Die Abrasion (DAB)

Die abrasion marks are fine, raised scratches or polishing lines on a coin's surface that were transferred from the die during striking. These marks originate from the Mint's routine practice of polishing dies to extend their service life or to remove minor surface damage. Because scratches are incised (cut into) the die face, they produce corresponding raised lines on struck coins — the inverse relationship that governs all die-to-coin transfer.

Abrasion can also take design away. Polishing removes metal from the die face, and the die's design elements are recesses cut into that face. Polish deeply enough and a shallow element is simply gone: on the usual account, the bison's front leg on the 1937-D three-legged Buffalo nickel; a feather on the "two feathers" Buffalo nickels. The same operation that leaves harmless lines in a field will, pressed a little further, erase part of the design on every coin that die strikes for the rest of its life.

How Does It Happen?

Throughout the history of U.S. coinage, Mint personnel have polished dies as a standard maintenance procedure. The process involves abrading the die face with progressively finer materials — historically emery cloth, abrasive compounds, or polishing wheels — to smooth away minor imperfections.

The primary reasons for die polishing that produces abrasion evidence include:

1. Extending die life: As dies develop minor surface deterioration from repeated strikes, polishing removes the roughened layer and restores a smoother striking surface. A single die can produce hundreds of thousands of coins, and polishing at intervals significantly extends this service life.
2. Removing clash marks: When obverse and reverse dies strike each other without a planchet between them, each die picks up marks from the other's design. Polishing removes these clash marks so the die can return to service; Error-Ref shows a 1983-P Jefferson nickel whose dies were both abraded to remove a strong clash, leaving lines of varying length running in random directions.
3. Eliminating minor damage: Small die chips, surface pitting, or corrosion spots can sometimes be polished away rather than retiring the die entirely.
4. Proof die preparation: Proof dies receive extensive polishing to create the mirror-like fields that characterize proof coinage. This polishing is intentional and part of the proof manufacturing process, not a repair operation.

The abrasion marks left by this polishing follow the movements of the polishing tool. Error-Ref describes the scratches from intentional abrasion as fine and usually running in many directions, while accidental abrasion, such as a die face scraped repeatedly by a machine part, tends to leave straighter, wider, more uniform scrapes. On struck coins the lines are raised and most visible in the open fields, where there is no design to mask them.

When Abrasion Removes Design

A die is polished to take something off its face -- clash marks, pitting, a roughened surface. The design elements are recesses in that same face, and the shallowest of them sit barely below it. A pressman working on a damaged die removes the fault and, where the polishing runs over a shallow element, removes that too.

What follows is a genuine Mint product rather than damage, and the distinction matters for authentication: the loss is in the die, so it repeats on every coin that die strikes, and it is surrounded by the polishing lines that caused it. The imitation of the same coin -- and the best-known of these varieties are imitated -- is made by filing the detail off a common coin by hand. That version is unique to the one specimen, is surrounded by tool marks instead of polish lines, and displaces metal into the design nearby. See Altered Coin for how the two are separated in practice.

Design loss from abrasion is also distinct from a strike-through: grease or debris filling a die recess blocks one strike at a time and comes and goes within a run, while abrasion is permanent and progressive. If the detail is missing on every coin from that die and the surrounding field carries polish lines, it is abrasion; if it is missing on some and present on others from the same die, look at Strike Through.

How to Identify Die Abrasion

Die abrasion marks have specific characteristics that distinguish them from other surface marks:

• Raised profile: Because the marks are incised into the die, they appear raised on the coin's surface. Post-strike scratches on a coin are incuse (cut into the coin), which is the opposite.
• Pattern: Polishing lines appear as groups of fine lines, sometimes running in many directions, that sit only where the die was polished. Post-strike scratches are incuse and scattered wherever the coin was handled.
• Consistency across specimens: True die abrasion marks appear in the same location and orientation on every coin struck by that die. If you compare two coins from the same die pair, the marks will match. Contact marks from circulation are random and differ from coin to coin.
• Field concentration: Abrasion marks are most visible in the flat, open field areas of the coin. Design elements with relief often mask or interrupt the marks.
• Fine texture: Die abrasion marks are typically very fine — thinner than die cracks or die gouges. Under magnification, they resemble the hairline scratches left by a fine abrasive.

Die Abrasion vs. Hairlines

The most common confusion is between die abrasion marks (from the die) and hairlines (from cleaning or handling the coin after striking). The key distinction: die abrasion marks are raised above the surface, while post-strike hairlines are incised into it. A stereo microscope or strong magnification makes this difference clear. Additionally, die abrasion marks repeat from coin to coin struck by the same die, while cleaning hairlines are unique to each individual coin.

Notable Examples

Morgan Dollar Die Polish Lines

Morgan dollars (1878-1921) frequently display die polishing lines, particularly on later-state examples where dies were polished multiple times during their service life. The large, open fields of the Morgan dollar design make polishing lines especially visible. Collectors of Morgan dollar varieties document specific die states that show progressive polishing.

Accidental Abrasion on Modern Coins

Not all abrasion is maintenance. Error-Ref shows a 1998-P Washington quarter on which abrasion around the eye and nose removed shallow detail, including the inner corner of the eye, and left coarse, straight, parallel scrapes, most likely from a mis-timed feeder. It also shows a 1944 cent with a triangular abraded area on the reverse that nearly covers LURI in PLURIBUS, and notes similar damage on Lincoln cents dated 1917 to 1945.

Buffalo Nickels

Buffalo nickel (1913-1938) dies were often polished, and on many dates the polishing removed the small innermost feather of the headdress near the neck, sometimes with the designer's F below the date. PCGS reports that it recognizes 27 of these "two feathers" varieties and suggests the polishing was usually prompted by die damage such as a clash; NGC treats them as die states and does not attribute them.

1922 "No D" Lincoln Cent

In 1922 the Denver Mint struck the entire cent production for the United States, so every 1922 cent should carry a D. Three worn die pairs produced coins on which the mint mark is weak or absent. NGC attributes the loss to die erosion, perhaps with grease in the mint mark, while abrasion of the worn obverse is another explanation collectors give; the cause is not settled. The pair with a sharp, well-detailed reverse is the one the major services recognize as the full "No D," and the strong reverse is the diagnostic that separates it from the weak-D coins of the other pairs. NGC notes it is really a die state rather than a separate variety. It is also the best-known circulating missing mint mark, a page that sets it beside the dies that never received their mark at all.

1937-D Three-Legged Buffalo Nickel

A late state of a Denver reverse die on which the bison's front leg is almost entirely gone between the hoof and the thigh. The usual account, repeated by Walter Breen, is that a press operator polished clash marks off the die and took the leg with them; NGC and others argue that a badly worn, rusted die pair was repolished to smooth its eroded fields. The genuine coin keeps the hoof and often shows a row of small raised die-rust lumps under the belly and a rough rear leg; most imitations are four-legged coins with the leg tooled away. The Buffalo nickel "two feathers" varieties come from polishing on the obverse, where a feather was lost from the headdress.

Collecting Tips

• Die state significance: Die abrasion marks serve as important die state indicators. Varieties specialists use the presence, absence, and severity of polishing marks to identify specific die states in a die's lifecycle. Early die states will lack polishing marks, while later states show progressively more evidence.
• Grading impact: Die polishing lines are a product of the minting process, not post-strike damage, so they are not wear or cleaning; heavy polishing that removes design detail does change how a coin looks.
• Proof coins: On proof coins, die polishing lines are sometimes called "die lines" or "polish lines" and are a normal result of preparing proof dies.
• Attribution tool: Because die abrasion patterns are unique to specific die states, they serve as reliable attribution markers for variety collectors. Matching the polishing line pattern on a coin to published die state photographs confirms both the die variety and its state.
• Magnification required: A 10x loupe is the minimum for examining die abrasion marks. A 20x-30x stereo microscope is preferred for detailed examination, particularly when trying to distinguish raised die polishing lines from incuse post-strike hairlines.