green patches on front
In 1969, Austrian Media reported that 20 Schilling notes with green patches
did appear in circulation. People believed them to be counterfeits.
This assumption, however, was rejected by Oesterreichische Nationalbank.
In fact it is a change of color due to chemical reactions. For the printing
six different brown shades were used with different chemical
A certain quantity of notes may have been exposed to a certain external
influence, be it by chance or intentionally. This exposure caused a chemical
reaction of several brown shades, changing the color from brown to green.
A probable explanation, for instance, is that someone delivered a garment to
a chemical laundry and the bills were forgotton to be removed from its
pockets prior the cleaning process.