Stamps And Perforation

This article is intended to give a general overview of stamp perforation relating to British stamps, without going into too many technical details:

George V era perforating machine

Stamps have been perforated by machines, with pins, for almost 150 years, although recent developments mean this no long applies. Today most stamp perforation is carried out by the ‘Swedish’ grinding method, which consists of a cylinder with small studs on it, and a grinding tool. The grinding tool rotates at high speed, grinding the perforation holes into a fine dust, which is extracted by vacuum, as the sheets pass between the cylinder and the grinder.

Traditional perforation was carried out on machines which had changed little since the first machine produced by Archer back in the 1850s. The perforating head consists of three basic parts, the Die Plate(2), the Stripping Plate(3) and the Pin Plate(4). The pin plate carries pins of the desired thickness in whatever configuration needed and may be for a single line of perforation, a complete row on a single pane, or on a double pane of two sheets side by side. Originally only a single comb was used and up to seven sheets could be perforated at a time. With continuous perforation, which came later, only a single thickness of paper was perforated.

The pins pass into the die plate through the stripping plate, which holds the sheet down during perforation and then ‘strips’ the paper from the pins on the return, hence its name, the paper passing between the stripping plate and the die plate. The base of the hole in the die plate is enlarged to allow free release of the perforated paper, which is collected in the base to be weighed as part of the check that all paper issued had been accounted for.

Diagram of perforating head

To ensure exact registration on all the main parts used in perforation (ie 2, 3 and 4) these were drilled from an original steel Master Plate, which was also used to produce any replacement parts that might be needed in future years.

Sheets were fed into the machine through the feed table by means of the Register Pins (illustrated). Two pin points were drilled in the supporting plate of the stamp printing plate, protruding slightly above the printing surface, and these pierced each stamp sheet during the printing operation. These points could be at each side of the sheet or top and bottom. Sheets were then pinned up to the matching pin points on the feed table to ensure exact register. Delivery grippers at the back of the machine gave movement to the stamp sheets, bringing each line of stamps into correct register with the perforating comb.

Continue to page 2 of this article »