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Security
thread:
Security
thread is a thin thread or ribbon running through a bank
note substrate. All 1990 series and later notes, except
the $1, include this feature. The note’s denomination
is printed on the thread. Since it is visible in
transmitted light, but not in reflected light, the
thread is difficult to copy with a color copier which
uses reflected light to generate an image. Using a
unique thread position for each denomination guards
against certain counterfeit techniques, such as
bleaching ink off a lower denomination and using the
paper to "reprint" the bill as a higher value
note. |
