The Rotary Process
Also in 1854 a "rotary process" was patented by William Bemrose and Henry Howe Bemrose. The Bemrose machine was designed as a rouletting machine. As such, it proved impracticable for stamp separation but in 1856 was successfully converted to a perforating machine by George C. Howard of Toppan Carpenter, stamp printers for the American Government. Both the stroke and rotary processes have been refined since then, but are basically still the ones in use in the 21st century. The key decision for the perforator is the spacing of the holes; if too far apart, the stamps will not separate easily, and the stamps are likely to tear, but if too close, the stamps will tend to come apart in normal handling. In a few cases the size of the holes has been a factor. In the case of certain stamps produced by Australia for sale in rolls rather than sheets (coil stamps) a pattern can be seen on the stamp's short side of two small, ten large and two small holes.
Read more about this topic: Postage Stamp Separation
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