Stamps incorporate many security features

May 1, 2021, 4 PM

By Janet Klug

Postage stamps are accountable paper. That means post offices must keep track of them just as they would keep track of cash or other types of securities. Stocks of stamps must be recorded, and sufficient receipts for their sales must be provided.

The world's postal services take accounting for stamps very seriously. Stamps that slip through the system represent lost revenue. Revenue is also lost when uncanceled stamps are reused, when cancels are chemically removed, or when stamps are counterfeited to defraud the postal system.

To protect their revenue, many postal services have experimented with methods to prevent illegal reuse or counterfeiting of postage stamps.

In the early days of stamps, this meant borrowing the security features found on contemporary paper currency, including watermarks, special paper and ornately engraved designs.

If you have ever noticed a ghostly design in a piece of bond paper, or held a newer $20 bill up to a strong light and seen a second smaller portrait of Andrew Jackson that appears to be imprisoned within the paper, you have seen a watermark.

Watermarks are made during the manufacture of the paper. On handmade paper, a watermark is formed when a design is created in wire and affixed to the screen upon which the paper pulp is gathered. This leaves a slight thinning of the paper where the wires are in the screen, forming a pattern.

Machine-made paper can have watermarks that are made by the dandy roll, a roller that presses the paper slurry when it is still about 90 percent water. Any raised design attached to the dandy roll while it is drawn across the wet paper pulp will impress the watermark design into the paper.

A watermark can often be viewed simply by flipping a stamp face down or viewing it on a black surface. If this simple method doesn't work, a little watermark fluid (commercial products are available) should bring the watermark out.

All sorts of special security features have been used for stamps. Granite paper has colored fibers or threads added to the paper pulp during the manufacturing. This makes counterfeiting stamps printed on this kind of paper much more difficult. The fibers also can add interesting and attractive texture and design elements to a stamp.

The 1-gulden dark blue Emperor Franz Josef stamp, Austria Scott 62, shown in Figure 1, is printed on granite paper.

Silk paper is similar, but the fibers of silk are finer. Sometimes an entire continuous length of silk thread is incorporated into the paper pulp.

The British embossed 1-shilling pale green Queen Victoria stamp shown in Figure 2 (Scott 5) is printed on paper with embedded vertical silk threads.

A very interesting type of security feature is two-ply paper. If someone tries to remove a stamp printed on two-ply paper from an envelope and reuse the stamp, the stamp self-destructs.

Security paper similar to the kind used for bank checks has also been used. Removal of the cancel leaves a very noticeable white spot on the security paper.

There was even an experiment to make stamps with a small amount of encapsulated gunpowder embedded in them, not unlike the roll caps or sticker caps used in the old toy guns children played with years ago. The idea was that when the stamp was struck with the canceling device, the charge would go off and destroy the stamp, making reuse impossible.

This security measure did not last long. Production costs were high, and the noise would have jarred the nerves of postal workers who hit the stamps with the canceler.

The U. S. Post Office Department introduced grilled stamps in 1867, such as the 1¢ blue Benjamin Franklin stamp shown in Figure 3, to thwart reuse. This process impressed a grid into the paper. The idea was that the grill would break the paper fibers and allow the canceling ink to penetrate fully.

Grills add a delicious complexity to U.S. stamps issued between 1867 and 1870. Many varieties can be collected.

The security devices discussed so far all relate to stamp paper, but some security methods involve printed features.

A fine pattern usually printed under the main design of a stamp is called burelage (pronounced byu-REL-ij). It is sometimes printed on the back of a stamp.

A 4-dinar+12d Christ and Virgin Mary occupation semipostal stamp, Serbia Scott 2NB10, with rose burelage on the front is shown in Figure 4.

Moire (maw-RAY) is a similar underprinted, overprinted or backprinted feature, but the printing is in a very distinctive wavy line pattern that looks like beautifully watered silk.

The 5¢ ultramarine King George V stamp, British Honduras Scott 87, shown in Figure 5, has a violet moire overprint.

Some stamps were printed on the reverse of very thin, nearly transparent paper called goldbeater's skin. If someone attempted to reuse the stamp by removing it from an envelope or document, the image would disintegrate. If you think of the way a decal works, you will get the idea of how these stamps were used.

Many modern stamps, including some from the United States, Great Britain and other countries, include microprinting as part of their designs.

The 45p T.S. Eliot Nobel Prize in Literature stamp, Great Britain Scott 1997, shown in Figure 6, has the entire text of T.S. Eliot's poem The Addressing of Catsmicroprinted on the pages of the open book.

Imaging equipment cannot capture the microprinting on such stamps, so forgeries of them produced by scanning would lack the microprinting.

Some stamps were printed using fugitive ink. The moment someone attempted to wash a cancel from a stamp printed with fugitive ink, the entire stamp image would disappear.

Various coatings have been used on stamps, although not all were security measures. Some coatings, such as phosphor tagging, are primarily used to trigger the mechanized equipment that faces and cancels letters in modern post offices. Luminescent coatings, however, also can work as a counterfeiting deterrent.

Chalk coatings have been used to treat the surface of stamp paper. This offers a similar benefit to that of fugitive ink. If an attempt is made to remove the cancellation, much of the design of the stamp goes with it.

At the turn of the 20th century, Austria began applying diagonal bands of varnish to stamp paper prior to printing to deter reuse of stamps.

The stamp was printed over the varnish. If someone tried to wash away a cancel, the part of the stamp design printed over the varnish would be removed too.

A 20-para on 10-heller rose Emperor Franz Josef stamp, Austria-Offices in the Ottoman Empire Scott 33a, is shown in Figure 7.

More recently many countries have begun putting holographic images on stamps. Besides being very cool to look at, these images that appear to be three-dimensional are also superb security devices. A photocopy or a color scan would just show the hologram in a flat, lifeless gray that is easily identified as a counterfeit.

The 65p Boron Atom Nobel Prize in Physics hologram stamp, Great Britain Scott 1998, is shown in Figure 8.

One stamp is crammed with more security feature per millimeter than any single stamp that came before or since.

In 1993, Great Britain issued its highest face-value stamp ever. This jumbo £10 Britannia stamp (Scott 1478) is shown in Figure 9.

Royal Mail obviously needed to protect this high-denomination stamp. The superb photocopiers available today make a high-denomination stamp a juicy target for those intent on committing fraud.

This £10 stamp was printed on granite paper with colored fibers that glow when exposed to ultraviolet light. In fact, putting this stamp under UV light is like transporting yourself into another world. The fibers in the paper glow in candy-color profusion. Britannia's shield glows as well.

Bands of multicolor microprinting that say "TEN POUNDS" cover the bottom fourth of the stamp and continue up through the design of Britannia. Queen Elizabeth's portrait is in silver metallic, and the £10 denomination is purple metallic.

Within the regular perforations are elliptical perforations, called syncopated perforations, on the top and bottom of the stamp.

If all of this was not enough, the Braille symbol for "10" is also embossed into the stamp.

It is a remarkable stamp to study and enjoy. It represents the culmination of some of the best security printing measures available at the time it was issued.

The next time you peruse your albums, see how many of these security devices you can spot. There is always much more to every stamp than just a casual glance reveals.