elements is too great to represent push doubling (another form of machine doubling) because the amount of play available between anvil die and collar is insufficient.

James Hitchcock discovered the 2008-P 5-cent “type specimen” that has been used to define this new form of doubling to which the old moniker “ejection doubling” has been applied.

The doubling appears on the obverse face, which was struck by the anvil die. A secondary, right-positioned eye is located 0.5 millimeters below the normal eye. The primary eye also shows close doubling that would have been classified as push doubling had the more distant eye not been present.

The gap between the primary eye and the distant secondary eye is too great to be explained by the recoil and lateral shift of the anvil die within a fixed collar. There are at least two possible explanations:

  1. It’s possible that, once the coin was pushed up out of the collar, both the anvil die and the collar shifted southward at the same time that the anvil die was recoiling from, and returning to, the coin’s reverse face. Delayed retraction of the hammer die may have been necessary to maintain resistance to the impact of the anvil die.
  2. The newly-struck coin adhered to the hammer die face and was carried along as the hammer die bounced upward, shifted laterally, and sank downward again. This allowed the lower face of the coin to make light, secondary contact with the anvil die. This scenario requires the coin to be free of the collar’s embrace but does not require movement of the anvil die or collar.

MD-12

Machine parts above collar can impede expanding

coins

By Mike Diamond | May 21, 2011 10:00 a.m.
Article first published in 2011-05-30, Expert Advice section of Coin World

51863654

 

An off-center cent with a “sideneck strike.” Driven toward the northeast by the expanding die-struck portion of the coin, the unstruck edge collided with the side of the adjacent hammer die neck.

Images by Mike Diamond.

As a coin is struck, its expansion is abruptly halted by the surrounding collar.

When the collar fails to deploy, a coin expands in all directions. As a result, all off-center strikes and broadstrikes are wider than a normal coin, to varying degrees.

On some occasions a coin’s expansion is impeded, and the edge damaged, by machine parts positioned above the collar plate.

The most familiar obstacle to unfettered expansion is the neck of an adjacent hammer die. In a dual or quad Bliss press (the last of which was retired in 2005), the close proximity of adjacent die pairs results in the occasional production of a “sideneck strike,” also referred to as an “almost saddle strike” or a “one-die saddle strike.”

A typical example is shown here in an off-center Lincoln cent. At the pole opposite the 1 o’clock position of the obverse face, we see a deep, concave notch and an associated pressure ridge. The planchet represented by this coin lay partly within one striking chamber and almost managed to encroach on the adjacent striking chamber. In other words, the coin fell just short of becoming a “saddle strike.” When struck, the expanding die-struck area pushed the unstruck portion toward the adjacent striking chamber. It collided with the side of the hammer (obverse) die neck as the latter was striking its own coin.

Sideneck strikes are always concave and always closest to the adjacent striking chamber. In most years, this chamber would lie along a line drawn from the 1 o’clock position in Lincoln cents, or the 11 o’clock position in Jefferson 5-cent coins and Roosevelt dimes.

Strike-related edge damage of another kind is seen in an undated Jefferson 5-cent coin. The pole opposite the off-center strike has a flat, vertically oriented contact facet. It appears that the facet was produced when the unstruck portion of the planchet was pushed south by the expanding die-struck area and collided with a machine part. Another possibility is that the coin was hit while momentarily immobilized by the two dies.

In either case, we can’t be sure what machine part was responsible, although I suspect a feeder finger. I’ve encountered these flat facets on quite a few off-center and double-struck cents and 5-cent coins. In each case, the strike is about 70 percent off-center and the contact facet lies opposite the base of the bust.

The introduction of the Schuler press introduced new types of strike-related edge damage. This press uses a single die pair, with the reverse die operating as the hammer die. The damage is primarily associated with multi-struck coins. A representative example is provided by a quadruple-struck 5-cent coin. The first strike was normal. The other strikes were delivered about 20 percent off-center and are closely spaced. Edge damage is present on both the right and left sides. The contact facet on the right side is convex, slightly beveled, and extends from 12 o’clock to 2:30.

The dies evidently struck whatever machine part rested against the coin. On the left side the coin buckled when it collided with a hard object. The contact facet here is quite compact and lies next to the w of we. It’s possible that the coin was pushed laterally into an obstruction by expansion produced by the off-center strikes. It’s also possible that an object hit the coin as the latter was temporarily immobilized between the dies.

This type of edge damage can be found on numerous multi-struck cents, 5-cent coins, and Washington quarter dollars struck by Schuler presses. The pattern is consistent, although the long facet and the short facet can be located on either the right or the left side.

The affected coins all show a sequence of strikes involving a normal (or at least centered) first strike, and one or more closely spaced off-center strikes. Coins in which the off-center strikes are widely spaced or erratically positioned typically do not show this edge damage. The long facet that hugs the edge of the off-center strikes is almost certainly caused by contact with a feeder finger. I’m not sure about the short facet.

Coin World’s Collectors’ Clearinghouse department does not accept coins or other items for examination without prior permission from News Editor William T. Gibbs. Materials sent to Clearinghouse without prior permission will be returned unexamined. Please address all Clearinghouse inquiries to cweditor@coinworld.com or to (800) 673-8311, Ext. 172

http://www.coinworld.com/articles/machine-parts-above-collar-can-impede-expandi/

Copyright 2012 by Amos Hobby Publishing Inc. Reposted by permission from the March 22, 2012, issue of Coin World.)

 

Part IV. Die Errors:


Reeding vs. no reeding varieties (foreign only)

Concentric lathe lines (ES Nov/Dec 2003)

    • Various years and denominations
      • Common on the 1996-D Lincoln cent

Rusted dies (CW 12/1/08)

Excessively deep rim gutter

    • 1991 cents

Rockwell test mark left in die (hemispherical bump seen on coin) (ES July/Aug 2006)

Vickers test mark left in die (pyramidal bump) (CW 5/15/17)

Collar manufacturing errors

    • Wide collar (ES Nov/Dec 2002; CW 5/17/10)
      • Created by improper machining or improperly machined broach
      • Created by use of wrong broach
      • Improper use of correct broach
      • Widening due to wear
      • Widening due to 3 or more vertical collar cracks and associated expansion (CW 5/17/10)
    • Abnormal reeding
      • 1921 Morgan dollar with infrequent reeding
      • 1924-D Mercury dime with infrequent reeding
      • 2015 American Eagle 1/10oz gold bullion coin with narrow reeds (CW 7/13/15)
      • Low, narrow reeds caused by truncation of ridges on collar face (ES March/April 2010; CW 1/25/10, 4/16/12)
        • 1964-D 25c
        • 2008-P New Mexico 25c
          • COIN WORLD SPECIAL: article posted HERE

Hub retouching

Die retouching (CW 5/30/16, 9/30/19)

Die damage (ES Nov/Dec 2004, Jan/Feb 2003; CW 5/21/12)

    • Die dents (ES Nov/Dec 2004, July/August 2005, Nov/Dec 2005; CW 9/15/03, 12/22/14, 3/28/22, 7/31/23)
    • Die scrapes (CW 4/23/07)
    • Accidental die scratches
    • Die gouges
    • Impact scars
    • Accidental die abrasion (CW 9/8/14, 12/16/19)
    • Intentional die abrasion (“die polishing”) (CW 3/29/10, 5/31/10, 9/8/14, 3/20/23)
    • Defects related to die polishing
      • Over-polished proof and Special Mint Set dies (CW 2/21/11)
      • Trails and Wavy Steps (ES July/Aug 2006, Sept/Oct 2006, Nov/Dec 2006, Jan/Feb 2011; CW 3/8/10)
      • Localized removal of field from proof polishing (CW 2/14/2011)
        • COIN WORLD SPECIAL: article posted HERE
    • Die attrition errors (ES May/June 2003, March/April 2005, March/April 2009; CW 1/4/10, 12/24/12, 4/14/14, 11/4/19, 7/3/23, 10/16/23)
    • Other forms of peripheral die damage (ES March/April 2005; CW 8/9/21, 3/14/22)
    • Catastrophic die damage (ES March/April 2002; CW 9/15/03, 9/12/11, 9/19/11, 5/20/13, 10/27/14, 6/19/17)
    • Cancelled or defaced dies (foreign only) (CW 5/8/17, 12/31/18)
      • 1994 Hong Kong bimetallic 10 dollars
      • Egypt 25 piastres struck by defaced 50 piastres dies (CW 5/12/14)
      • 1966 Bolivia 10 centavos struck by pair of canceled dies (CW 5/8/17)
      • Chilean test dies with concentric cancellation pattern struck over struck foreign core (CW 5/8/17)
    • Rockwell test mark in die (CW 5/15/17)
    • Vickers test mark in die (CW 5/15/17)
    • Die rings (tiny rings, semicircles, crescents, and spirals)  (CW 2/20/17, 1/18/21, 6/13/22)
        • Centrally-located
        • Offset
  • Collar damage (ES March/April 2010; CW 1/25/10, 4/16/12, 6/17/19)
    • Horizontal abrasion (CW 1/25/10, 4/16/12)
    • Vertical abrasion (CW 6/17/19)

Hubbed-In debris (CW 5/27/13)

Deformed collar (CW 12/18/20)

Clashed dies (ES March/April 2002; CW 3/22/10, 4/30/12)

  • Floating die clash (collision with die fragments) (ES May/June 2002, May/June 2005; CW 7/19/10)
  • Superclash (full reciprocal design transfer) (CW 3/22/10, 10/22/18)
  • Circumferential clash marks (CW 12/10/18)
  • Grease-enhanced clash marks (CW 10/16/17)
  • Associated with weak strikes (CW 12/2/19)
  • Clashed die progressions (CW 5/15/23)

Collar clash (CW 6/11/07, 2/24/22)

Die damage with design transfer

    • Floating die clash (ES May/June 2002, May/June 2005; CW 7/19/10)
    • Floating (Type 2) counterclash (ES May/June 2002, July/August 2002, Sept/Oct 2002, Jan/Feb 2009, Sept/Oct 2011; CW 9/29/08, 12/13/10, 4/9/12, 4/21/14, 6/8/15, 4/23/18, 2/21/22, 12/19/22, 2/20/23)
      • COIN WORLD SPECIAL: article posted HERE
    • Miscellaneous and unexplained forms of design transfer/duplication
      • Some presumed Canadian counterclashes may prove to be something else

Die deterioration/deformation errors

Die breaks

Die exfoliation errors (CW 10/19/20)

Collar breaks (collar cuds) (ES May/June 2008; CW 11/22/10, 5/17/10, 11/22/10, 12/19/16)

Die cracks (CW 4/25/16)

Split dies (ES Jan/Feb 2006; CW 6/2/03, 4/10/06, 4/17/06, 6/20/2011, 5/11/15, 9/17/18, 4/26/21, 4/18/22, 7/18/22)


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet

Part III. Die Installation Errors:


Mules (ES May/June 2010)

    • Wrong hammer die
      • 2005 Malaysian 1 sen obverse die paired with 10 sen reverse die and struck on a copper-nickel 10 sen planchet in a 10 sen collar
      • 1995 cent/dime mule
    • Wrong anvil die
      • Malaysian 1 sen reverse die paired with a 2005 10 sen obverse die and struck on a copper-nickel 10 sen planchet in a 10 sen collar
      • 1993-D and 1999 cent/dime mules
    • Wrong hammer and anvil die
      • 2005 Malaysian 1 sen obverse and reverse dies used to strike a 10 sen planchet in a 10 sen collar
      • Maryland quarter on Sac planchet in Sac collar (3 specimens)
    • Two anvil dies
      • Foreign
        • 1982 Jamaica cent with two obverse faces
        • Chilean 100 pesos bi-metallic with two obverse faces (1 known specimen)
        • 1 Euro cent with two reverse faces
      • Domestic
        • Two-tailed clad dime (1 known specimen, probably from 1965)
        • Two-tailed clad quarter (3-4 known specimens, probably from 1965)
    • Two hammer dies
      • Foreign
        • 1982 Jamaica cent with two reverse faces
      • Domestic
        • 1859 Indian cent with two obverse faces (unique)
        • 1863 Broas Pie Bakers token (Civil War Store card token)
    • Two obverse or two reverse dies (die setup unclear)
      • 2000-P nickel with two obverse dies (CW 6/26/17)
    • Two different countries
      • (1967) Bahamas 5c/New Zealand 2c mule
    • Different denominations
      • Washington 25c/Sacagawea $1 mules (16 specimens, 3 die pairs)
        • COIN WORLD SPECIAL: article posted HERE
    • Mule die larger than normal die and collar
      • 1995 cent/dime mule
    • Mule die same size or smaller than normal dies and collar
      • (All known U.S. mules employ dies of different sizes)
    • Temporal mule (mule die representing same denomination but from an earlier or subsequent year) (CW 1/24/14)
    • Temporal/transitional mule (dies from different years with change in planchet composition) (CW 5/9/16)
    • Regular-issue die muled with commemorative die
    • Regular-issue die muled with government medal or token die
    • Regular-issue die muled with private token, medal, or nonsense die (ES Jan/Feb 2008, CW 11/25/13)
    • Mules involving pattern dies (various types)
      • Normal die paired with pattern or prototype die (CW 2/2/04)
    • Collar mules (collar from different denomination of same or similar size installed)
    • Lettering die mule (mismatch between edge lettering applied before or after strike and the design shown on the obverse and reverse face)
      • Presidential dollar with wrong date on edge.
        • 2009 Zachary Taylor dollar with 2010-D edge inscription (rather than 2009-D inscription) (CW 2/22/10, 3/1/10)
      • 2007-D Sacagawea dollar with Presidential dollar edge lettering (CW 7/9/12)
    • Pseudo-mules (3 pathways) (CW 4/25/11, 3/19/12, 4/23/12, 12/11/17, 12/17/18, 2/22/21, 12/12/22) COIN WORLD SPECIAL: article posted HERE
      • Canadian Pseudo-mules
        • COIN WORLD SPECIALS: articles posted HERE and HERE
      • One U.S. two-tailed quarter may belong in this group (CW 11/27/04, 8/27/12)

Mismatched business / proof dies

Finished proof die matched with business die

    • Early 19th century examples (CW 8/20/12)

Transitional Reverse (Minor temporal mismatches) e.g.:

Inverted die installation (not an error) (CW 2/15/10, 7/22/19, 1/6/20)

    • Older issues struck with inverted dies (e.g. buffalo nickels and Mercury dimes)
    • Re-introduction of inverted dies (beginning 1989) (CW 12/11/23)
    • Saddle strikes produced by inverted dies (CW 9/13/10, 9/19/16)

Late use of traditional die setup (CW 6/5/18)

Fixed rotated die errors (see Part VI)

Collar Installation Errors

    • Smooth edge instead of reeded edge (and vice versa)
      • 1863 Indian cent with reeded edge (CW 6/3/02)
    • Smooth edge instead of edge design (and vice versa)
    • Reeded edge instead of edge design (and vice versa)
    • Segmented proof collar with segments out-of-order (CW 4/7/08
      • 2007-S Proof Presidential dollar with segments arranged in wrong sequence (CW 4/7/08)

Use of flat, featureless dies (CW 6/30/14)

Use of cancelled and defaced dies (CW 5/12/14)

Cancellation overstrikes (coins overstruck by canceled coin, pattern or test dies) (CW 5/8/17, 5/24/21)

Design/composition mismatches (CW 2/10/20)


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet

Part V. Planchet Errors:


Alloy errors

Subsurface Corrosion (CW 12/21/15)

    • Plated coins
      • Copper-plated zinc cents
    • Solid coins

Rolling Mill Errors

Blanking and Cutting Errors

Upset Mill Errors

    • Coins struck on blank (“Type I planchet”)
    • Abnormally weak upset (ES July/August 2005)
    • Abnormally strong upset (best seen on off-center strikes)
    • “Groovy edge” (possibly from worn groove in upset mill)
    • Variation in cross-sectional shape of rim/edge junction of planchet
    • Struck coin sent back through upset mill
    • Abnormal upset (ES Sept/Oct 2005; CW 2/27/12, 11/21/16)
      • Wide, flat edge
      • Smoothly convex edge
      • Abnormally wide proto-rim
    • Squeezed-in debris (upset mill inclusion) (ES May/June 2006; CW 9/6/10)
      • Foil-like metal wraps around edge onto one or both faces
        • e.g. Copper foil on nickels (not from improper annealing)
      • Metal wire wraps around edge onto one or both faces
      • Pellet embedded in edge (CW 9/6/10, 9/22/14)

Edge design errors (impressed into planchet before strike) (includes security edge errors) (CW 6/27/16)

    • Edge design missing
    • Edge design present on normally plain edge (CW 6/27/16)
    • Wrong edge design
    • Edge design too high or too low
    • Interrupted edge design
    • Tilted edge design
    • Broken edging die (CW 6/27/16)

Mispunched center holes (foreign only) (CW 1/7/19)

    • Misaligned holes
    • Double punched center holes
      • One hole centered
      • Both holes misaligned
      • Overlapping holes
      • Totally separate holes
    • Irregular center holes
    • Abnormally small hole
    • Partial hole (from broken hole punch)
    • Circular Indentation (partial penetration)
      • Due to broken-off punch tip
    • Unpunched center hole
    • Hole punched in planchet meant for a solid coin

Annealing Errors

    • Improper annealing (due to excessive heat, prolonged exposure to intense heat, or excessive oxygen in annealing oven) (replaces “sintered plating” and “copper wash”) (ES July/Aug 2010; CW 11/30/09, 2/8/10)
      • Black, brown, red, coppery discoloration (includes “black beauty” nickels)
      • Layer of copper, often peeling

Poorly annealed or unannealed planchets (hard, brittle planchets) (CW 3/14/11)

    • Broken planchets and coins (CW 3/14/11, 9/18/23)
    • Radial cracks in coin (usually struck out-of-collar)

Brittle coins (cross-classified with alloy errors) (CW 3/14/11)

Abnormally hard planchets (CW 12/17/12, 8/15/22)

On undersized or underweight planchets (CW 2/13/12)

Miscellaneous forms of mint discoloration

Plating Errors

Bonding/Bonding Mill Errors (ES, Sept/Oct 2002)

Irregular planchets

Pristine Planchets (i.e. lacking tumbling marks) (CW 1/11/16)

Pre-Strike Damage (CW 11/15/10, 11/15/10, 1/23/12, 1/30/12, 12/15/14, 4/13/15, 6/8/20)

    • COIN WORLD SPECIALS: articles posted HERE and HERE
    • Assay clips (cross-classified with blanking errors)
    • Rim burrs (CW 1/31/11)
    • Accidentally and intentionally “re-sized” planchets (CW 9/15/10)
    • “Crimp marks” (mostly found on off-metal errors, e.g., 5c/1c, 5c/10c)
    • Rockwell test mark in planchet (circular or oval dimple) (ES July/Aug 2006; CW 10/15/18)
    • Planchet with adjustment marks (gold and silver planchets filed to return heavy planchets to normal weight)
    • Edge rolled, squeezed, and folded-over (or with thin apron produced) (CW 11/15/10, 1/23/12, 6/15/20)
    • Pre-plating damage (zinc cents) (CW 1/23/12)
    • Post-plating damage (zinc cents) (CW 11/15/10)
    • Scraped-in debris (CW 2/23/15)
    • Repetitive pre-strike damage (CW 12/15/14)
    • Other forms of pre-strike damage
      • Gouged (CW 1/14/19)
      • Crushed (CW 4/13/15)
      • Scraped (CW 2/23/15)
      • Torn
      • Crumpled (CW 8/15/11)

Inter-strike Damage (CW 1/9/12, 8/20/12)

    • Cancelled or defaced between strikes (CW 3/25/13)

Trans-strike damage (CW 7/12/21)

Wrong planchet and off-metal errors

Bi-metallic errors (foreign only) (ES Nov/Dec 2005)

    • Misaligned core (ES May/June 2007; CW 3/6/23)
    • Misaligned center hole (ES Sept/Oct 2007)
      • Well-seated core (CW 3/6/23)
      • With misaligned core (CW 3/6/23)
    • Double-punched center hole
    • Unpunched center hole
      • Solid disc of ring metal (CW 3/26/18)
      • Solid disc of ring metal with embedded core
      • Solid disc of ring metal with core indent
    • Ring with incomplete punch (ES Sep/Oct 2007)
    • Core with incomplete punch
    • Struck outer ring (ES Jan/Feb 2007)
    • Struck core (ES Nov/Dec 2006)
      • From another denomination
      • From another country (ES Sep/Oct 2009, Nov/Dec 2011)
      • Struck by solid-denomination dies
    • Wrong core inserted (ES Sep/Oct 2013; CW 10/17/22)
      • Core-sized scrap disc of ring material inserted into disc
    • Wrong ring (ES March/April 2007; CW 10/10/22)
    • Ring accidentally punched from solid planchet
    • Ring accidentally punched from solid coin (ES Nov/Dec 2008)
    • Struck ring from another country (restruck)
    • Struck core from another country (restruck)
    • Unstruck core inserted into struck ring and then restruck
    • Abnormally small core (controversial)
    • Abnormally wide center hole (controversial)
    • Abnormally thin core
    • Abnormally thick core
    • Abnormally thin ring
    • Abnormally thick ring
    • Incomplete trilaminar core
      • Missing one layer (ES Mar/Apr 2010)
      • Missing two layers
    • Core punched out of ring strip
    • Ring punched out of core strip
    • Bi-metallic planchet struck by solid-denomination dies
    • Solid-denomination planchet struck by bi-metallic dies (ES Mar/Apr 2014)
    • Bi-metallic planchet struck by wrong bi-metallic design


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet

Part VI. Striking Errors:


Unstruck blank (“Type I”)

Unstruck planchet (“Type II”)

Die alignment errors

    • Rotated die errors (CW 6/21/10, 7/9/12)
      • Rotated die due to improper installation (fixed rotation)
      • Rotated die due to improper die preparation (fixed rotation)
        • (e.g., grinding flats in wrong spot)
      • Rotated die due to movement after installation (dynamic rotation)
      • Semi-stable rotated die errors (various causes)
        • Characterized by a limited range of motion, a limited number of positions, or the presence of a single dominant position (CW 7/9/12, 8/7/23)
    • Pivoted die errors (probably involves entire die assembly) (CW 6/22/15)
    • Horizontal misalignment (CW 10/27/03, 7/25/16)
      • Hammer die (CW 2/1/10, 6/25/12)
      • Anvil die (ES Sept/Oct 2004, March/April 2005; CW 9/27/10, 1/19/15, 1/4/21, 7/19/21)
        • With misaligned collar
        • With broken collar
      • Dynamic misalignment (CW 6/25/12)
      • Multiple misaligned strikes (CW 10/11/21, 11/29/21)
      • Stable misalignment
      • On double-struck coins
        • On first strike only (CW 8/31/20)
        • On second strike only (CW 5/19/08, 5/23/11, 9/9/13)
        • On both strikes
        • Alignment with off-center strikes (CW 8/19/19, 8/26/19)
    • Vertical misalignment (tilted die error) (ES Jan/Feb 2003, Sept/Oct 2003; CW 12/8/03, 12/20/10, 8/24/15, 10/24/16, 1/8/24)
      • Hammer die (CW 2/1/10, 6/17/13)
      • Anvil die
      • Dynamic misalignment (CW 10/24/16)
      • Stable misalignment (CW 1/29/14)
      • Associated with weak strike (? 2/1/10, 10/8/12, 8/16/21)
      • Associated with off-center strike (? 8/13/18)
    • Dual misalignments (both dies misaligned in different directions) (CW 11/28/11, 5/18/15, 1/9/17, 7/9/18)
    • Compound misalignments (CW 8/24/15)
      • Horizontal and vertical
      • Horizontal and rotated
      • Rotated and vertical
    • Forced misalignments (CW 8/28/17)

Collar alignment errors

    • Misaligned collar
      • Associated with misaligned anvil die
      • Associated with stiff collar error
      • Associated with elliptical strike clip
    • Rotating collar (detectable only when there’s a collar break and a multi-coin progression)

Collar deployment errors

    • Partial collar (CW 2/24/20)
      • Flange with bevel
      • Flange without bevel
      • Tilted partial collar
      • Undulating partial collar (CW 2/24/20, 7/25/22)
      • Re-entry partial collar
      • Incomplete ejection partial collar (CW 12/26/22)
      • Reversed partial collar (not an error)
      • Multiple steps (CW 3/15/21)
    • High deployment of collar with coin metal extruded beneath (doubtful)
    • Broadstrikes
    • Stiff collar errors (ES Nov/Dec 2000; CW 8/25/08)
      • Normal die installation
      • Inverted die installation
      • Association with misaligned dies
      • Association with misaligned collar
      • Strong collar scar
      • Strong collar scar with cupping
      • Planchet forced completely into fully deployed collar (“ram strike”) (ES Nov/Dec 2000, March/April 2001)
      • Elliptical strike clip (ES March/Apr 2000; CW 4/5/10)
      • Associated with weak strike (CW 2/11/13)
    • Collar shimmy (CW 8/21/17, 9/11/17)

Weak Strikes (ES Sept/Oct 2000; CW 5/3/04, 9/11/06, 6/18/07, 3/1/10, 5/23/11, 6/23/14, 8/27/18, 3/2/20, 10/26/20, 11/27/23)

    • Caused by insufficient die approximation
    • Caused by abnormally low ram pressure
    • Invisible strikes (ES March/April 2003, Nov/Dec 2003, March/April 2004, Nov/Dec 2006, May/June 2010; CW 5/3/10, 9/20/10)
      • With indent
      • With partial brockage
      • With struck-through error
    • Followed/preceded by strong strike (CW 7/13/20)
    • Stable series of weak strikes (CW 8/27/18)
    • Weak saddle strike
      • One strike weak, one strong (CW 4/8/13)
      • Both strikes weak (CW 12/12/11)
    • In combination with other striking errors
    • Rim-restricted first strike (CW 3/1/10, 10/10/11, 1/11/16, 2/19/18, 9/23/19)
    • Rim-restricted second strike (CW 9/21/15, 2/13/17)

Skidding Coin Errors (CW 1/29/18)

Abnormally Strong Strikes

Stutter Strikes (ES Nov/Dec 2001, Sept/Oct 2007; CW 12/28/09, 7/25/11, 8/10/20)

    • Due to spasmodically collapsing or stiff collar (Type I)
    • Due to planchet flexion (associated with indents and brockages) (Type II)
    • Due to contact with bent planchet or coin (Type III)
      • On face struck by anvil die (CW 8/26/13)

Concentric strike lines generated by a single strike (ES Jan/Feb 2012; CW 12/26/11)

Machine doubling (a.k.a. machine doubling, machine doubling damage, machine damage doubling, mechanical doubling, strike doubling, shift doubling, ejection doubling) (ES July/Aug 2006; CW 3/15/10, 7/24/17, 12/23/19, 3/30/20)

    • “Push doubling” (marginal shelving and sharp interior duplication) (CW 1/9/23)
    • “Slide doubling” (smeared design) (CW 8/14/17)
    • Rotational machine doubling (CW 8/10/15)
    • Intermediate forms
    • Multiple machine doubling in one direction (two, three, and four offset ranks)
    • Machine doubling in more than one direction (up to three directions)
    • Machine doubling on both faces of same coin (CW 3/15/10, 12/23/19)
    • Rim-restricted design duplication (see separate category)
    • Affecting incuse design elements (CW 2/6/06, 1/16/12)
    • Located on top of die break
    • Located on top of die attrition error (CW 4/14/14)
    • On out-of-collar strikes (rare) (CW 11/25/19, 11/21/22)

Rim-restricted design duplication (form of machine doubling) (CW 10/6/03, 2/22/10, 5/24/10, 12/6/10, 5/13/13, 12/30/13, 3/8/21, 4/12/21)

    • 2004 cent (ES March/April 2007; CW 2/22/10)
    • 1994 cents (CW 5/24/10, 8/22/11)
    • 1981-P quarter and 1979-D dime (CW 12/30/13)
    • Presidential dollars (ES Sept/Oct 2007; CW 2/22/10, 12/6/10)
    • Foreign coins (CW 2/22/10)
    • On face struck by anvil die (CW 10/21/13, 7/20/20)
    • Bifacial (7/20/20)
    • In conjunction with push doubling (CW 12/6/10, 7/20/20)

Ejection Doubling (CW 11/7/22)

Skidding Die Errors (CW 8/15/16, 11/27/17)

    • Skidding misalignment
      • Two-stage (CW 4/13/20)
    • Design decapitation error (top of design scraped off)
    • Slide doubling (see Machine Doubling)
    • Design ablation error (design scraped off by die movement on 2nd strike) (ES March/April 2008, Jan/Feb 2011; CW 9/13/10)
    • Combined with tilted die (CW 9/27/21)
    • From broken die (CW 7/26/21)

One-sided double-strikes (ES March/April 2000, Jan/Feb 2002, July/August 2003)

    • Hammer die rotated (CW 11/29/10)
      • Instantaneous
      • Gradual
    • Hammer die misaligned (CW 5/19/08, 5/23/11, 9/9/13, 3/8/21, 4/24/23)
      • Instantaneous
      • Gradual
    • Anvil die misaligned (CW 9/9/13)
    • Anvil die rotated (at least one known example, a proof Kennedy half dollar)
    • Rotated, with rocking die (CW 5/25/20)
    • False one-sided double strikes (CW 11/29/10)

Flat Field Doubling (imperfectly aligned proof strikes) (CW 4/29/13)

Off-center strikes

    • Cupped off-center strikes
      • With collar scar
      • Without collar scar
    • Uniface strikes
    • Stretch strikes
      • Uniface
      • Die struck on both faces (covered under high pressure strikes)
      • With unexplained, flat dent at opposite pole (not a “sideneck strike”)

Chain strikes (CW 4/12/10)

    • Normal chain strikes with straight edge
    • External chain strikes (ES Jan/Feb 2003)
    • Concave, convex, sinuous, and irregular chain strikes (ES Jan/Feb 2001, July/August 2002; CW 4/12/10)

Foreign Object Chain Strike (CW 5/25/15)

    • Chain strike against feeder

Machine Part Impingement (CW 5/25/15)

    • Bilateral
    • Unilateral

Saddle (Tandem) Strikes (CW 6/27/11)

    • Hump present
    • Hump absent
    • Inverted hump (hump points toward reverse die) (CW 9/19/16)
      • Buckling toward anvil die
      • Due to inverted die setup
    • Die position
      • Head-to-head
      • Head-to-base (early to mid- ’70s, mainly)
      • Face-to-back
    • Gap between adjacent dies
      • Narrow
      • Wide
    • With inverted die installation
    • Sideneck strikes (“one-die saddles”) (Expanding planchet collides with side of die neck) (CW 5/30/11)
    • On quarter dollars (CW 12/9/19)

Broadstrikes

  • (covered under collar deployment errors)

Split Plating Doubling

Foldover Strikes (ES July/August 2007; CW 10/10/05, 8/15/11, 1/30/12, 9/15/14)

    • Out-of-collar
    • In-collar
    • With edge strike persisting
    • On struck cents (normal and error)
    • Double foldover strikes (“Z-fold”)
    • Axial fold
    • Paraxial fold
    • Inward fold
    • Outward fold

Edge Strikes (CW 7/18/11, 10/12/15, 3/1/21)

Extrusion strikes (an effect, not an independent error) (ES March/April 2004; CW 10/24/11, 1/15/18)

Multiple strikes (CW 3/30/15)

Indents

    • In-collar/out-of-collar
    • Partial
    • Full (CW 7/30/12)
      • Centered
      • Uncentered
    • “Internal” indents (CW 11/1/10, 2/28/16)
      • On obverse
      • On reverse
    • Multiple indents
    • Irregular indents
      • Produced by error coins
      • Produced by clipped planchet
    • Indent by smaller planchet (CW 5/19/08)
    • External disc impressions (CW 3/18/19)
    • Unexpectedly shallow indents (CW 12/28/20)

Brockages

    • Full
      • Centered
      • Uncentered
      • Rotated (relative to die-struck design on opposite face)
    • Partial
      • Conventional
      • Aligned partial brockage (ES May/June 2005; CW 1/17/11, 12/5/22)
        • From partial die cap
        • From elliptical clip coin
        • From elliptical strike clip
      • Internal partial brockage (CW 11/1/10)
    • In-collar/out-of-collar
    • From another denomination (ES May/June 2005; CW 8/1/21)
    • From another error coin
      • From wrong planchet error (CW 11/28/22, 6/12/23)
      • From mangled and crumpled coins (often multi-struck) (CW 10/2/23)
      • From weakly-struck coins (CW 11/20/23)
    • Flipover brockage (CW 4/23/12)
      • On obverse
      • On reverse
    • First-strike brockage
      • “Mirror” brockage (unexpanded, undistorted) (CW 6/13/11, 3/17/14, 5/6/19, 10/28/19, 7/11/22, 6/27/22, 4/10/23)
      • Distorted first-strike brockages
    • Mid-stage and late-stage brockages
    • By struck fragment (CW 6/11/12)
      • Aligned with opposite, die-struck design
      • Not aligned with opposite design
    • From struck die fill (very rare) (CW 8/20/18)
    • From thin pieces of metal (CW 7/23/18)
    • From large dropped filling (CW 5/13/19)
    • Multiple brockages CW 9/26/11)
      • From multiple strikes
      • From clashed cap
      • From multi-struck coin (CW 7/4/22)
      • From more than one coin in striking chamber
      • From coin trapped between die cap and planchet
    • Clashed cap strikes (CW 8/30/10, 11/21/11, 1/13/14)
      • From a late-stage die cap that clashed with the opposite die
      • From a uniface die cap that clashed with the opposite die
      • From an early-stage die cap that clashed with the opposite die
      • From a cap that was striking counterbrockages that clashed with the opposite die
      • From a flipover die cap that clashed with the opposite die (CW 1/13/14)

Counterbrockages

    • Full (CW 10/11/10)
    • Partial (CW 11/8/10)
    • In-collar/out-of-collar
    • Counterbrockage of obverse on obverse
    • Counterbrockage of reverse on reverse
    • Flipover counterbrockage (CW 4/19/21)
    • Early, middle, and late-stage counterbrockages
    • From another error coin
    • Brockage-counterbrockage combination (8 types) (ES Nov/Dec 2009; CW 11/12/12)
    • Multiple counterbrockages (ES March/April 2010)
    • On second strike
    • Rebound counterbrockage (always on 3rd strike) (CW 11/9/15)
    • Secondary counterbrockage (CW 4/19/21)
    • Grease-generated counterbrockage (CW 4/11/22)

Horizontal lipping (CW 11/30/15)

    • In conjunction with in-collar indents, partial brockages, and struck-through errors

Die caps (CW 8/6/13, 1/7/20)

    • Hammer die caps (usually the obverse die)
      • Raised design on working face
      • Brockage on working face
      • Uniface die caps
      • Complex die caps
    • Anvil die caps (usually the reverse die)
      • Cupped toward anvil die, hammer die, both dies at opposite poles, or expanded in the horizontal plane
    • Partial (off-center) die caps (hammer or anvil) (CW 1/17/11)
      • With cupping
      • Without cupping
    • Detached cap bottoms (ES March/April 2001, May/June 2001)
    • Clashed caps (CW 1/22/24)

Capped die strikes (generic — without identifiable images)

    • Struck by uniface die cap
    • Struck through late-stage die cap
    • Struck through cap-like obstruction
    • Struck through split or torn cap
    • Proportional de-expansion (both faces struck through die cap or cap-like obstruction) (CW 11/11/13, 5/28/18)

Struck by impaled die cap (CW 6/10/13)

Capped die doubling (doubling associated with capped die strikes) (ES Sept/Oct 2005; CW 6/18/12, 5/16/22)

    • Shifted/rotated cap strikes (ES May/June 2000, March/April 2012; CW 11/21/11)
      • Correctly-facing incuse design elements (CW 11/3/08, 6/28/10, 6/11/12, 10/19/15, 8/12/19, 10/23/23, 11/13/23)
        • Multiple sets due to several preceding shift-and strike event
    • Unexplained, close raised doubling
      • Expansion ripples
    • Incuse doubling surrounding raised elements (CW 8/24/20)

“Struck-through” errors

    • Struck through fragment
    • Struck through clipped planchet (ES Sept/Oct 2002; CW 8/25/14)
    • Struck through thin struck fragment (CW 6/11/12)
      • Face-up (normally-oriented incuse design elements)
      • Face-down (mirror-image design elements)
      • Trapped between planchet and opposite die (mirror-image design elements)
    • Struck through detached lamination flake (CW 2/7/05, 6/11/12)
    • Struck through clad layer
      • Clad layer unstruck
      • Clad layer previously struck
    • Struck through reeding (CW 11/14/16, 8/21/23)
    • Struck through split planchet
      • Obverse
      • Reverse
    • Struck through hardware (bolts, screws, washers, etc) (CW 3/7/11)
    • Struck through feeder (ES Nov/Dec 2005; CW 3/7/11)
    • Struck-through unidentified machine part (CW 3/7/11)
    • Struck through emery disc (CW 12/16/02)
      • 1986 Silver Eagles struck through emery disc (CW 12/16/02)
    • Struck through “grease” (die fill)
      • Assorted ingredients, textures, viscosities, and consistencies (smooth, coarse, stiff, viscous, etc.)
    • Filled dies
      • Single design element (CW 6/29/20)
      • Multiple design elements
    • Struck through bulging die filling (CW 1/16/17, 5/20/19)
    • Filled collar/obstructed collar (ES Jan/Feb 2006; CW 9/22/14)
      • With flange
    • Surface Film Effects (ES May/June 2003; CW 8/16/10, 6/11/12, 10/29/12)
      • Surface film doubling
      • Surface film afterimage
      • Surface film transfer
      • Surface film transfer with clash marks
    • Dropped fillings (ES May/June 2003; CW 8/16/10, 6/11/12, 10/29/12)
      • Isolated elements (dropped letter, dropped number) (CW 2/7/05)
      • Conjoined dropped fillings (CW 8/16/10)
      • Large, multi-element dropped fillings (CW 4/19/10, 8/16/10, 11/14/22)
      • Retained dropped fillings
    • Struck through floating encrustation (on second strike) (CW 1/18/16, 6/18/18)
    • Yanked-out fillings (CW 1/16/23)
    • Struck through miscellaneous foreign matter
    • Field-restricted struck-through errors (CW 11/18/13)
    • Split or torn in two by struck-thru object (ES Nov/Dec 2007; CW 3/7/11, 7/13/15)
    • Retained struck-through errors (struck-in errors) (CW 7/18/16, 1/25/21, 9/13/21)
      • Embedded dropped filling (see above)
      • Embedded die fill (shapeless)
      • Die fragment (CW 2/6/23, 3/13/23)
      • Scrap metal
      • “Staple” (bristle from wire brush)
      • Plastic (associated with bullion coins)
      • Metal foil
        • (Cu-Ni)? associated with dimes and nickels)
        • Copper foil (ES Nov/Dec 2007)
      • Rubbery material (from die cover?)

Uniface strikes (cross-classified with indents) (CW 7/30/12, 9/16/19)

    • In-collar (CW 12/5/22)
    • On second strike (CW 11/29/10, 9/16/19, 6/5/23)
    • “Augmented” in-collar uniface strikes (CW 9/14/20)
      • Out-of-collar
        • Centered
        • Off-center

Sandwich strike (coin struck between two coins or planchets) (CW 5/16/11, 10/31/16, 11/20/17, 5/28/18, 3/22/21)

    • Partial
    • Full
    • Between two struck coins
    • Between two planchets
    • Between a coin and a planchet
    • Between struck coin and obverse die cap
    • Between obverse and reverse die cap

Nested coins (CW 3/16/20)

Mated pairs (CW 11/9/20)

Bonded coins

    • pile-ups (clusters)

Strike clips (ES July/Aug 1999, May/June 2001; CW 6/15/15)

    • Vertical shear clips (V)
      • Sheared between die and collar alone
      • Sheared between collar and overlying planchet
    • Horizontal shear clips (H)
    • Tensile strike clips (T)
    • Concave strike clips (V, H, T)
    • Elliptical strike clips (V, H ,T) (CW 4/5/10, 12/5/22)
    • Straight strike clips (H)
    • Saddle strike/strike clips (H)

Detached reeding

    • From forced broadstrikes
    • From stiff collar
    • Torn-off fin

Coin shrapnel (“breakaway fragments”)

    • Angular
    • Crescentic
    • Oval
    • Circular or sub-circular
    • Semilunar
    • Irregular

Intra-Strike Damage (damage coincident with strike) (CW 5/30/11, 12/20/21)

      • Flat contact facet at 6:00 opposite off-center strike
      • Machine part impingement on unstruck portion of off-center coin (CW 5/25/15)
      • Ejection damage to edge of unstruck perimeter.
      • External struck-through errors (with cupping) (CW 3/25/19)
      • Concave damage opposite off-center strike (12/30/19)

Cupping (CW 12/7/09)

    • With and without collar scar
    • In a single strike
    • Associated with multiple strikes
    • With die caps
    • Cupping toward hammer die
    • Cupping toward anvil die
    • Expansion in horizontal plane
    • On unobstructed strikes (CW 3/18/19)

Impact-Induced Warping (CW 3/16/15, 1/13/20)

Malrotation Errors (multi-sides coins only) (CW 3/23/15, 11/8/21)

Proof edge lettering errors (generated during strike by segmental collar)

    • Weak edge design due to segmented collar not closing fully (wide seams)
    • Segments arranged in incorrect sequence (see Die Installation Errors) (CW 4/7/08)


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet