The border of the 3-cent George Washington stamp was changed from the 1851 (imperforate) design to the 1857 #26 and #26A (perforated) designs primarily to accommodate the new perforation process.
The original 1851-57 plates had the stamps placed very close together, with thin outer frame lines (or none at all) separating them. When the U.S. began using rotary perforation machines in 1857 to allow for easier separation, these, the new perforations cut directly into the existing design, destroying the frame lines.
The redesign, resulting in Types II, IIa, and III for the 1857 issue, involved: Removing the Top and Bottom Frame Lines: To create more space for the perforations to cut through the paper without damaging the colored frame lines. Adjusting Side Frames: The side frame lines were often recut or allowed to extend beyond the top and bottom of the stamp to compensate for the missing outer border, as seen in Type IIa (#26A).
Key Differences Leading to #26 and #26A: #26 (Type II/III): Generally has the top and bottom frame lines removed, with side frames often extending down. #26A (Type IIa): Typically features more extensively re-cut or altered side frame lines, often including a "repaired" or modified top design due to the damage caused by the perforation machine.
