1991 29¢ “F” Plastic Stamp
Issue Date: January 22, 1991
City: Washington, DC
Printed By: Avery International Corp.
Printing Method: Photogravure
Perforations: Die cut
Color: Black, blue and dark red
Although the 'F' stood for Flower on the regular non-denominated stamps, it was purely coincidental that it also stood for Flag on the experimental ATM stamps. As part of the Postal Service's test program with Seattle First National Bank, these stamps were vended through selected automatic teller machines (ATMs) to determine their practicality and appeal.