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Brief General Review of Perforations
This is a brief review of the aspects of perforations that seem relevant to Przedborz stamps, i.e. to methods that might have been used in Poland prior to the mid-1920's.1
It is based on the following sources, listed in no particular order:
Too late to be included in the initial writing of this section, I found some interesting websites:
- Short but intense conversations with my friend Herb Volin and with Roy Simpson of the UK's GBPS, with supplementary comments from Tim Burgess;
- Williams , Chapter 15, "Separation", which has 158 pages on perforations and related topics;
- Brett [1978a & b], which is a much shorter review of selected perforation terms that are most relevant to U.S. stamps;
- And of course, my own scans and observations, some of which are shown here.
The Austrian Philatelic Society of Great Britain has an interesting summary of perforation issues relevant to them, and interesting to us because Przedbórz was occupied by Austria-Hungary starting in about February 1915.
- Method of Perforating, or type of machine used.
Note: At this time, I have no idea what types of perforators might have been available to Panski, who printed the genuine stamps, but Williams  seems to suggest that at least some of the forgeries were single-line-perforated.
- Stroke, Flat-bed, or Guillotine Perforations.
This involves some mechanism so that all the perforating pins are applied at one time to an entire sheet of stamps. For example, all the holes in a column could be punched at one time, then the sheet moved ("indexed") so that the next line of holes would be punched, etc.
The first patents for this process were granted to Henry Archer, in Great Britain, 1848, although it sounds as if it took him a year or more, and several redesigns, to get the machine to work. (See Williams , pp. 646-653])
- Rotary Perforations.
In this method, the perforating pins are on a wheel that one way or another roles over the sheet of stamps, perforating the holes as it does so.
The first patents for this process were granted to William and Henry Bemrose, in Great Britain, 1854. They might have needed fewer redesigns than Archer. (See Williams , pp. 653-658]
- Pattern of Hole Production.
There are several types and subtypes of the pattern of punching the holes. (This wording is awkward, but may make sense if you keep reading.)
- Single-Line Perforations
One line of perforations is produced at a time, almost always using a stroke perforator.
- Multi-Line Perforations
A rotary perforator is set up with a number of wheels with perforating pins. One pass can perforate an entire sheet in one direction, and then a second pass can perforate the entire sheet in the other direction.
Single-, Double-, Triple-Comb Perforations (see Williams , pp. 700 ff., and see some of his illustrations below.)
A stroke perforator punches:
- Single-Comb: a line of stamps on three sides, so that when the sheet is indexed, the fourth side is punched along with the cross-lines in the next column.
- Double-Comb: one line of stamps on all four sides, and a second line of stamps on three sides.
- Triple-Comb: two lines of stamps on all four sides, and a third line of stamps on three sides.
- and you could have 4-comb, 5-comb, etc. We use the term Harrow Perforations when the combs perforate an entire sheet, as mentioned next.
- Harrow Perforations (sometimes called Frame Perforations)
This is a special case of comb perforation in which an entire sheet is perforated in both directions in one stroke.
- Depth of the Stack.
It was common to perforate several sheets at a time. Williams  illustrates (pg. 712) a Grover perforator punching seven sheets at a time, but this was after World War II. I imagine that earlier, 3-4 sheets was the norm.
Herb Volin has suggested that the variation in Przedbórz perforation quality is due to trying to punch too many sheets at one time; this must have been especially common when punching the forgeries.
Tim Burgess points out that in the major developed countries, such as the U.S., Great Britain and France, printers (of genuine stamps) were better trained and supervised. In such cases, rough perfs were more likely to arise from poor maintenance of the perforation machines. Examples might be bent or broken pins, chad not removed, etc.
- Shape of the holes
Most perfs have round holes, but some perforators punch holes that are oblong, oval or elliptical (e.g., Great Britain in the 1990's), square, rectangular (e.g. Schermack) or slotted.
- Hole Quality
Usually perforation holes are clean-cut, i.e., the paper has been entirely removed from the hole. However, holes can also have
- Intermediate Perforations, in which some of the paper has not been removed from the holes,
- Rough Perforations, in which much of the paper has not been removed from many or most holes,
- Blind Perforations, in which the paper has not been even cut or removed from the holes. This can be caused by broken or worn pins, clogged machines (there was no place for the paper to go), or too many sheets being perforated at a time. (The stack was too thick, and the bottom sheet or two didn't get punched.)
- Irregular Lines.
While genuine stamps may have perforation irregularities, forgery perforations are much more likely to be irregular. Williams  discusses several causes (pp 726-729).
- Irregular Hole Spacing
Sometime hole spacing is deliberately varied, as in Netherlands syncopated perforations, in which one or more holes are deliberately skipped. If the irregularity is NOT by design, then it suggests bent or broken pins.
Slightly uneven or wavy lines can also be caused by bent pins or misdrilled perforating plates or wheels.
- Uneven stamp margins
If some stamps margins are larger than average and others are smaller (as in Przedbórz stamps, especially forgeries), a single-line perforator was probably used.
- Freak or "wild" perforations include those going at odd angles, as shown in the Przedbórz #18 foldover error. They are discussed, for example, by Williams [1990, pp. 768-769], and by Boyarsky [2010, pg. 1047], who calls them "wild" perforations.
Examples of combs, from Williams 
Single Comb (left): This would perforate (for example) the right side, top and bottom of one column of stamps; when the final side was perforated, the selvage would be perforated as well.
Triple Comb: (right): This works the same way, but perforates three columns at a time, thus requiring fewer passes through the perforator.
Five-Comb: (right): This works the same way, but perforates five columns at a time, requiring even fewer passes.
A Harrow is a comb with enough columns to perforate an entire sheet in one pass.
Look at Przedbórz perforation samples
, or go back to varieties
1. The untested assumption is that most forgeries were printed in Poland no later than the mid- to late-1920's.
2. Ray Simpson points out that the perforating pins could become worn. After all, paper is a very abrasive material, although many people don't realize it.
Also note that perforating happens after the gum is applied; otherwise stamps would stick together when you tried to separate them. So it's easy to imagine the perforating machine getting sticky, dirty, and generally clogged up, unless it was cleaned very frequently.
Last modified 30 Nov. 2014