We have discussed perforations in the printing of stamps. Now we will examine perforations in the collecting of them. Early collectors did not bother much with perforations. They separated the stamps by face difference and placed them in albums. The French set the standard for mastering perforations. When a stamp measures “perf 12,” that means tat there are twelve perforations for every 2 centimeters. But you do not have to count them. Perforation gauges can be purchased: these are made with lines and holes that show, when a stamp is placed on them, the precise gauge of the perforations.
Modern collectors pay a great deal of attention to perforations and they are a major determinant of quality. All of the perforation teeth are expected to be intact. Should any perforation tip fall below half of its expected length, as judged by the perforations around it, the stamp is referred to as having “nibbed perfs.” Should the perforation tooth be missing entirely, the stamp is said to have a ‘short” or “pulled perf.” Nibbed perfs generally decrease the value of an otherwise perfect stamp by about 25 percent, while short perfs can decrease the value by up to 50 percent.
United States stamps up through the 1930s were produced on a press that has been termed a flat press. A large sheet of paper is placed on the press, and the plate comes down to print the stamps. While this is an effective method of printing, it I not very speedy as each sheet of paper has to be placed on the press individually and then taken off again. In an era when stamp needs were small, this did not matter, and a good press manned y experienced printers produced enough stamps. In the late 1920s, the United States began to use a much speedier press, the rotary press, which prints using a curved plate on a continuously fed sheet of paper. Rotary printing eliminates the need for each piece of paper to be placed on the press individually. The long roll of printed stamps is then gummed, perforated, and cut into sheets.
All of this is germane to perforations because when a single sheet of paper is used to print a stamp, it is not necessary to perforate the edges of that sheet when the perforating step of the stamp production process comes along. The flat press-printed sheet is placed n the perforator, and generally the outside edges are left imperforate. These stamps with imperforate sides are called “straight edges.” Due to highly technical variances in printing on a flat press, straight edges can exist on one, two, or no sides, though data exists to tell us which is the case for each stamp issue. United States stamps were printed on a flat press until the late 1920s (and occasionally after that) and so exist with straight edges.
Straight edge stamps are not desired by collectors, for the reason that only the Great Collector knows, even though they are far scarcer than the fully perforated stamps. Accordingly, the morally feeble have discovered another way to line their pockets: buy a perforating machine, buy straight edge stamps, and perforate the side or sides that are straight edged.
Fortunately, reperforated stamps (as they are called by collectors) are generally not too difficult to tell. The first clue comes from examining the stamp carefully. Do all the rows of perforations seem to be even or does one of the rows cut at an angle? Government-applied rows are always parallel to each other, and it is surprising how few reperfers obey even this simple rule. Second, look at the perforation teeth themselves. When a normally printed stamp is torn apart along the perforations, it is never done completely cleanly. Most perforation teeth fray slightly, and there is a tendency for one or more teeth to be slightly longer or shorter than the others. Avoid stamps where the perforations on the side look flat, that is, where the perf tips all end at one place. Reperfers do their work against the flat, straight-edged side, so reperfed copies usually look this way.