Design Elements	The letter “R” is an abbreviation for Right and was used to aid in mounting a plate either on the master or press cylinders.  As far as is known, the marking is only on plates for the Cottrell press, and is placed high enough up in the margin that it rarely survives the trimming process.    Very few examples had been found, all because of paper folds or off center perforations or sheet trimming.     An inverted capital 'R' on the Lincoln Sesquicentennial issue.    The marking seems to be unique to single color issues printed on the Cottrell presses.
Plate Identification
Production Markings
Inscriptions

 

 

                                                

SUBJECT REFERENCES

E. Elsworth Post, The Letter 'R' on a Printed Sheet of Stamps, The United States Specialist, Vol 34, March 1968, pg 107-108.   John S. Meek, Chrome Steel, Chrome, and “F” Markings, The United States Specialist, Vol 51, February 1980, pg 69-71.   Doug D’Avino, The Encyclopedia of United States Stamp Collecting:  Marginal Markings, The United States Specialist, Vol 75, September 2004, pg 389-406.