PART VI. Striking Errors:
Struck Through Errors:
Struck Through Grease:
Black, Crusty Die Fill:
Definition: A substance composed of grease, dirt, metal particles that has harden into crusty material that can and will fill the recesses on the die. The image below shows this substance adhered to the rim above the motto “IN GOD WE TRUST” on a 1960 D small date Lincoln cent. While this examples shows flakes of copper in the material mix, other denominations can show different metal (s) within that blackened material. |
The material shown above is more than likely responsible for the partial 4 digit in the date and the blurred S mintmark shown on a 1943 S Lincoln cent in the image to the below left. The image to the below right shows a faint 6 digit in the date of a 1960 D small date Lincoln cent and was probably struck through the same material type. |
The most famous “struck through a foreign object” occurred in 1922, when the same type material kept filling the recessed area of the mintmark on the working die for that year’s Lincoln cent. This resulted in a no “D” mintmarked Lincoln cent. The Philadelphia mint did not strike small cents during that year. Image is courtesy of Heritage Auctions. |
Yanked-Out Fillings
Part VI. Striking Errors:
“Struck-Through” Errors:
Yanked-out fillings
Definition: A plug of hardened die fill that sticks to a newly-struck coin and that is yanked out of a die’s recess as the hammer die withdraws or as the coin is ejected. The recess-shaped plug replaces, and occupies the same position as, the raised design element that should occupy that location. In that location we instead find a raised element composed of die fill (“grease”).
This 1969-D cent features a raised, black letter U in place of the normal raised U of TRUST. The black, crusty letter is a plug of die fill pulled out of the U-shaped recess in the obverse die face when the hammer die withdrew from the surface of this coin. Discovered by Matt Campbell.
Will’s tinker page
Ghost images (CW 8/1/11)
-
- Progressive, indirect design transfer (a.k.a. internal metal displacement phenomenon, ghosting, heavy design transfer) (CW 6/7/10)
- Worn clash marks
- Thin planchet (CW 8/2/10)
- Split planchet (CW 8/31/15)
- Split-before-strike (CW 8/2/10)
- Split after-strike
- Coin thinned by strike(s)
- Weak strike (CW 4/11/2011)
- High pressure strike
- “Greasy ghost” (CW 7/5/10)
- Surface film afterimage (CW 5/2/11)
- Surface film transfer (CW 5/2/11)
- Split plating afterimage (CW 5/2/11)
- Coarsened crystallite afterimage (CW 5/2/11)
- Slide zone ghost letters (11/16/15)
Doubling
-
- Die Deterioration Doubling
- Raised
- Incuse
- Machine Doubling
- Stutter strikes (3 types)
- “Abrasion doubling” (extremely doubtful) (CW 7/15/13)
- Split plating doubling (CW 3/26/12)
- Surface film doubling
- Grease-mold doubling (CW 8/19/13)
- Longacre doubling
- Offset laser-etched frosting on proof dies (CW 2/21/2011)
- Plating disturbance doubling (CW 3/28/2011)
- Flat-field doubling (imperfectly aligned proof strikes (CW 4/29/13)
- Die Deterioration Doubling
Embedded matter (CW 12/14/09)
-
- Poured-in
- Slag
- Intrinsic metallic inclusion
- Rolled-in
- Punched-in (by blanking die)
- Squeezed-in (upset mill inclusion) (CW 9/6/10)
- Scraped-in (CW 2/23/15)
- Struck-in
- Lettering die inclusion
- Poured-in
Edge overhangs (CW 11/30/2015)
-
- Partial collar errors
- Horizontal lipping
- Stiff collar errors
- Forced broadstrikes
Struck Through Floating Encrustation
Part IV. Striking Errors:
Struck-Through Errors:
Struck Through Floating Encrustation
Definition: A floating encrustation is a piece of compacted die fill or caked-on grime that enters the striking chamber and is struck into a coin. Stiff, caked-on grime can come from the bowels of the press. The lubricated joints and rods are a magnet for dust and dirt. This material can stiffen over time and then break off. Die fill (“grease”) is a compacted layer composed of lubricant, dirt, and metal dust that accumulates on the die face. Pieces can break away to form nondescript struck-through errors. In either case, the resulting struck-through error resembles a conventional “grease strike”.
The impression left behind by a floating encrustation can be expected to show:
- Soft or indistinct margins
- Variable depth (reflecting variable thickness of the foreign material)
- Variable topography (potentially smooth to rough)
- Occasional gaps or thin areas that allow the design to emerge.
There are only two practical ways to distinguish a floating encrustation impression from a grease strike:
- Assemble a progression (defined by die markers) that shows the sudden appearance of a struck-through area.
- Find a double-struck coin in which the first strike is unobstructed and the second strike is partly or fully obstructed.
This broadstruck 1994 Argentina 10 centavos shows an unobstructed first strike. The second strike was almost fully obstructed on the reverse face by what seems to have been a floating encrustation. The reverse face was struck by the hammer die. First-strike elements are flattened, but retain sharp margins. The only second-strike element to emerge is the C of CENTAVOS. The irregular texture and indistinct margins of the struck-through area are consistent with a floating encrustation.
This double-struck 2003 India 1 rupee coin shows an unobstructed first strike. The second strike was fully obstructed on the reverse face, which was struck by the anvil die. The minimal flattening of the first-strike elements and the variable depth and topography of the impression are inconsistent with a uniface strike against another steel 1 rupee planchet. I suspect a dollop of stiff grime entered the striking chamber and somehow found itself between the anvil die and the off-center coin on top. The subsequent strike flattened the crud deposit into a disc-like shape.
Weak Strikes
PART VI. Striking Errors:
Weak (Low Pressure) Strikes
Definition: A weak strike results from two proximate causes, inadequate ram pressure or insufficient die approximation (excessive minimum die clearance). Ram pressure is the tonnage applied to a planchet of normal thickness. Insufficient die approximation refers to the minimum approach the dies make to each other in the absence of a planchet. In many cases it is difficult or impossible to assign proximate cause. However, when a weak strike is accompanied by another error, or a weak strike progression can be assembled, the most common proximate cause appears to be insufficient die approximation. The dies simply don’t approach each other closely enough to leave a strong impression.
Ultimate cause is virtually impossible to determine. A weak strike could be due to a loose or cracked press frame, a loose or broken knuckle joint, a mistimed anvil or hammer die, a broken cam associated with either die, a jam-up in the guts of the press, a jam-up associated with an adjacent die pair, a broken circuit breaker, or simply dies that have fallen out of adjustment. A weakly struck coin could also be a test piece, otherwise known as a “die adjustment strike” or a “die trial”. Many weak strikes are labeled as such. But unless you were there the moment it was struck, there is no way to know. Therefore the terms “die trial”, “die adjustment strike”, “test piece”, and “set-up piece” should be abandoned.
Most, if not all weak strikes available in the marketplace appear to be the result of spontaneous equipment malfunction. The evidence for this is abundant and manifold.
- These errors are far too abundant to represent escapees from a test run. Test strikes are supposed to be set aside and consigned to the furnace for melting. You wouldn’t expect many coins to escape this fate.
- If these were test pieces, then you’d expect the greatest number of weak strikes to involve the denomination that is produced in greatest abundance – cents. However, weak strikes occur most frequently in dimes. That’s what you’d expect of weakness caused by spontaneous equipment malfunction. Dies that strike thin planchets have a very narrowly constrained minimum die clearance. If the clearance grows just a little bit, the strike will be weak. If the clearance shrinks even slightly, the dies are likely to clash. Thicker denominations have a much more generous clearance range. It is among these denominations that you’d expect to find fewer weak strikes, and this is indeed the case.
- Weak strikes can be found in association with a wide range of errors – double strikes, triple strikes, saddle strikes, misaligned die errors, clashed dies, indents, partial brockages, full brockages, struck-through errors, etc. Given how rare escaped test pieces are projected to be, multi-error test pieces should be as rare as unicorns.
- On multi-struck coins, a weak strike can immediately follow a strong strike and a strong strike can immediately follow a weak strike. Such rapid changes in die clearance (or ram pressure) would not be expected in a test run.
- Weak strike progressions can move in either direction – from weak to strong or from strong to weak. Such a progression can also show an erratic pattern of strengthening and weakening. That’s not what you’d expect of a test run.
- On saddle strikes, one off-center strike can be strong and the other weak. With respect to saddle strikes on previously-struck coins, the first strike can be weak while the two off-center strikes can be strong. The reverse situation has also been recorded. A weak first strike can then receive a saddle strike in which one of the off-center strikes is weak and the other is strong. None of these patterns is consistent with a test run scenario.
Weak strikes are sometimes confused with grease strikes – coins that are struck through a heavy layer of compacted die fill. It’s actually quite easy to tell the two errors apart.
- A weak strike will show a poorly developed or absent design rim. A grease strike will show a very well-developed design rim.
- A weak strike will retain some, most, or all of the planchet’s original proto-rim. The proto-rim is erased in a grease strike.
- A weak strike will retain the beveled rim/edge junction of the planchet. The bevel will be lost in a grease strike.
- The edge will be weakly struck and relatively narrow in a weak strike. The edge will be tall and vertical in a grease strike.
- Reeding will be weak or absent in a weak strike. Reeding will be very strong in a grease strike.
- In a weak strike, extent and pattern of weakness will be essentially the same on both faces. Uneven weakness is a hallmark of most grease strikes.
The photo below shows a weakly-struck 2007 Montana quarter. It was struck on a Schuler press, a model that doesn’t even require ram pressure and die clearance to be adjusted by means of a test run. The design rim is fairly well formed because state quarter dies have a relatively flat die face (very little die convexity).
Shown below is a 1983-D 5-cent coin with a weak second strike delivered by a rotated (25 degrees) and misaligned (26%) hammer die.
Images are courtesy of Heritage Auctions
Part X. Wastebasket / Composite Categories:
Ghost images (CW 8/1/11)
-
- Progressive, indirect design transfer (a.k.a. internal metal displacement phenomenon, ghosting, heavy design transfer) (CW 6/7/10)
- Worn clash marks
- Thin planchet (CW 8/2/10)
- Split planchet (CW 8/31/15)
- Split-before-strike (CW 8/2/10)
- Split after-strike
- Coin thinned by strike(s)
- Weak strike (CW 4/11/11)
- High pressure strike
- “Greasy ghost” (CW 7/5/10)
- Surface film afterimage (CW 5/2/11)
- Surface film transfer (CW 5/2/11)
- Split plating afterimage (CW 5/2/11)
- Coarsened crystallite afterimage (CW 5/2/11)
- Slide zone ghost letters (? 11/16/15)
- Incuse ghost images associated with capped die strikes (CW 10/25/21)
Doubling
-
- Die Deterioration Doubling
- Raised
- Incuse
- Machine Doubling
- Stutter strikes (3 types)
- “Abrasion doubling” (extremely doubtful) (CW 7/15/13)
- Split plating doubling (CW 3/26/12)
- Surface film doubling
- Grease-mold doubling (CW 8/19/13)
- Longacre doubling
- Offset laser-etched frosting on proof dies (CW 2/21/11)
- Plating disturbance doubling (CW 3/28/11)
- Flat-field doubling (imperfectly aligned proof strikes (CW 4/29/13)
- Die Deterioration Doubling
Embedded matter (CW 12/14/09)
-
- Poured-in
- Slag
- Intrinsic metallic inclusion
- Rolled-in
- Punched-in (by blanking die)
- Squeezed-in (upset mill inclusion) (CW 9/6/10)
- Scraped-in (CW 2/23/15)
- Struck-in
- Lettering die inclusion (CW 9/14/15)
- Poured-in
Edge overhangs (CW 11/30/15)
-
- Partial collar errors
- Horizontal lipping
- Stiff collar errors
- Forced broadstrikes
Green lettering – major heading
Blue lettering – linked to subject matter
Brown lettering – subject matter covered under that heading
Black lettering – no entry yet
Struck Through Dropped Filling
PART VI. Striking Errors:
Struck Through Foreign Objects:
Struck Through Dropped Filling:
Isolated Element (number, letter, etc.)
Definition: This error type occurs when compacted die fill (“grease”) falls out of a recess in the die face and onto a planchet. The plug of hardened material is then struck into the planchet, leaving an incuse impression of whatever design element the plug had molded itself to. Letters (“dropped letters”) and numbers (“dropped numbers”) are the most common elements duplicated in this fashion. If the plug remains next to the same die it fell out of, and if it doesn’t flip over, the dropped letter/number is oriented the same way as its normal raised counterpart. If, however, the filling falls against the opposite die or flips over, the impression is mirror-image. Most dropped fillings are normally-oriented.
This 1965(P) Lincoln cent shows a dropped letter A near the right base of the Memorial (black arrow). This dropped filling is from one of the three As found on the reverse die.
A more unusual dropped filling is found on this 2006(P) Lincoln cent. One of the urns on either side of the steps of the Memorial filled up with hardened “grease” and then dropped out. It landed on the stairs upside down and was struck into the planchet (black arrow). This dropped filling was verified by the use of overlays.
Part X Wastebasket Composite Categories
WASTEBASKET/COMPOSITE CATEGORIES
Ghost Progressive, Worn Thin Split planchets split-before-strike split Coins Weak High “Greasy Surface Surface Split-line Coarsened Other Doubling Die Raised Incuse Machine
Push “Slide doubling” (smeared Multiple machine doubling in one Machine doubling in more than Machine doubling on both faces One-sided, rim-restricted design Incuse
“Abrasion Split-line Surface Doubling Longacre Laser-etching Plating Other forms of Embedded matter (CW 12/14/09) Poured-in Slag Intrinsic Rolled-in Punched-in (by Squeezed-in (by
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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)
- Rotated die errors (CW 6/21/10, 7/9/12)
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)
- Misaligned collar
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
- Centered
- Uncentered (CW 7/20/15)
- Cupped broadstrike
- Forced broadstrike (CW 1/10/11, 11/30/15)
- Partial collar broadstrike (shows incomplete, tilted partial collar)
- 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)
- Partial collar (CW 2/24/20)
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
-
- Due to elevated ram pressure
- Finning (CW 8/23/04, 7/6/20)
- Encircling pressure bumps (CW 12/2/23)
- Due to elevated ram pressure or reduced minimum die clearance
- Due to stacked coins or planchets (CW 12/7/20)
- Localized, due to die tilt
- Due to elevated ram pressure
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)
- Skidding misalignment
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)
- Hammer die rotated (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”)
- Cupped off-center strikes
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)
- (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)
-
- With indent or partial brockage
- Between two indents or partial brockages
- With struck-through error
- Struck through clipped planchet
- With retained cud
Multiple strikes (CW 3/30/15)
-
- On-center/Off-center
- In-collar/out-of-collar
- Flipover
- Numerous closely-spaced strikes (ES Nov/Dec 2004; CW 1/11/21)
- Involving second die pair
- Delayed second strike (ES July/August 2007; CW 1/9/12, 6/13/16, 6/6/22, 1/23/23)
- Dual-date double strike (CW 6/13/16)
- Proof double strikes (CW 9/19/22)
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)
- Full
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)
- Hammer die caps (usually the obverse die)
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
- 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)
- Unexplained, close raised doubling
- Expansion ripples
- Incuse doubling surrounding raised elements (CW 8/24/20)
- Shifted/rotated cap strikes (ES May/June 2000, March/April 2012; CW 11/21/11)
“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.)
- “Greasy ghosts” (ghost images from grease accumulations) (CW 7/5/10, 7/10/17)
- Grease-mold doubling (ES March/April 2006, July/August 2006, Nov/Dec 2008; CW 8/19/13, 10/20/14)
- Grease-mediated radial smear (CW 7/31/17)
- “Spackled dies” (intentionally applied grease) (CW 10/18/21)
- Bifacial (5/22/23)
- 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
- Metal dust, shavings
- Cloth (CW 5/14/12, 12/3/18, 9/26/22)
- String (CW 3/9/20)
- Wire
- 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
- Out-of-collar
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)
- Vertical shear clips (V)
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)
- Spontaneous
- Forced
- By stiff collar
- By outlying disc of coin metal
- By foreign metal or machine part
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)