Coins struck from rusted dies show corrosion
Metal flows into die’s damaged areas
By Paul Gilkes
Among coinage struck
in the first century of the U.S. Mint's
full-scale operations, beginning in 1793, it is
not uncommon to encounter coins struck from dies
that rusted because of improper storage.
Some coins were struck for circulation from
those rusted dies.
Other pieces exhibiting rust contamination were
struck as restrikes at dates later than the date
on the coin, using uncanceled dies sold by the
Mint as scrap metal.
Examples of U.S. coins and restrikes produced
from rusted dies are known for gold, silver,
copper and copper-nickel issues from the 18th
and 19th centuries.
Coins struck from dies that are even slightly
rusted will exhibit evidence of the rust despite
efforts to remove the rust from the die or dies
The most commonly encountered evidence is the
often pebbly surface that will be on the coin in
the areas where the rust occurred on the die.
Sometimes, the rust evidence will appear in
large patches, depending on the severity of the
In some instances, die technicians attempted to
polish away the corrosion. However, evidence of
the corrosion often remained around the design
periphery, and in and around the digits in the
date and lettering.
Rust represents the remnants of corrosive action
of atmospheric contaminants on improperly stored
dies, effectively eating into and pitting the
When a coin is struck with a rusted die or dies,
the planchet's metal will flow into the
rust-eaten areas of the die, leaving raised
bumps or patches on the coin during the striking
process, giving that area on the coin a dull,
Coins known to have been struck with heavily
rusted dies exhibit greater evidence of the
corrosion, especially copper half cents and
Although suitable die steel was always at a
premium in the late 18th century and throughout
most of the 19th century, one would think it
would be requisite to protect the finished dies
from any handling or foreign agents that could
affect their usage.
Such was not always the case, Walter Breen notes
in his Complete Encyclopedia of U.S. and
Protecting the dies
Production during the earliest years of the U.S.
Mint's coin-making operations was fraught with
perils, most notably the annual yellow fever
epidemics that often plagued Philadelphia.
According to Breen, Mint operations often ceased
from August or September into late fall while
Mint personnel fled the city and the yellow
Before departing, Mint employees would place
dies into storage and make an effort to properly
The usual procedure, according to Breen, was to
seal all dies in hot fat or similar lubricant
for storage during the production impasse.
All dies would then be stored at the
Philadelphia Mint or the nearby Bank of the
United States before their next use.
In the haste to escape the yellow fever's annual
threat, though, the possibility existed that not
all dies received proper sealing treatment, or
any treatment at all, Breen explains.
After the fever threat was over, Mint personnel
would return to the city to resume coinage
If dies had rusted in the interim, they still
may have been judged acceptable by Mint
It wasn't the Mint's practice to
indiscriminately discard dies, even if rusted or
slightly cracked, if suitable production life
was still left in them, according to Breen.
Back in service
"Each winter, the old dies, or all that could
still be even briefly used, were retrieved from
the vaults, degreased and hastily combined in
any convenient pairings to make many small
batches of cents," according to Breen.
Similar procedures were followed to ensure the
protection of the die faces of all coinage dies,
regardless of the denomination or metallic
composition of the coinage to be produced.
Regardless of those efforts, though, coins
struck from rusted dies are known for all
denominations and compositions at least during
the first century of Mint production, with
scattered examples occurring during the early
An example of a coin that can be found struck
from extremely rusted dies is the 1876-CC Seated
Other notable examples can be found within the
Liberty Cap cent series, 2-cent series, Shield
5-cent coin series, Capped Bust quarter dollar
series, Indian Head gold $3 coin series, Coronet
gold $5 half eagle series, Morgan dollar series
and the 20th century Peace dollar series.
The extent of the rust on some of the dies is
such that resultant coins struck, not all or for
all denominations, have an almost matte finish.
Preventing dies from rusting continues to be
important for the U.S. Mint today.
Maintaining the dies is a huge task; the number
of dies, combined, used by each of the four Mint
production facilities – Philadelphia, Denver,
San Francisco and West Point – totals in the
thousands annually in the 21st century.
In the earliest days of the U.S. Mint, some
issues were produced with a total number of dies
that could be counted on fingers and toes.
Die maintenance today
More care is taken today to ensure that dies are
properly stored, and if there are problems, that
damaged dies are removed from service.
"Dies are stored in temperature and humidity
controlled vaults, and the face of the dies is
protected during shipment with protective soft
caps and light lubrication to prevent damage and
rust," according to a Nov. 13 statement released
by U.S. Mint spokesman Michael White.