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Striking Errors
Broadstrikes: If the surrounding collar is pushed
below the surface of the lower die during the moment of striking, the metal of the coin
being struck is free to expand beyond the confines of the dies. The design of the coin is
normal at center, but as it nears the periphery, becomes distorted due to the uncontrolled
spread of metal.
Brockage and capped die strikes: If a newly struck
coin sticks to the surface of one of the dies, it acts as a die itself - called a die cap
- and produces images on succeeding coins. The image produced by any die is the direct
opposite on a coin, and brockages
Brockage |
are no different. Since the image is raised on the coin adhering to the die, the image
on the brockage is incused and reversed - a true mirror image. The first brockage strikes,
perfect mirror images and undistorted, are most prized. As additional coins are struck
from the capped die, the die cap begins to spread and thin under the pressures of
striking, distorting its image. At some point, as the die cap becomes more distorted, the
coins struck cease to be brockages and are known as capped die strikes.
Capped die strike |
While a brockage image is undistorted or relatively so, images on capped die strikes
are increasingly malformed. Although the image is recognizable, the design expands,
producing an image that can be several times the normal size. Finally, the die cap breaks
off or is pounded so thin it ceases to affect succeeding strikes. Sometimes, the die caps
fall off early and in a relatively undistorted state. Die caps resemble bottle caps, with
the metal wrapping around the surface of the die. Die caps are very rare and collectible,
much more so than capped die strikes.
Double and multiple strikes: Double strikes are
coins struck more than once. If the coin rotates slightly between strikes, but remains
centered within the coining chamber, two images will appear on both sides of the coin. The
first strike will be almost totally obliterated by the second strike, and the first strike
will be flattened and have almost no relief. Sometimes, a struck coin will flip - somewhat
like a pancake on a hot griddle - and fall upside down onto the surface of the die; thus,
the second strike has an obverse image obliterating the original reverse, and a reverse
image flattening the first obverse image. If the coin falls partially outside the dies
after the first strike, the second image is only partial.
Double strike |
The partial second strike obliterates the original image beneath it, but the rest of
the first strike is undistorted, except in the immediate vicinity of the second strike. A
saddle strike is generally not a true double strike, but usually the result of having a
planchet fall partially between two pairs of dies on a multi-die press. Saddle strikes
have two partial images, and an expanse of unstruck planchet between the struck areas,
resembling Mickey Mouse's head with the partial coin images representing his ears.
Examples of coins struck three, four or more times are known.
Filled die |
Filled dies: The Mint factory has its share of
dirt, grease and other lubricants, and metal filings. The recessed areas of the dies
sometimes fill up with a combination of this foreign material, preventing the metal of the
coins from flowing into the incused areas. This results in weak designs or missing design
details. The filled-die coin is one of the two most common types of errors. Filled-die
coins are a form of struck-through error (see later explanation).
Indented error |
Indented errors: An indented error is a coin struck
with another coin or planchet lying partially on its surface. The area covered by the
planchet does not come into contact with the die, and thus is blank if indented by a
planchet, or shows a partial brockage if indented by a struck coin. The most desirable of
the indented errors are larger coins with the indentation of a smaller planchet centered
on one side. Indented error coins are a form of struck-through error (see later
explanation).
Machine, mechanical, strike doubling: A form of
doubling, this is one of the two most common types of Mint errors. Some do not consider it
an error, but believe it to be a form of Mint-caused damage.
Mechanical doubling |
Most, however, believe it a true form of error coin. The cause is a looseness of the
die or other parts in the press which causes the die to twist as it comes in contact with
the surface of the newly struck coin. In twisting, the die drags the metal of the raised
designs to one side, creating the doubled image. The doubling is flat, like a shelf.
Off-center coins: If a planchet lies partially
outside of the dies during the striking, it receives an off-center strike. Each coin
struck off center is unique, but due to the large numbers available, are very inexpensive
in the lower denominations.
Off-center strike |
Off-center coins with dates are more valuable than coins without dates. Generally, on
dated coins, the greater the off-center strike, the more it is worth. Some collectors
collect off-center coins by their "clock" positions. Hold the coin with portrait
upright and look for the direction the strike lies. If it is at 90 degrees, the strike is
at 3 o'clock; if it lies at 270 degrees, the strike is at 9 o'clock.
Partial collar |
Partial collar: Often known as "railroad
rim" errors, the edge, not the rim, is the portion of the coin affected. It occurs
when the collar is pushed somewhat below the surface of the lower die, so that the upper
portion of the coin is free to expand beyond the confines of the collar, while the lower
portion is restrained. On coins struck from a reeded collar, partial reeding exists on the
area restrained by the collar. The error gets the nickname "railroad rim" from
its appearance - the coin, viewed edge-on, resembles the wheel from a railroad car.
Struck-through errors: Struck-through errors occur
when foreign objects fall between die and planchet during striking.
Struck-through
(wire bristle) |
Pieces of cloth, metal fragments, wire, slivers of
reeding, grease, oil, dirt, wire
bristles (from wire brushes used to clean dies, resembling staples), die covers and other
objects may fall between the dies and the coin. The most collectible struck-through errors
are those with the foreign object still embedded in the surface of the coin.
Weak strikes: Weak strikes often resemble coins
struck from grease-filled dies, but can be distinguished from those more common errors.
They occur either when the press has been turned off - it tends to cycle through several
strikings, each with less pressure than the previous - or when the press is being set up
by the operators who test the placement of the dies at lower coining pressures. On reeded
edge coins (like the dime and quarter dollar), weak strikes generally have poorly formed
reeding (it is strong on filled dies). Depending on the pressure used, the image may be
only slightly weak, or practically non-existent, or any stage in between.
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