By Michael Baadke
The specialty of plate-block collecting was enjoyed for decades by many stamp collectors in the United States, but a combination of factors contributed to a decline in its popularity about 30 years ago.
As described in the past two Refresher Course columns, plate blocks are a specific group of stamps that are attached to one another as a single unit, taken from the side or corner of a pane. The blocks include the complete selvage (margin paper) that bears identification numbers for the plates used to print the press sheet from which the pane was separated.
The plate block contains at least one example of every design in the issue.
The smallest plate blocks consist of four stamps (two rows of two) with margin paper attached, although they can be larger and often are.
One factor that contributed to a decline in plate-block collecting was the development of se-tenant U.S. postage stamp issues.
Though collectors today are quite accustomed to stamp issues that include more than one design, such a thing did not exist in the United States before the 1964 5¢ Christmas issue, Scott 1254-57.
For the first time, four different U.S. postage stamp designs appeared together on one pane. While this particular se-tenant issue did not affect plate-block collectors since the plate block of four contained all four designs and the plate numbers, later se-tenant issues would grow considerably in size.
Issues with 10 different designs appeared in 1968 (6¢ Historic Flags, Scott 1345-54) and 1973 (8¢ Postal Service Employees, Scott 1489-98). Each of these issues required the plate-block collector to save 20 stamps to obtain every design in two rows with the necessary plate number information.
Two problems were quickly apparent. The big plate blocks once again cost much more than the smaller blocks of four, and they took up more than their share of room on an album page.
In 1976 the Postal Service issued the 13¢ 50 State Flags stamps (Scott 1633-82, shown in Figure 1), the first U.S. issue consisting of 50 different stamps.
What does a collector save as a plate block for this issue? The answer is everything you see in Figure 1.
To have at least one stamp of each design in the plate block, the collector needs to save the entire pane.
Multiple designs continue to be issued today by the Postal Service and large plate blocks are still the requirement in such cases.
Beginning with the 29¢ Legends of the West issue in 1994 (Scott 2869 and 2870), the Postal Service has regularly issued panes of 20 different stamps in what it calls its Classic Collections format.
These issues, including 1998's 32¢ Four Centuries of American Art issue (Scott 3236), must be saved as entire panes in the plate-block collection.
Even issues with fewer se-tenant designs, such as the five from last year's 32¢ Alexander Calder issue (Scott 3198-3202), require a large plate block.
A Calder plate block of 10 is shown in Figure 2.
The Postal Service made an attempt in 1980 to woo back plate-block collectors who had left the specialty by promising to eliminate the multidigit monster plate blocks.
In a press release dated Dec. 10, 1980, the agency announced a new plate numbering system that would, except in cases where more than four designs appear on a pane, "establish a plate block as consisting of four stamps regardless of the number of inks used or the press used to print the stamps."
The agency's Stamps Division said its goal was "to make plate number collecting a less expensive pursuit based upon logic and consistency."
The memo, two-and-a-half pages long, was attached to a 12-page report describing, among other things, how a gravure-printed single-design issue that had been printed with six five-digit number combinations along the selvage (each combination in a different color), would be printed henceforth with a single six-digit number combination (with each digit in a different color).
While the new system decreased the size of most plate blocks for multicolor issues to four, it did not change another printing press characteristic that affected a number of U.S. issues.
Stamps printed on the Bureau's combination intaglio-gravure A-press, which was installed in 1973, featured plate numbers that would appear virtually anywhere in the stamp margin.
Shown at left in Figure 3 are eight different strips of 20 9¢ Sylvanus Thayer stamps of 1985 (Scott 1852) placed one on top of another. A close inspection of the image shows the single digit "1" appearing in various positions in either one or two spots in the selvage of each strip.
These so-called floating plate numbers posed another problem for collectors who were used to saving corner blocks with selvage along two adjacent margins. The collector's initial instinct was to save all 20 stamps in the strip, but most catalogs today suggest that a plate block on these single-color floating number issues can be considered two rows of three stamps with the number centered in the margin paper.
An example of a plate block of six Thayer stamps is shown at right in Figure 3. Some collectors will recognize that this plate-block format closely follows that of stamps printed by the flat-plate method in the earliest years of the 20th century.
The floating plate number system was directly caused by the size of the A-press printing cylinder. The layout of the printing sleeve created 920 of these small-sized stamps, a number that couldn't be divided evenly into panes of 100 without waste.
In Linn's Plate Number Coil Handbook (published in 1990 and out of print), Ken Lawrence reported that not long after the Thayer stamp was produced, a change in perforating technology made it economical to reconfigure the A-press printing sleeves, and corner blocks of four stamps became the norm for these issues as well.
In the next Refresher Course we'll look at plate blocks on today's stamp issues, with one eye on the little diagram that is intended to tell collectors where their stamps came from.