US Stamps

U.S. stamps with several colors but only one plate number

Mar 18, 2024, 10 AM

U.S. Stamp Notes by John M. Hotchner

A recent question from a reader has likely occurred to others. He sent the plate block of the 1983 U.S.-Sweden 20¢ commemorative (Scott 2036) shown in Figure 1. The stamp is printed in three colors — blue, black and red brown — but has only one black plate number.

Had this been 30 years earlier, multicolor printing would have required a different plate for each color. But in the mid-1950s, new technology was installed at the Bureau of Engraving and Printing (BEP). Called the Giori press, it used three inking-in rollers to ink up to three distinct areas on the plate. This allowed three colors to be printed from the same plate.

For examples of early Giori products, see the 4¢ American Flag and 8¢ Statue of Liberty stamps in Figure 2. They were issued in 1957 and 1958, respectively.

That same technology was used to print the U.S.-Sweden 20¢ stamp. An early problem was that different color inks might bleed into adjoining inks, usually in a minor way.

You can see that problem on the 20¢ plate block of four in Figure 1. Look at the intersections of color, such as the point between Benjamin Franklin’s jacket and the medal. You will see some degree of ink contamination as the blue has bled into the red brown just a bit.

There is another situation in which we see a single plate number on U.S. stamps printed in multiple colors. In the 1960s and 1970s, some U.S. stamps were produced on what was called a combination press. It allowed for distinct colors to be applied at multiple stations on a single press.

Typically, these presses would produce a stamp such as the 8¢ Stamp Collecting issue (Scott 1474) of 1972, shown in Figure 3.

On this stamp, the images of the 1847 5¢ Franklin stamp (Scott 1) in brown and the black magnifier were produced by an engraved (Giori process) plate, while the green and the black shading that darkened the design were produced by lithography.

All plates used were assigned plate numbers, but only the engraved black plate number (33850) made it onto the issued panes. Any other numbers were placed further away from the stamp design and were sliced off when the selvage was trimmed.

This was not a solution that made collectors happy. The United States Postal Service tried to overcome the problem by putting all the plate numbers in the margin, resulting in large plate blocks of six to 12 stamps with multiple full plate numbers.

See Figure 4 for an example, a block of 12 of the 1971 8¢ U.S. Postal Service Emblem stamp (Scott 1396).

Showing all the plate numbers was appreciated by collectors, until they noticed the additional cost and album space needed to collect these large blocks.

Eventually, the Postal Service and the BEP came up with the idea of using a code: a single number standing for a full five-digit plate number when printing multicolor, multiprocess stamps.

See the 20¢ International Peace Garden stamp (Scott 2014) of 1982 in Figure 5, on which “3” is the number for the plate that printed the engraved portion, and “2422” represents the four litho colors (yellow, red, green and gray) used to produce this stamp. The yellow “2” that precedes “422” is so light that it may not be visible in the picture.

This system of single-digit numbers representing longer plate numbers is still in use, with some modifications, today.

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