Evening star., 1926-09-26
Chromium MAKES BILLS
HARDER TO COUNTERFEIT
Thin Coat Applied to Plates for Print
ing Currency Also Increases
Life of Money.

therefore very dificult during and
just after the war, to meet the de-
mands for Liberty bonds and for an
increased supply OF paper currency.
Demand for currency has contin,
ued to increase: more bills are need
ed to pay increased prices OF mer-
chandise; money 10 detarioratsd s1s--s
rapidly by the sofled hands Of gAAp
line filing station employees. Other
methods Of reproducing the printing
plates were therefore investigated
Very faithful reproductions of en-
cravings can be made by electrodep-
osition. but such plates as are made
in electrotyping, or even plates con-
sisting OF a nickel surface. followed
by copper deposited to a. thickness Of
a quarter inch. would not Withstand
the pressures used in plate.printing.
"At the Bureau Of Engraving and
Printing 1t was discovered that by
depositing alternate layers sof nickel
and copper, a plate with the neces-
sary strength could be produced. This
| principle was employed in the electro
lytic plant designed In 1920 by the
staff of the Bureau Of Standards.
which has since been in successful
operation at the Bureau Of Engraving
and Printing.
Cheaper Than Steel Plates.
"Electrotyping plates are made
more cheaply than steel plates and
yield very fine impressions. Even
with the hardest nickel surface that
| could be produced by deposition. they
did not last aS long as the case-hard'
| ened steel plates; so it was desirable
to produce q harder surface.
"A study was then conducted at
the Bureau of Standards. chiefly by
H. E. Haring. upon the possibility
| Of applying chromium to these plates
1t was then known that chromium
| was very hard and subsequent tssts
have shown that, as measured by the
| width Of a scratch produced when a
diamond or a sapphire is~drawn across
It, 1t is the hardest metal thus far
examined.
| Although the deposition Of chro-
MUM was reported in 1854 by Bunsen,
and numerous papers have been pub
lished on this subject, no extensive
practical applications Of chromium
plating had been made in this coun-
| try up to 1924.
Process Proves Successful.
"Haring's work showed that to Oh
tain bright hard deposits. such as
would be suitable on a printing sur
face. the conditions Of plating nuss
| Dc CdISluHN COullOIleu. cSpSSldAlS 'uc
acidity and temperature Of the solu-
tion and the density OF the electrical
current.
LAS A result of this study. the
process was installed at the Bureau
Of Engra wing and Printing. and has
been. eminently successful. The i'm
pressions are somewhat sharper than
from the nickel or steel plates
"Chromilim is now attracting the
attention of many manufacturers. Its
possibilities lie i'm It's great hardness.
and hence it's suit ability for printing
plates. dies. gaises. cams and
gears: its high luster and resistance
to atmospheric corrosion. which has
led to its application. usually over
nickel plating. on automobile radiator
shells. bumper bars. plumbing fN
lures and other objects.
Through the studies Of chromium
plating now in progress at the Ru
reau Of Standards and in numerous
commercial research laboratories II
seems certain that within few year
II will become commonplace. instead
Of being A chemical curiosity