Harrisons printed their stamp by photogravure for almost all stamps until 1980. The House of Questa, Ltd., used photo-lithography to create their stamps from 1980 onwards. Since this was a period of many rate changes, there are many different printings. Some are easily identifiable by the rate or by the color alone, but others require more research. Most stamps are listed in the Scott catalogue as 15x14, however, the size is actually 14¾x14. Stamps from booklets are usually different.
The emblem (the item in the upper left consisting of a crown and a six-sided star bearing a severed hand) exists as two major types on photo-lithographed stamps. In Type 1, the pearls on the top of the crown are individually drawn. The hand has a thin to non-existent line separating the thumb extending downward into the palm. The left side of the hand is a smooth curve. (Figure 1). Type 2 emblems have two distinctive subdivisions. On both, the pearls are in groups, and the three pearls on the left are stuck together. On type 2A, the center pearl, directly below the cross, is not connected to the other pearls, the line on the hand separating the thumb from the palm is heavy, and the left side of the hand is straight until it curves sharply at the wrist. (Figure 2). Type 2B has the central pearl joined to other lines and pearls. The line on the hand ranges from thin to medium. (Figure 3).
Several different types of phosphor were used to activate automatic facing/cancelling machines. Some stamps have one phosphor band while others have two. The goal was for each stamp to have two phosphor bands centered on the perforations. Because phosphors are generally invisible in normal light, it is difficult for the printer to accurately align bands, causing the varieties. A total of twelve different arrangements of the bands have been seen. There are several types of paper including some where the phosphor is imbedded in the paper.
Improved printing technology brought changes. The most obvious is the syncopated perforation, or the large perforation missing two teeth. This was developed as an anti-counterfeiting measure. (Figure 4). Rather than just a circular hole, it is a vertical ellipse in shape with both vertical sides relatively parallel, although rounded perforations are known. (Figure 5).
Two different types of gum were used on the Machins. Polyvinyl acetate (PVA) is almost transparent, and is artificially colored with pale yellow-brown dye. In 1973, another artificial gum, Dextrin, was introduced. This too is also colorless and had a small amount of green dye added.
The Complete Deegam Machin Handbook, Myall, D.G.A., 1993, Deegam Publications.
Standard Postage Stamp Catalogue, Snee, C., Ed, Amos Media, Sidney, OH, Volume 3, various years,