Perfin, Commercial Overprint, Underprint
A perfin is a number of small holes in a distinct pattern, usually letters, applied through stamps used for postage or fiscal purposes.
Commercial overprints are printed on the front of stamps used for fiscal purposes.
Underprints are printed on the back of the stamps used for postage or fiscal purposes.
Before perfins
Perfins originated in Great Britain at a time when postage stamps were commonly used to pay small amounts of money and when they could also be cashed in at post offices, subject to a small commission. This made stamps an attractive target for theft by unscrupulous employees and many companies were looking for a solution.
In 1867, the General Post Office offered firms the chance to have their names printed on the backs of stamps before they were gummed, marking them indelibly, although this underprint was hard to see after the stamp had been stuck to a letter or document.
There was a considerable cost to companies using this scheme and only five ever adopted it. Some other firms arranged with general printers for their stamps to be printed with their names on the backs, on top of the gum. This was cheaper but less effective as a security measure because the overprints tended to dissolve once the gum was moistened.
Joseph Sloper is credited with inventing perfins.
In 1858 he had patented a method of indelibly marking documents by perforating them with small holes that formed letters and numbers as required to date, cancel or otherwise mark them.
In 1868 Sloper persuaded the General Post Office to allow the application of his invention to GB postage stamps, creating the first perfins.
The 13th March 1868 letter from the General Post Office authorising the use of perfins on GB postage stamps.
"The Postmaster General... desires me to inform you that, under the circumstances, he will not object to the perforation of postage stamps in the manner described by you, with a view to protect merchants and others, as far as possible, from the theft of the stamps used by them".
The 27th June 1870 letter from the Inland Revenue extended permission for perfins to be used on GB revenue stamps.
The originals of these letters are held in the Perfin Society Library.
This photograph shows the procession for Queen Victoria's Diamond Jubilee in 1897 passing Sloper's premises on the corner of Cannon Street and King William Street in the City of London.
Although other companies later started producing perfins, J. Sloper & Co. were the largest and longest lived, surviving until the 1990s.
Examples of GB perfins
Simplest GB perfin
3 holes
Most complex GB perfin
135 holes
Common early GB perfins
Great Western Railway
Common late GB perfins
Prudential Assurance Company
Inner London Education Authority
One letter or many
Some perfins are just a single letter, some contain many letters. Ampersands are often included.
Full name and monogram
Some perfins are full names rather than initials, while other combine the initials into a monogram.
Designs and numbers
While most perfins consist of letters, some are numbers or designs such as coats of arms.
Reversed perfin (right)
Caused by the sheet of stamps being folded before perforating.
These are often encountered, as are inverted perfins.
An example of a perforating machine used to produce perfins
Cataloguing perfins
All the perfins shown here might be described as "B&Co". But they are clearly different!
We can use slashes to denote a line break, so the perfin at far right would be "B/&/Co" but that still leaves us with three different B/&Co perfins in this small selection.
Counting the number of holes in each letter and measuring the height of the letters helps to distinguish between similar perfins.