Great Britain SG#NI25, NI26 1971-1993 Northern Ireland Regional Machin Heads, Two Lower Left Cylinder Blocks of 6 of the 8.5p and 9p Values

VFNH examples of two lower left cylinder blocks from this legendary definitive issue, which has become one of the longest running in the world. These are the Northern Ireland regional issues. Included are:

• 8.5p on FCP paper, 2 bands, PVAD gum, cylinder number 1 dot, and phosphor cylinder 21 (only visible under UV).
• 9p on FCP paper, 2 bands, PVAD gum, cylinder number 1 no dot.

This is NOT a completely in-depth lot, as are any of the Machin lots in this sale, as Gibbons Concise is still a very simplified listing of this issue, as compared to Deegam's Machin Bible. But, it will give you a chance to get your feet wet with this issue and to begin to learn the important differences between paper, printer, gum, perf, design type, and phosphor type, that together are so critical to an in-depth study of these stamps.

Gibbons cat for the basic singles is 4.80 pounds = $9.60, with cylinder blocks typically worth far more than singles. I don't have specialized catalogue for these, so you will have to decide how much more they are worth to you. The blocks offered here grade 80 and 84.

A Note About Paper used by Harrison & Sons in the 1971-1990's Period and the Machin Head Definitives.

In studying the Machin Heads, you first start with the following broad groups:

• Gummed stamps with standard perforations, and values.
• Gummed stamps with standard perforations and no value expressed.
• Gummed stamps with elliptical perforations and values.
• Gummed stamps with elliptical perforations with no values expressed.
• Self-adhesive stamps with no security markings.
• Self-adhesive stamps with source and time codes.
• Regional issues for Northern Ireland, Scotland, Wales and Isle of Man.

Once you are in each group, you then divide further by:

• Printing technique - photogravure or lithography.
• Printer - Harrison, Questa, Walsall, Waddington, Cartor or De La Rue.
• Perf. 14 or 15 x 14.
• Paper type, for the regular perf stamps - Original Coated Paper (OCP), Fluorescent Coated Paper (FCP) or Advance Coated Paper (ACP)
• Phosphor type - 2 side bands, once centre band, 1 right or left band (usually from booklets) or all over phosphor.
• Gum type, for the earlier regular perf stamps - PVA or PVA with added dextrin, also known as PVAD.

That's Machins in a nutshell.

The stamps during this period are printed primarily by Harrison and Sons by photogravure, with some issues being lithographed by House of Questa into the 1980's and later by Walsall and Enschede. Harrisons used three different types of white coated paper and two different types of gum, which were introduced over the life of the commemorative issues, and it is possible that issues that were current during the transition from one paper to another may exist on more than one type of paper, and with more than one type of gum. The three types are:

• Original Coated Paper (OCP) - The original coated paper has a slightly off-white appearance and the gum is a smooth, creamy PVA. Under UV the fluorescence level is generally very bright on the front, being at least MF or HF. On the back there is a wide range of fluorescent reactions from LF through to HB. On their own, most stamps look HB on the back, but it becomes apparent when you compare one stamp to another that there are some stark differences. Occasionally this paper will contain varying concentrations of fluorescent fibres.
• Fluorescent Coated Paper (FCP) - This paper is whiter than the OCP and glows very brightly under UV light on both the front and the back. By and large most stamps are HF or HB on both the front and the back. The gum is sometimes the original cream gum, but is most commonly the bluish green PVAD gum (PVA with added dextrin). FCP was introduced in 1974-1975. This paper never contains any fluorescent fibres, the fluorescence being uniform and clear.
• Advance Coated Paper (ACP) - This paper is similar to FCP, but is even brighter under UV. The gum is less bluish than the earlier PVAD, but is not the cream colour of the OCP. The fluorescence of this paper varies widely both on the front and the back, especially. In the early 1980's you can find LF and HB on the same issue, as well as a number of readings in between. The brightness of the chalk coating on the front varies from MF to HB, again with 2 or 3 different varieties on the same issue. By the 2000's the paper fluorescence becomes much more uniform.
• Phosphoriized Paper - phosphorized paper is similar to all over phosphor in the sense that there are no visible phosphor bands, but unlike all over phosphor, which does not extend all the way to the edges of the sheet, phosphorized paper has the phosphor built into the coating, so it is uniform throughout the sheet. Care must be taken not to confuse it with phosphor omitted stamps. Typically the former, will have a burnished, glazed appearance on the surface, whereas phosphorized paper will appear matte on the surface.