Winnipeg Tagging on the 1967-1973 Centennial Issue
Tagging is of course, a chemical overprint that was applied to the surface of the stamps after printing. Like any overprint, there are several attributes which can show variation, and are worthy of study:
- The chemical makeup of the taggant compound used, as evidenced by its reaction under UV light.
- How much taggant was applied, as evidenced by how visible the tagging is to the naked eye, when the affected stamps are examined carefully.
- What the configuration of the tagging was on the stamps, i.e. how was it applied?
- What are the characteristics of the setting used, i.e. how wide are the tag bars and how far apart are they?
- Pale bright yellow
- Bluish white
- Pale green
- Brownish yellow
- Heavy - in which the bands are dark yellow and obvious.
- Moderate - in which the bands are light yellow. They are clearly visible to the naked eye, but are not dark.
- Light - in which the bands are barely visible to the naked eye.