Tagged United States stamps turn 50

By Michael Baadke

Linn's Fifty Years Ago feature on page 12 in this issue notes an important milestone in the history of United States stamps: the first public testing of airmail stamps with phosphorescent material applied to trigger stamp detection in automatic mail-sorting machinery.

Two examples of the 1962 8¢ Jet Airliner Over Capitol airmail stamp photographed under shortwave ultraviolet light. The original untagged stamp is at left. The version at right, issued in 1963, is tagged with phosphorescent material that gives off a reddish glow under UV light.

A UV light on the Pitney-Bowes Mark II facer-canceler would activate the luminescent material, and the machine would then detect the glowing stamp.

An initial option was to distinguish and separate mail franked with tagged airmail stamps from regular mail.

Tagging also made it possible for the sorting machine to properly orient envelopes and postmark stamps without human intervention.

The first publicly issued stamp in the U.S. Post Office Department's experimental test was the 8¢ carmine Jet Airliner Over Capitol airmail sheet stamp.

That stamp was originally issued on plain untagged stamp paper Dec. 5, 1962, and is identified in the Scott Specialized Catalogue of United States Stamps and Covers as Scott C64.

The catalog listing also includes the experimental tagged version, as Scott C64a.

The testing of the new process was explained in USPOD philatelic release No. 51, dated July 7, 1963:

"A small, black box added to the Mark II facer-cancelling machine will 'recognize' and separate specially-treated airmail stamps in the field tests. Engineers said the modification is relatively inexpensive. It was conceived and is being developed by Post Office Department research scientists working in conjunction with the National Cash Register Co., Dayton, Ohio, and climaxes experiments that have been going on for more than three years."

The release described the phosphor tagging as "an invisible, inorganic phosphor commonly used in creams, ointments and medicines."

Collectors were given instructions for obtaining first-day cancels for the test from Dayton. These Aug. 1, 1963, covers include the slogan "First Day of Use Luminescent Tagging" between the four killer bars of the postmark.

The USPOD news release included an amusing detail of the stamp tagging experiments: "Canada, England and Germany are among other nations using these new methods.

"Canada prints luminescent bars on its test stamps, in contrast to the U.S. experiment in overprinting the entire stamp. Bars are sufficient because Canadians affix their stamps right side up, and do not cock them or place them upside down as American lovers sometimes do as a symbol of affection. This is so because many Canadian stamps are portraits of the British monarch and no loyal subject would turn his Queen upside down."

The tagging program on U.S. stamps continues to evolve. Developments have included the use of different luminescent materials to tag stamps and postal stationery, and tagging mats that apply the material to the surface of stamps in blocks or different shapes.

Prephosphored paper was introduced in 1987 on United States Scott 2115c, the 22¢ Flag Over Capitol coil stamp with a small "T" (representing the word "test") centered in the stamp design's lower margin.

A look through the Scott U.S. specialized catalog will turn up details of numerous tagging varieties, such as Scott 3980a, one of the 2006 Flag and Statue of Liberty coil stamps, described in the catalog as "Prephosphored coated paper with surface tagging showing a solid appearance."

Stamp varieties that are supposed to be tagged, but on which the tagging has been inadvertently omitted, are cataloged as stamp errors.

The Scott U.S. specialized catalog provides additional information about luminescence on stamps in the catalog introduction, including an important warning about hazards associated with exposure to UV light, which can burn the eyes.

The 1963 tagging test was an obvious success, and stamp tagging continues today, not only on U.S. stamps, but on many issues from countries all over the world.