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The 20p Machin welcomes you to the Machin FAQ


All About Machins – The Machin FAQ
Part 2 – Identification

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12. Okay, here’s a challenging one. Since British booklets and coils have perforated edges on all sides, how can I tell a booklet or coil stamp from a sheet stamp?
13. Phew, that was a long one. Maybe this will be shorter. What is a screened value?
14. Tell me about the new gravure process, EME, that you just mentioned. What is it? How do I identify stamps printed that way?
15. Under construction.

12. Since British booklets and coils have perforated edges on all sides, how can I tell a booklet or coil stamp from a sheet stamp?

It’s easy. All it takes is a magnifying glass, and with a little practice you won’t even need that. But first, let me tell you that there’s an exception to the “all stamps are perforated all around” rule. Between September 1987 and April 1993, booklet panes were imperforate on two or three sides, but let’s leave that aside for the moment.

The way that you can distinguish stamps from booklets or coils is by looking at the perforations. Coils are cut apart during manufacture to make the long rolls, so two edges of the stamp are smooth. On a horizontal coil, the top and bottom edges are smooth; on a vertical coil, it is the side edges.

Booklet panes also have smooth edges that result from the web (the large continuous strip of paper that the stamps are printed on) being cut into individual panes during manufacture. Horizontally-oriented booklet panes have two rows of stamps. The top row has a smooth edge at the top, and the bottom row is smooth at bottom. The situation is similar for vertically-oriented panes, with smooth edges at left and right. The other edges, the edges not cut during manufacture, reflect the fact that the stamp was torn from its neighbors and are rough. This is illustrated below.

Besides the imperforate edge booklets mentioned previously, other exceptions are the panes in prestige booklets — with the exception of the first two of these booklets, the panes of six or nine Machins always have a margin around them, so there are no smooth edges — and self-adhesive booklets and coils, which have simulated perforations. There were also a few booklet panes that were manufactured by unusual processes and therefore do not have the expected cut edges. Myall mentions one of these towards the end of the interview that is linked below. Others are noted in his Handbook.

1/2p horizontal coil 1/2p sheet stamp 1/2p booklet stamp
1/2p horizontal coil corner 1/2p sheet stamp corner 1/2p booklet stamp corner
These three stamps illustrate how you can tell whether a Machin came from a booklet, coil or sheet. Below each stamp is an enlargement of the lower right corner. On the left is a Machin from a horizontal coil. The top and bottom edges are smooth, the result of the web being cut into coil strips. The left and right edges are rough as a result of the stamp being torn from its neighbors. In the center is a stamp from a sheet. All of the edges are rough. On the right is a very important stamp to be able to identify. It is the famous “half-penny left band,” one of the most expensive regularly-issued Machins. Its main identifying characteristic, and the one that makes it scarce, is the presence of a single phosphor band on the left side; the band can be seen in the image above. Another characteristic is the pattern of the perforation edges. The stamp was located at the bottom right corner of a booklet pane (see image below), so it was cut on the right and bottom sides. This is an important clue to the stamp’s identity, and it is useful in cases where the phosphor band may not be easily visible and there’s no ultraviolet light handy.


booklet pane containing 1/2p Machin with left band
This is a booklet pane from the 1972 Wedgwood prestige booklet. The 1/2p Machin with the left phosphor band is located at the lower right.

Machin booklet pane with imperf edgesThis method of identifying the source of stamps was first developed by Douglas Myall. He developed a nomenclature for it known as the “TCTC System.” To use this system, hold the stamp so the Queen’s portrait is upright. Label each edge, starting at the top and going clockwise. Each smooth edge that has been cut is labeled “C” and each rough edge that has been torn is labeled “T.” The horizontal coil above is cut at top and bottom, making it CTCT. The sheet stamp is TTTT, and the half-penny left band is TCCT. A stamp from the top row of a horizontally-oriented booklet pane would be cut at the top only, TCCC. A stamp from a vertical coil would bear the name of the system, TCTC. Myall’s comments about this system are here.

Myall’s notation systems are protected by copyright. Collectors are free to use them for their own write-ups, but they cannot be published in any form without written permission from Myall.

Now about those panes with imperforate edges. For many years, collectors had complained about booklet panes that had badly trimmed perforations. In fact, many panes were trimmed so badly that the perforations on one edge were completely trimmed off. In an attempt to satisfy these collectors, in September, 1987, Royal Mail started to trim two or three sides of booklet panes. One of those panes is pictured at right.

Royal Mail discontinued the practice in April, 1993. The stated reason was that the straight edges made it easier for counterfeiters to duplicate the stamps.

Note to the sharp-eyed reader: Do not attempt to use the TCTC method on illustrations of Machins on this web site. Many of the illustrations are photographically cropped from blocks, and many edges appear to be cut when in fact they are not. top


13. What is a screened value?

A stamp with a screened value has a screen of regular colored dots in the numeral and currency symbol. It is pictured below.

Screened and unscreened values on 3p ultramarine Machin
These images are taken of the values from two 3p ultramarine Machins. The value on the left is screened; the one on the right is not. Screening results from one of the production steps in photogravure being carried out improperly. Screening does not occur in Machins produced by lithography or the electromechanical engraving (EME) method used for nearly all Machins produced since 1997.

As noted in the Douglas Myall interview, the screen results from the improper execution of one of the steps of the photogravure printing process. A complete explanation is available in reference works such as Myall’s Handbook, but I’ll explain part of it here, based on Myall’s description:

Two master negatives are made from photographs, one of the portrait and and one of value. Each negative is projected many times onto a photographic plate using a step-and-repeat camera (thus the “photo” in photogravure). These plates are called multipositives because they contain multiple images.

The images are transferred from the multipositives to the printing cylinder by means of a carbon tissue. This is a gelatine coating on a film or paper base that is treated to be sensitive to light. The first step in preparing the tissue is to place an image of a screen on it by passing light through a cross-ruled piece of glass. The resulting screen pattern on the gelatine will form the walls of tiny cells on the cylinder. These cells will hold the printing ink.

The tissue then gets the design on it from the two multipositives, the value and the portrait, also using light. When the value is transferred, the multipositive should be fully exposed to the light so that the screen is overridden in the area of the value. This will result in no ink being placed on the printing cylinder in that area, so the value will appear white.

Underexposure to the light, however, results in some of the screen remaining on the tissue and, ultimately, visible in the value.

The degree of screening can vary depending on the amount of underexposure. Sometimes only part of a value will be screened. Other times, various changes over the life of the cylinder can obscure the screen, so some stamps produced from the cylinder will have the screen and others won’t.

Myall’s policy for the Handbook is to list only fully screened stamps, but obviously collectors may choose other examples for their collections.

Screening can also appear in the white border around the edge of a stamp and in the sheet margins (or selvage). These are caused by other variations in the printing process.

Screening only occurs in stamps printed by the original photogravure method. Stamps produced in this way are often called “acid-etched” because acid is used in the process of transferring the design from the carbon tissue to the printing cylinder. A newer gravure process, known as electromechanical engraving, or EME, was introduced starting in 1991. Stamps produced using EME do not show screening. top


14. What is the EME printing method? How do I identify stamps printed that way?

Electromechanical engraving, or EME, is a gravure process that replaces the photography, carbon tissue, and acid etching of the old photogravure process with an automated process that transfers the image to the printing cylinder with a diamond stylus or laser under control of a computer. There’s no photography involved, except perhaps in capturing the original artwork. The Scott catalogs still incorrectly refer to this process as photogravure, but other works correctly call it simply a gravure process. EME produces a sharper image than acid-etch photogravure. It was introduced gradually starting in 1991.

Sharpness of the portrait was also increased by the use of a new digitized image of the Machin head. This image was created by Harrisons in 1997 and supplied to other printers.

Machins printed by gravure processes can therefore be divided into three groups:

  1. Machins produced by the original acid-etch photogravure process.
  2. Machins produced by EME using the original image of the Machin head.
  3. Machins produced by EME using the new digitized image of the Machin head.

A 2p Machin from each of the three groups is illustrated below.

2p original photogravure 2p EME original portrait 2p EME digital portrait
These three stamps illustrate the three types of Machins printed by gravure. On the left is a 2p Machin printed by Harrison and issued in 1988. The original acid-etch photogravure process and the original image of the portrait were used for it. In the middle is a 2p Machin printed by Enschedé and issued in 1995. The EME gravure process and the original image of the portrait were used for it. On the right is a 2p Machin printed by Harrison and issued in 1997. The EME gravure process and the new, digital image of the portrait were used for it.

At the left is the 2p printed by Harrison and Sons and issued in 1988, well before the EME process was introduced.

The first stamp created using the EME process was the 18p value produced by Enschedé of Holland and issued on November 19, 1991. Enschedé then produced a complete set of Machin low values during 1993-96; these were all printed using EME with the original image. The middle stamp above is the 2p Machin from that set. If you look carefully, you can see that this stamp is sharper than the one on the left, but there isn’t a lot of difference between the acid-etch photogravure stamps and the EME gravure stamps that were made with the same image of the portrait.

Harrison’s first EME issue was the non-denominated second-class coil issued on July 8, 1996. This had the original image.

In 1997, as the result of a new contract from Royal Mail, Harrison reprinted the full range of low value Machins. All of these were produced by EME with the new digitized image. The rightmost stamp in this image is from Harrison’s 1997 issue. It is noticeably sharper than the two to its left, and there is much additional detail in the Queen’s portrait.

Walsall switched to EME in April, 1997, and Questa finally joined the group in December, 1998. Both printers used only the new digitized image for their EME printings. Therefore, all Machins issued after Questa’s changeover have the new, improved portrait.

It is evident from the images above that the biggest part of the improvement of the Queen’s portrait on the Machins came from Harrison’s digital image, not from the switch to the EME process. top

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