One of the first things you will notice on a modern stamp is that the edges contain teeth. When stamps first appeared, they had plain edges. This is called imperforate (not Perforated Stamps). The stamps had to be cut from the sheet on which they were printed, with scissors or a knife, or even by means of tearing them apart.
It was due to Henry Archer, an Irishman, that perforation was applied to stamps. In 1847 he invented a machine just for this purpose. He wrote to the Postmaster-General stating what an advantage it would be if all stamps could be perforated (Perforated Stamps). His suggestion received approval, and after many experiments, his machine was never purchased, but his patent was and the first perforation machines were used in 1853. Perforations were also used to add information to stamp issues, e.g. Belgian stamps issued between 1893 and 1914, had a perforated tab or tablet added at the bottom or top of the stamp. In the two official languages, i.e. French and Dutch, the instructions were “Do not deliver on Sundays”.
Another process, called “rotating” was also tried. A rouletting (rotating) machine designed by William and Henry Benrose in 1854 was tried, but it did not work well, so it was converted to a perforating machine. It is a mixture of these two types of machines which was refined and machines based on these two processes are in use today. When one refers to “rouletting” it actually refers to small cuts in the paper instead of holes. Many countries used this system, but today this is seen on very few stamps.
To describe perforation, the standard is to count the number of holes in a 2 cm “span”. In the early 1950’s, the finest gauge (18 holes per 2 cm) was used on stamps of the Malay States and the coarsest (2 holes per 2 cm) was used on the stamps of Bhopal. Most modern perforations range between 11 and 14 holes per 2 cm. Coiled stamps are only perforated on one set of opposite sides, so that the stamps can be rolled into “coils”.
Today, perforations are important when regarding the condition of the stamp. Although it is possible to count the number of holes using a ruler, a perforation gauge is the most accurate way to count. Perforations can be clean cut or rough. Clean cut means that all the paper has been removed from the holes, whereas in rough perforations, portion of the paper has been left behind in the holes.
Many errors can occur in the perforation process. These are discussed fully in our article on Stamp Terminology.
Even though a stamp perforation may be incorrect or faulty, this should not be a reason for not collecting it. When a stamp has a high value in a catalogue, we assume that the stamp is rare or has an error. However, generally we do not know whether a stamp is rare or not. Now that stamps are being printed less and less, perhaps one day, that stamp you have with a faulty perforation, may be quite valuable.