James Monroe’s portrait on U.S. #642 is based on a painting by John Vanderlyn and had been used previously on the 3¢ Louisiana Purchase issue. This was one of the first stamps issued featuring the new compound perforations. The first was the experimental 2¢ Washington just three months before. Perfecting Perforations on Rotary Stamps When the Bureau began printing sheets on the rotary press, they found 11 gauge perforations were too fine, causing the stamps to separate prematurely. This resulted in the perforations being changed back to 10 gauge perforations, which had first been used in 1915. Once again, objections were raised, and the Bureau began looking for a way to perforate the stamps so they were strong enough to resist premature separation, yet fine enough to be separated without difficulty. The solution was found in a compromise that resulted in a new perforation – the 10 1/2 gauge. This perforation seemed to please everyone and was adopted as the new standard for rotary press sheets. In the words of Linn’s author Gary Griffith, the 1926-28 Compound Perforation rotary stamps represent “if not perfection, then at least a high degree of achievement...”