All three issues (Scott 544, 596 and 613) were rotary sheet waste perforated 11 in both directions on the flat plate perforating machine. It is unclear whether they were produced at the same time. Production quality and quantity was very low, due to the rotary press stamps' natural tendency to curl, and the use of the flat plate perforator for the slightly different-sized rotary printing.
Census of Scott 596, illustrated below and available at website at http://www.siegelauctions.com/dynamic/census/596/596.pdf , records thirteen used stamps. None is recorded unused. Only five of the thirteen have regular cancels. Of the non-precancelled stamps, two have major faults and one has poor centering. The stamp offered here and one other (Census No. 596-CAN-01) are the only two well-centered non-precancelled examples in existence.
Census No. 594-CAN-52. Ex Scarsdale. With 1950, 1994 and 2004 P.F. and 2006 P.S.E. certificates (VF-XF 85, SMQ $53,600.00). We were very surprised this only graded an 85 at P.S.E., which prompted us to compile our census of this issue. We failed to find a better copy -- none has graded higher to date. For some reason SMQ provides a $96,000.00 value for this issue in the grade of 90, which is misleading since none exists. We believe the 90 price should apply to the example offered here, based on its realization in the Scarsdale sale.