1917-19 20¢ Franklin
U.S. #515 was current for six years and went through numerous printings. That resulted in at least 11 shades, ranging from pale aquamarine to deep grayish blue. The stamp was used in combination with others to pay for heavy or foreign destination mail.
Flat Plate, Perf. 11
The Bureau of Engraving and Printing continued to use the 10 gauge perforation machines on flat plate stamp sheets even after 11 perf. stamps proved successful. In an effort to save money, they used the perf. 10 wheels until they wore out. Beginning in early 1917, stamps produced on flat plate presses were given 11 gauge perfs.
That marked the beginning of the flat plate perforated 11 Series of 1917-19 stamps. Perf. 12 had proven too flimsy, and perf. 10 was too difficult to separate without damaging the stamp, so perf. 11 became a satisfactory solution.
Issue Date: May 1917
Printed by: Bureau of Engraving and Printing
Method: Flat plate, using plates of 400 with four panes of 100