Preservation and Care of Philatelic Materials
Subsidiary Page
17
Tagging Colors Varieties, and Tagging Changes Over Time
Tagging Colors and Varieties
Collectors who purchase tagged varieties, such as one tagging bar when there should be
two, are advised to be very careful. Zinc silicate and sulfide pigments, commonly used in
tagging, can be removed when the stamp has a portion of it boiled in water for two hours.
The boiling water will also slightly change the color of the stamp's ink.
Most postal systems use activated zinc sulfide for tagging. This fluoresces yellow green.
Most Swiss stamps and some Belgian stamps use activated zinc sulfide with a small amount
of copper. These stamps fluoresce a greenish yellow. When flours (dyes) are added to the
bleaching agent, the result is a fluorescence in golden yellow color. A combination of
tagging and bleaching agents will give a fluorescence of bright blue. Low concentrations of
copper fluoresce pink, while calcium silicate activated by manganese will fluoresce pink to
orange.
Alkalis are often present in phosphor inks to prevent polymerization prior to the printing.
After printing, the alkali is absorbed by the paper. The alkali should not harm the paper,
and it may add to its life by neutralizing acidity.
Tagging Changes Over Time
Some collectors see the various bars and coatings in their many sizes and luminous
characteristics as varieties. These characteristics do change over time. It is virtually
impossible to retain the tagging characteristics in their original condition. The early
tagging, when the use of various components was in its infancy, has already resulted in the
degradation of many of the tagging's component chemicals.
The long term effect of these changes on stamps is a major concern to collectors of modern
stamps. In addition to changes in the chemical components themselves, the tagging
materials can interact with the stamp paper and the printing inks. Collectors must wait
and see what the long term effects will be. So far, very few corrective measures have been
noted or identified to retard these changes.
END OF SUBSIDIARY PAGE 17
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