The E-Sylum:  Volume 10, Number 50, December 9, 2007, Article 25

OLD PAPER MONEY AND COUNTERFEIT-DETECTING PENS

[In an item last week about counterfeit-detecting pens, I
wrote: "As noted in one of the earlier E-Sylum articles,
the counterfeit pens come with a warning which says they
don't work on money older than 1959."

Tom DeLorey writes: "The paper was indeed changed circa
1960, and the chemical properties of the older paper are
such that the ruinous marking pens do not work on them."

Dave Lange writes: "This is about the time that the BEP
transitioned from the wet printing process to the dry
printing process. It was phased in with the new series
notes, while older series were still being printed
simultaneously using the soon-to-be-obsolete technology.
It's very likely that all wet-printed notes will fail
the pen test."

[Last week I wrote that "... the pens are designed to
detect certain properties in genuine U.S. currency paper,
but they only work with relatively recent notes."

Joe Boling writes: "The counterfeit detection pens don't
look for characteristics of US currency - they look for
characteristics of paper that is NOT used for US currency.
Crane's product is sized with animal fat and glycerine.
Commercial bond paper is sized with starch. The pen is
an iodine solution. Iodine and starch combine as black.
If the pen detects starch on the note, it will react.
Older notes have been in circulation a long time - they
have had many opportunities to get contaminated with
something that will react to the pen.

"The date 1959 is not significant. I have a stack of
well-circulated notes that I loan to theater companies
as props for live performances. I just marked two 1928A
$1 silver certificates and a 1928F $5 US note - they did
not react. A 1928 $5 US note reacted mildly. A 1934A $10
Federal Reserve Note did not react; neither did a 1934A
$20 FRN or a 1934 $50 FRN. Nor did five different well-
circulated 1923 $1 silver certificates.

"I have found that after a few weeks, the yellow marking
of the pen will disappear from a genuine note, so your
readers who are offended by the markings just need to put
the notes away for a while."

[So that explains why you don't see far more bills in
circulation showing marks from the counterfeit-detecting
pens.  -Editor]

Joe adds: "Three days after having marked the notes
previously listed, the marks are invisible on most and
barely visible on the others, except under ultraviolet
light - under UV they are still prominent."

 OLD PAPER MONEY AND COUNTERFEIT-DETECTING PENS
 esylum_v10n49a23.html

  Wayne Homren, Editor

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