There are multiple of security systems used in stamps to prevent forgeries. Some of which I shall elaborate below:
- Types Gum
Gum Arabic - an all natural gum, commonly used until 1960s. It was mostly sourced from Sudan. However, this supply was constrained in early 1960s and so Harrison’s & Sons developed a new, synthetic gum Polyvinyl Acetate (PVA).
GA came back into the market later in 1969 and was used through to 1973 when PVA and later PVA Dextrin came into use.
The difference in the properties of these gums allows us to determine the authenticity of stamps, as I have described on a previous post.
- Luminescent
Another development that allowed the postal services to detect forgeries was the development of luminescent materials. These come with two different properties, they can either be phosphorescent or fluorescent.
Qatar has used at least two different a blue/white organic resin and a yellow/green Zinc Sulphide Copper complex.
There probably was a third one made by M/s Johan Enschede - Netherlands (Cartax DPXT) with a bright yellow fluorescence under UV light.
An interesting example of this is the 2005 Joint issue between Doha and Sarajevo (see image below).
- Watermarks
As I have also referred to in a previous post, watermarks were too used in British Stamps overprinted Qatar (both the ‘St. Edwards Crown and E2R multiple’ and the ‘St. Edwards Crown multiple’), later a good percentage of the stamps printed by M/s Johan Enschede, known as the JEZ watermark.
Other protections could be the thermochromatic ink, Gold Hotstamping, Gold metallic embossing. A variation (not necessarily a security feature) is Scent Varnish as on the 2008 stamps.
These, just a few of the many other features, also help make the stamps of Qatar highly interesting and collectable.
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