Following are examples of covers franked with eighteen cents postage.  The 18¢ rate period was very short, beginning on March 22, 1981 and ending seven months later on October 31. 

The original blue 5¢ Washington (Krause-Minkus 621, Scott 1283) was issued untagged in sheet form on February 22, 1966 during the 5¢ First Class rate period.  The tagged sheet version (Krause-Minkus 621z, Scott 1283a) was released a day later.  On September 8, 1966, a tagged coil (Krause-Minkus 636, Scott 1304) was issued.  Each of these three stamps, issued with shiny gum, depicted the first president with an unshaven look which caused much public dissatisfaction.

A revised "shaven" Washington version of the 100-stamp pane, also with shiny gum, was prepared and then released in November of 1967 (Krause-Minkus 646, Scott 1283B).

No coil stamps of the "shaven" Washington were released in 1967 as coils were used primarily on commercial mailings and there was no pressure from these large mailers for a new "shaven" version of the coil stamp.

What is unusual is that the unshaven Washington coil exists! 

It was not until 1981 that anyone was aware of a redesigned coil version of this stamp.  A strip of three, postmarked February 10, 1981, was found in a mixture by a collector (Scott 1304C, Krause-Minkus 747A).

Ken Lawrence (LINN'S, March 16, 1992 and American Philatelist, Aug., 1993) reported these redesigned coils were made for DAV purposes.  DAV prepared return response envelopes using these coils during the 15¢, 18¢, and 20¢ rate periods.  Other mass mailers are known to have used these coils during the same time period. 

Used in early March, the stamps on this cover were probably removed from a mass mailer's return envelope and used to enter a sweepstakes.