Design Elements

'F', a marginal marking punched on flat plates, is usually located to the left of the UR plate number, indicating that the plates had been hardened. At the time that the use of the F’s started, it was customary to initial work on steel plates with punched initials. The siderographer put his initials in the lower left corner, and the plate finisher put his initials in the lower right corner. Printers stamped their initials in the margin, resulting many times in long string of initials extending the length of the vertical margin. Frank Martie indicated that the hardened plate was approved by stamping his single initial on the plate. He started this practice on May 9, 1919 with plate 8168.

While one stamp will often show the F and plate number, the F is often entered far enough to the left (or right) to require a pair to show both.  This letter was usually added to the left of the plate number on the upper right pane, but can be found in other positions.  

Between May  20, 1918, plate number 8187, and November 18, 1918, plate number 9119, a small size "F" was in use.

The last use was on the Presidential dollar values in 1938.  

Plate Identification

Production Markings

Inscriptions