Like many error/variety collectors (including me), John Shields likes
to gamble on eBay. The exercise involves finding a potentially rare or
valuable auction item that has been inaccurately described or so
poorly photographed that the nature of the error is hard to discern.
By such means Shields recently acquired a small, seemingly humdrum
lot of error coins. But one of the coins — described as an unstruck
planchet — looked like it might be of greater interest. Shields
noticed a series of curved grooves and a possible profile of Lincoln
on the only surface that was photographed. He thought it might be a
very weak strike, which would be a fine prize given the paltry sum of
money he paid. Once in hand, it proved more interesting than he could
The coin turned out to be an in-collar double strike with a 90
degree rotation of the coin between strikes. Both strikes were
exceedingly weak. Owing to the lack of details, I cannot determine if
both strikes were delivered by the same die pair (although it seems likely).
Strikes this weak have traditionally been called “die adjustment
strikes,” “die trials,” and “set-up pieces” in the mistaken belief
that these coins are escapees from test runs. But numerous,
independent lines of evidence indicate that the vast majority of weak
strikes in the marketplace are the result of spontaneous press
malfunctions that are often short-lived.
The temporary nature of such malfunctions is nicely illustrated by
double- and triple-struck coins in which all strikes are delivered by
the same die pair, all strikes are die-struck on both faces, but only
one strike is weak. Such errors are actually more common than
multi-strikes in which all of the strikes are weak.
One such error coin — a 2001-D Lincoln cent with an in-collar double
strike — was featured in the May 2, 2011, column. The first strike was
normal and the second quite weak. Subsequent study of microscopic die
flow lines demonstrated that the same die pair was responsible for
An even more exaggerated discrepancy in striking pressure is
displayed here in a 1999-D cent discovered by Robert (“BJ”) Neff. Here
again, the first strike was normal while the second strike was
exceptionally weak and rotated about 80 degrees counterclockwise
relative to the first strike. On the obverse, the only evidence of the
second strike is Lincoln’s facial profile. On the reverse, the second
strike is represented by small portions of the Lincoln Memorial’s
colonnade and steps. A tiny die dent shared by both strikes proves the
same die pair was responsible for both.
Any weak strike can be attributed to two proximate causes —
abnormally low ram pressure or excessive minimum die clearance. Ram
pressure is the tonnage delivered to a planchet of normal thickness.
Minimum die clearance is the closest approach the dies make to each
other in the absence of a planchet. For either malfunction, the
ultimate cause is conjectural, with many possibilities having been
offered over the years. The sort of instantaneous change in striking
pressure documented by the 1999-D Lincoln cent might be due to a brief
power interruption, a jam-up in an adjacent striking chamber, or a
broken machine part momentarily lodged in the press mechanism.
It would be very difficult to find an in-collar double strike in
which the first strike is weak and the second strong. The second
strike will inevitably obliterate the feeble first-strike details
unless they’re preserved in the form of a surface film afterimage. So
one must turn to coins in which a weak first strike is followed by a
strong second strike that is delivered off-center. This sequence is
seen here in a partially dated Lincoln cent struck sometime in the
1960s. Common die markers show that both strikes were delivered by the
same die pair.
The brief, self-correcting nature of some weak strikes was amply
demonstrated by a quarter dollar that appeared in the May 23, 2011,
column. In this coin the first strike was of normal strength, the
second strike was off-center and exceedingly weak, and the third
strike even more off-center but a very strong “stretch strike.” All
three strikes were delivered by the same die pair.