Avbstamps

Victor Bove, serving collectors since 1960

Luminescents on Stamps

Another type of tagging is "added to color" (AC) tagging. WIth these issues, tagging compound was added to the printing ink. Examples of AC tagging are Scott #1359 6¢ Erikson, #2443 15¢ beach umbrella, and many postal stationery envelope embossed stamps. AC tagging has been replaced by pre-phosphorous paper tagging and IT tagging.

Pre-phosphorous paper issues exist as two types - coated (CP) and uncoated (UP) paper. Both use identical tagging material, and only the paper differs. These formats were previously known as "surface tagging" and "embedded tagging", but the Scott catalog and Linn's now refer to these issues as "coated and uncoated pre-phosphorous paper." In order to better understand coated and uncoated pre-phosphorous paper differences, some background in the production of paper is necessary.
Paper is made from a slurry called "stuff." The stuff is spread over a moving belt made of wire screen. Next, water is drained from the stuff on the screen by suction, which forms a flat thin pulpy sheet. A Dandy roller then presses the paper giving it the desired texture. Wove or laid papers are a result of the wire screen the stuff is laid on and the surface of the Dandy roller. Watermarks can also be applied by the Dandy roller. The paper web is then pressed, dried, and sized, and a smooth finish coating is applied to coated papers only.

The final finishing coat in the case of CP tagging includes adding tag to the coating compounds and applying it to the paper's surface. Sizing (starch) is added to the paper to stiffen it and bind the rough surface fibers down so the paper remains flat, to better receive the printing ink. Odd sized paper is soft and fluffy like a blotter. The sizing compound completely penetrates the paper.

For uncoated pre-phosphorous (UP) paper, an insoluble tag powder is mixed with a binder such as varnish. This forms a colloidal liquid where the tag particles are suspended in the varnish. This mixture is then applied to the uncoated paper surface. Since UP paper has a rough surface, the mixture is absorbed into the paper unevenly and to varying depths. UP tag goes deeper into the surface of the paper than does CP tag. However, UP tag never comes close to completely penetrating the paper. If this occurred, tagging would be seen on the stamp's reverse side. UP tagging is always mottled.

UP tagging is easy to separate from both CP and OV tagged stamps. UP mottled tagging has a distinctive look that is unlike either grainy CP or mottled OV tagging. Study the examples that I have given as well as my illustrations of OV, and UP mottled tagging and you will see the difference. UP mottling has larger and more irregularly shaped bits of bright and dull tagging which correspond to the papers surface topography. Examples of type UP tagging are Scott #2184 29¢ Warren and Scott #2186 35¢ Chavez.

One final tagging type is image tagging (IT). With this tagging, only the stamps images are tagged, or untagged for the two early IT examples. The tagging, or lack of tagging, follows the contours of the stamps' image. Tagging is added after the images were printed for the glass stamps (Figure II). The remainder of the stamp is untagged. This untagged area allows for better absorption of the canceller ink, which helps prevent erasure of the cancel. Other than this security feature, block tagging serves the same purpose as IT tagging, and it's simpler to set up. As of March 2000, only the following were tagged by the IT method: Scott #1596 13¢ Eagle and Shield, #2385a 25¢ Classic Cars, #3328a 33¢ American Glass setenant, #3332 45¢ Universal Postal Union, and #3351 33¢ Insects. The last three stamps were printed by Ashton-Potter printers.


Stamps under ultraviolet (UV) light	Stamp under visible light

Figure II. IT tagging. Image only is tagged.

Another example of IT is Scott #2381-5 Classic Cars, where tagging was applied by the "D" press at the same time as the offset colors, but only to the white area beneath the cars (Figure III).


Stamp under visible light	Stamp under ultraviolet (UV) light

Figure III. Image taken under (SW) filter (UV) light

Scott #1596, the 13¢ Eagle & Shield, is another example of this, where the stamp is block tagged with the eagle and shield left untagged, a sort of a reverse type of IT tagging. The Classic Cars and Scott #1596 were early examples of this variety of IT tagging.