Foil Stamping
A relief and (or) a coloured image produced by stamping a metallized film or foil to the surface of the banknote. Due to high pressure, parts of the foil get into the paper making its mechanical separation practically impossible.
If diffraction foil is used, the image may change colour when the banknote is tilted (fig. 1).
a
b
Fig. 12. Foil stamping:
a – 50 Brunei Dollars (1996); b – 20 Bahamian Dollars (2006)