Machin Terms

Here is an alphabetical summary of terms applicable to collecting Machins (i.e. Machin-speak - it is almost a language unto its own).

Term Description
ACP acronym: 'A' (or Advanced) Coated Paper. Under short wave ultraviolet light it is very white in appearance and gives a strong afterglow.

Stamps that only come ACP:

APS type of perforation; Ab Produktion Svenska, the initials of a Swedish firm which manufacturers perforators. APS perf holes are very round and sharp, with a clean edge. There may be traces of paper or gum left in the hole. See Kampf perf.

CB Centre Band - a single phosphor band applied down the centre of the stamp.

elliptical type of perforation; aka. syncopated.

FCP acronym: Fluorescent Coated Paper. A chalk coated paper with an added optical brightening agent. Slightly whiter appearance than OCP.

Stamps that only come FCP:

JET phosphor a phosphor ink contaminated with an inorganic type based on zinc sulphide used by other postal administrations whose stamps were also printed by Harrison. Used on certain stamps in 1973. It has a greenish-yellow reaction to long wave ultraviolet light.

Stamps that include a JET phosphor variety:

Kampf type of perforation. The holes are clean with sharp edges. See APS perf.

LB Left Band - a single phosphor band applied to the left side of the stamp.

lithography a form of printing which is based on the principle that oil and water do not mix. Firms using this method of printing include Waddingtons, the House of Questa, and Walsall Security Printers. (see Photogravure)

NVI acronym: Non-Value Indicator. In 1989, non-denominated Machins appeared. These simply carried "1st" or "2nd" indicators, denoting the class of service that was paid for.

In 1999, an "E" valued stamp was released - for the letter rate to Europe.

OCP acronym: Original Coated Paper. This is a chalk coated paper with little or no optical brightening agent. It is off-white or creamy and has a dull reaction to short-wave ultraviolet light. It was gradually replaced by FCP starting in 1971.

Stamps that only come OCP:

  • almost all of the pre-decimal values
OFNP acronym: OBA-Free Non-phosphorised Paper. A paper with no Optical Brightening Agents.

OFPP acronym: OBA-Free Phosphorised Paper. A phosphorised paper with no Optical Brightening Agents.

PCP acronym: Phosphor Coated Paper. This is a chalk coated paper incorporating a phosphor activator during manufacture. It has a dull appearance, giving a weak afterglow under short-wave ultraviolet light.

PCP1 has a strong afterglow and a dull matt appearance.

PCP2 has a very shiny appearance and strong afterglow.

Stamps that only come PCP: Stamps that only come PCP1:
photogravure a form of printing. A recess printing process which uses photography to produce multiple images from a master. (see Lithography)

POP acronym: post office paper. A term given to various chalk coated papers supplied by the Post Office for printing some early Machins by the recess process. It was replaced in 1973 by paper supplied Bradbury Wilkinson (sometimes referred to as "Contractors paper").

PPP acronym: Preprinted Phosphor Paper. Ordinary FCP paper was pre-printed with allover phosphor and then used to print stamps in the usual way. Short-lived, only used in October 1979.

Only three Machin stamps appeared on this paper:

RB Right Band - a single phosphor band applied to the right side of the stamp.

Security paper This is only applicable to mint self-adhesive stamps stamps. Some late-issue 2015-type security Machins, printed by Walsall, began including a light-grey 'wavy' text printed on top of the backing paper. It is visible between the mint stamps, and, when the stamp is removed from the pane/booklet, the full text is visible.

The stamp itself does not show any of this text. Thus, once the stamp is removed from the pane/booklet, the type of backing paper is no longer known.

Two types of text are known: (1) where all of the text reads 'upright'; (2) where some of the rows of text are inverted.

Screened value The values of the stamp design that are intended to be completely white in fact show a screen pattern (in the same colour as the stamp). This is due to the carbon tissue being underexposed to the screen during the photogravure process (preparing of the printing "plates").

Stamps that only come with a screened value:

shortbar a phosphor bar that does not extend the full height of the stamp. Click for a list and illustrations.

syncopated type of perforation; aka. elliptical.

Disclaimer: We apologize for any errors of information that might be present. Your feedback is appreciated.

For even more varieties on Machin stamps, check out The Complete Deegam Machin Handbook (simply the best Machin
 handbook available anywhere) by Douglas Myall - click for details.

Booklet pane numbers used courtesy the Modern British Philatelic Circle
who publish 'The Bookmark' Catalogue

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