Check watermarks to identify valuable stamps

Apr 30, 2021, 6 AM

By Michael Baadke

The watermark found in postage stamp paper can make a big difference in the process of properly identifying a stamp. Some postage stamp varieties occur when identical stamp designs are printed on different kinds of stamp paper.

One identifying feature of some stamp papers is a watermark. Collectors who encounter two otherwise identical stamps with different watermarks consider each stamp to be a separate identifiable issue. A watermark is a translucent impression in paper that allows more light through the affected area. It is created during the manufacture of the paper by the impression into the moist paper of a molded wire form known as a dandy roll.

Elegant stationery items often bear a watermark that features the name or insignia of the paper manufacturer. This type of watermark usually can be discerned simply by looking at the paper with a light behind it. Watermarks also appear in some currency, including the newly designed paper money of the United States first issued in 1996.

Stamp paper watermarks show various designs, letters, numbers and pictorial elements. Sometimes a watermark in stamp paper can be seen just by looking at the unprinted back side of a stamp. More often, the collector must use a few basic items to get a good look at the watermark.

Figure 1 shows actual photographs of watermarks in stamp paper. Each photo shows the back side of a printed postage stamp. At left is an 1895 stamp from Denmark, showing a watermark design of a single crown. The center stamp was issued by Trinidad and Tobago in 1936. It features multiple crowns and the cursive letters "CA" (standing for the stamp bureau Crown Agents). The stamp at right was issued by Italy in 1980. It pictures multiple five-pointed stars.

Each of these three photographs was taken while the stamp was placed in a black tray and saturated with a few drops of watermark detection fluid. Watermark fluid and trays can be purchased from stamp hobby dealers, either locally or by mail order. The fluid ranges in cost from $6 to $20 for a 3 oz. or 4 oz. bottle, depending on the brand purchased. Trays are inexpensive, usually costing no more than $2.

The chemical solvent in some watermark fluids must be handled carefully. Although most watermark fluids are nonflammable, prolonged breathing of the vapors can be harmful, and ingesting the fluid can be fatal. All warnings printed upon the label of the watermark fluid container should be followed carefully. Children should use watermark fluid only with the supervision of a responsible adult.

In recent years a new watermark fluid formula was developed at the request of the American Philatelic Society. Identified as Clarity brand fluid, it is advertised as nontoxic, though it also includes a cautionary statement.

The process of bringing out the stamp watermark is fairly simple. Place the dry stamp face down in a clean tray or dish made of black glass or plastic. Apply a few drops of watermark fluid directly to the back of the stamp, just enough to fully saturate the paper. Because the fluid evaporates quickly, look at the back of the saturated stamp and take note of the watermark pattern. Within moments, the fluid will evaporate, the stamp will be dry and you will not be able to see the watermark.

If you need to review the watermark, you can apply a few more drops of the fluid to the same stamp, repeating the process. The illustration in Figure 2 shows the application of watermark fluid. The bottle shown in the illustration is open because the fluid was being used at the moment the photograph was taken. Because the fluid evaporates quickly, bottles and containers of watermark fluid should be tightly capped whenever they are not in use.

Watermark fluid can be applied to either used or unused postage stamps. Although a stamp will have the appearance of being wet when saturated with watermark fluid, it will be unchanged after the fluid evaporates, which generally takes less than a minute. The watermarking process does not affect mint stamp gum.

Watermark fluid can also be helpful in detecting damage to stamps, such as thins in stamp paper, tears, creases or repairs. When saturated with the fluid, these flaws are much easier to spot.

The solvent in some early watermark fluids could damage the designs of some gravure-printed stamps manufactured with fugitive inks (ink that runs when immersed in certain liquids). Most of these issues, such as the 1933-37 series from Netherlands Indies, are so identified in stamp catalogs. Today's fluids generally describe themselves as safe for watermarking all stamps.

Not all stamps are printed on watermarked paper. In fact, most stamp papers today are unwatermarked. Most U.S. postage stamps issued after 1917 do not have watermarks. The last U.S. postage stamps to bear watermarks were issued in 1938.

Major stamp catalogs provide individual listings for stamps of similar designs printed on papers with different watermarks. There are many examples where the value difference between two similar stamps with different watermarks, or a watermarked stamp and an unwatermarked stamp, can be quite substantial. The stamp illustrated in Figure 3 provides one example.

The £1 black Windsor Castle stamp from Great Britain was originally issued in 1955 as part of a four-stamp set. Each stamp in the set bears the St. Edward's Crown and E2R multiple watermark, identified as watermark No. 308 in the 2001 Scott Standard Postage Stamp Catalogue. The 1955 £1 issue, Great Britain Scott 312, has a Scott catalog value of $110 in unused condition.

A second variety of the same stamp issued in 1959 was printed on paper with a different watermark, the St. Edward's Crown multiple (No. 322 in the Scott catalog). The 1959 issue is Great Britain Scott 374, and the unused stamp has a catalog value of $8.

A final issue of the Windsor Castle stamp appeared in 1967 on paper with no watermark, Scott 528. It catalogs unused at $3. The catalog illustrations of the two watermarks and the catalog listings for all three stamps are shown in Figure 3. The colors, printing method and perforation measurements for all three stamps are identical. To positively identify the £1 black, the watermark must be checked.

The word "multiple" used to describe the British watermarks in Figure 3 means the paper has a repeating watermark design that appears across each stamp. When just one watermark design appears on each stamp, as shown on the Danish stamp at left in Figure 1, it is simply known as a single watermark.

There are also "sheet watermark" stamps, where a single design covers an entire sheet, and each stamp bears only a portion of that one design (or sometimes, no portion at all).

Watermarks are most frequently read from right to left, meaning that symbols or text, when viewed in the watermarking tray, will look back-ward. That accounts for the reversed "CA" lettering on the Trinidad and Tobago stamp shown in Figure 1, center.

Errors and varieties of watermarks include reversed watermarks that read from left-to-right, watermarks that are inverted, watermarks that are both inverted and reversed, and watermarks that are sideways that are supposed to be upright.

Even using the simple watermarking method described here, it can be difficult to distinguish some watermarks. Watermarks on stamps printed in yellow and orange can be particularly difficult to see. Viewing the saturated stamp through a transparent colored filter can help in some instances. Some experts recommend using a filter that closely matches the color of the stamp design.

Other watermarks are simply very faint and are difficult to distinguish under any circumstances. The watermarks on some U.S. stamps appear on only a small corner of the stamp and can be hard to spot.

Some collectors have used cigarette lighter fuel to detect watermarks, claiming that the fluid is less expensive and causes no harm to the stamps. There are several drawbacks, however. Lighter fuel is a flammable product manufactured with the chemical naphtha. It may leave a filmy residue on stamps and its smell is awful. While it is inexpensive, lighter fuel is not designed for detecting watermarks on stamps, and it is not recommended for that purpose.

A few mechanical devices also are used by collectors to detect watermarks on stamps. Such devices may be handy to have at stamp club meetings and shows, for they can be used without the application of watermark fluid, which is best done at home. Collector reactions to these devices vary. While some prefer them because the need for watermark fluid application is eliminated, others have said that they are less reliable than the fluid method for revealing the watermark design.

Watermark detection is a very basic part of stamp identification. Your stamp catalog will serve as a guide to distinguishing similar stamps that are marked with different watermarks.