Cataloging stamps requires a perforation gauge and watermark fluid

Apr 29, 2021, 5 PM

By Janet Klug

Being able to correctly identify stamps is an essential skill for any stamp collector. This includes stamps a collector already has and those on a want list. Basic identification skills enable a collector to properly place stamps in an album, prepare want lists and buy stamps with the confidence that what is being paid for is exactly what is received.

Collectors usually identify stamps by matching them with a listing in a stamp catalog. This is called "cataloging." Generally speaking, there are two types of stamp catalogs: general catalogs and specialized catalogs.

The Scott Standard Postage Stamp Catalogue is a general catalog. The ScottSpecialized Catalogue of United States Stamps and Covers and the Scott Classic Specialized Catalogue of Stamps and Covers 1840-1940 are specialized catalogs.

In the United States, most collectors use one or more of the Scott catalogs. Other notable catalog publishers include Stanley Gibbons (British) Michel (German) and Yvert et Tellier (French).

The type of collection you are forming will determine which catalog best serves your collecting interests.

Cataloging is a skill that can be learned. It goes hand-in-hand with other essential stamp collecting skills.

The basic characteristics used to identify a stamp include design, color and denomination.

Many stamps that have the same design, color and denomination can have greatly differing values depending on the gauge of the perforations or die cuts or the watermark. Two essential elements of cataloging are learning how to measure perforations and die cuts and how to identify watermarks.

What follows is a review of those skills, using only basic, inexpensive stamp collecting tools.

Perforations are the rows of holes punched between the printed stamp images in a sheet or pane. The holes weaken the paper and make separating the stamps from one another easy. The bits of paper between the holes are called "bridges" or "teeth." Die cuts are similar, but usually no paper remains between the cuts.

A perforation gauge is an instrument used to measure the number of holes or teeth per 20 millimeters (2 centimeters). Perforation gauges can be metal, plastic, film or cardboard.

The Linn's Multi-gauge shown in Figure 1 is made of a stable film that will not change shape with changes in temperature and humidity. The same gauge is sold today with the Scott brand name.

The see-through gauge allows the measuring of perforations of stamps that are on cover or are mounted in an album.

To measure the gauge of perforations on unmounted stamps, use stamp tongs to hold the stamp and then slide the edge of the stamp along the gauge lines until either the holes or the teeth match the lines on the gauge. Keep the stamp perfectly square with the gauge.

When the holes or teeth match the gauge perfectly all the way across, read the corresponding gauge.

Some stamps have compound perforations: the gauge of the perforations on the top and bottom (horizontal perforations) differs from those at the sides (vertical perforations). Stamp catalogs list the gauge of horizontal perforations first followed by the gauge of vertical perforations. A stamp listed as "Perf. 12 x 11" would have gauge 12 horizontal perforations and gauge 11 vertical perforations.

For most of stamp production history, perforations were the dominant method of separation, but other methods have been used, including rouletting and die cutting.

In rouletting, tiny slits are cut at intervals between the stamp designs.

Die cutting is primarily used on self-adhesive stamps. A sharp tool, called a die, is pressed into the paper to cut around the stamp design.

Since the late 1990s, die cutting has increasingly supplanted perforations as the method of separation for United States stamps. A perforation gauge can also be used to gauge rouletting intervals or the peaks or valleys of serpentine die cuts.

A watermark is an impression made in paper during its production. The impression can take the form of a geometric pattern; a symbol, such as a star, crown, or anchor; letters or numerals; or a combination of symbols and letters.

Some watermarks are visible from the back of the stamp without using watermark fluid. Others are visible when a stamp is placed face down on a flat, black surface or when it is viewed in front of a bright light.

For watermarks that are not so pronounced, watermark detection fluid or some other watermark detector must be used.

Watermark fluid is used with a tray. You can buy a purpose-made watermark tray or you can use a clean (preferably new and unused) black plastic or glass ash tray. The trays made for stamp collectors often have a spout to use to pour remaining fluid back into the bottle.

A bottle of watermark detection fluid and a watermark tray are shown in Figure 2.

Several brands of watermark fluid and several different styles of trays are available.

Most nonfluid watermark detectors are light boxes that use sidelighting and pressure to make a watermark visible. For beginners, watermark fluid is probably the easiest method to use.

To use fluid to detect a watermark, pick the stamp up with tongs and place it face down in the watermark tray. Dribble a few drops of watermark fluid on the stamp.

The watermark usually will become visible as soon as the fluid permeates the paper.

The most difficult watermarks to see are on stamps printed in yellow or light orange ink. Even experienced collectors have trouble with them.

Watermark fluid evaporates quickly, so pay close attention to the stamp when the watermark is visible and match it with a watermark illustrated in the catalog.

When you have identified a watermark, pour the remaining fluid back into the bottle and remove the stamp from the watermark tray. Place the stamp on a piece of blotting paper to dry before putting it away in a stock book or album.

Good watermarking fluid and good technique will not harm the gum on a mint stamp.

Once you can properly measure the gauge of the perforations on a stamp and make a correct identification of a watermark, you are ready to use a stamp catalog. A stamp catalog is more than just a listing of stamps by catalog number. A catalog offers much more information.

This information includes method of stamp production and printing; date of issue; gauge of perforations; watermarks; paper and gum varieties; colors and shade varieties; subject illustrated on the stamp; information on stamp grades and conditions; values for mint, never-hinged stamps, unused, hinged and used stamps; values for an on-cover stamp; and other pertinent information.

Some stamps are quite easy to find in a catalog using only the design, color and denomination. There is only one listing that could possibly apply to the stamp. Find that and you have correctly identified it. Once you identify a stamp, you can mount it in its proper place in an album.

Stamps you do not have but want are recorded on what is called a want list. Typically the list has just catalog numbers, but you can add perforation gauge, watermark and catalog value. Some collectors remove pages from an old catalog and use them as a want list.

The French New Hebrides 5-centime emerald Discovery of New Hebrides in 1606 stamp (Scott 94) shown in Figure 3 is an example of stamp that is easily identified by design, color and denomination.

This stamp is listed in Vol. 4 of the Scott standard catalog. Vol. 4 covers countries of the world whose names begin with the letters J through O.

According to the Scott standard catalog listing, this stamp was issued Oct. 20, 1956, to mark the 50th anniversary of the establishment of the Anglo-French Condominium of New Hebrides.

This stamp is printed on unwatermarked paper, which the catalog abbreviates as "Unwmk."

It was printed by gravure (or photogravure), abbreviated in the catalog as "Photo." In the same section, the catalog also lists three other stamps in the set that were issued on the same date, denominated 10c, 20c and 50c.

That's a lot of information for one listing in a stamp catalog, but because there is only one listing for a stamp that looks like this one, it does not take a lot of work to find it.

There is a stamp that is very similar: the British New Hebrides 5-centime emerald Discovery of New Hebrides in 1606 stamp (Scott 78). The two stamps can easily be distinguished from each other by their French or British inscriptions, respectively.

When there are more stamps with the same design listed elsewhere, the Scott standard catalog usually lists them by catalog number in a note after the initial listing.

More on cataloging will be included in a future Refresher Course.