Plate blocks of the U.S. IGY stamp

First off, I want to give kudos to the library staff of the American Philatelic Research Library at the American Philatelic Society. I re-joined this group last year after a hiatus in my membership. I have already found it useful in a number of ways. One thing you can do is search the bibliographic databases of the library, and order articles or even books in its holdings to be emailed or sent to you. Staff members Scott Tiffney (Director of Information Services/Librarian) and Sarah Berezenko (Library Assistant) have sent me pdfs of a couple of key articles for this post.

The term plate block refers to a group of stamps from a sheet that are still attached to each other and bear the serial number of the printing plate in the sheet’s margin (the selvage). A block most often, but not necessarily, means a group of four stamps.

When I was a young stamp collector, I collected plate blocks, which was popular back then. Here is one page from my stock book, of blocks that are over 55 years old.

Plate blocks I collected in the 1960s

Unfortunately, I was not careful about how I stored these. The pressure of overlying weight over the years have pretty well glued these into my stock book. Oh well ... I've been more careful with my recent acquisitions. 

One of the articles that I requested and received from the APS was titled "Plate block collecting,"  by Barry Krause, from the September, 1996, issue of Global Stamp News, p. 26-29. Krause explains that U.S. stamps are printed in sheets, usually with four panes to a sheet. If you go to the post office, and ask for a "sheet" of stamps, what you are really getting is a pane. The relationship between a sheet and its panes is shown for the 1962 Project Mercury stamp in the figure marked as "full press sheet" on this web page from the Smithsonian National Postal Museum. The plate numbers are small, but you can see one per pane, from each of the four corners of the sheet.

Below is a pane from my collection of the U.S. IGY stamp. There are 50 stamps in this pane, hence 200 in the sheet, as mentioned in the specs for this stamp from an earlier post. There is a small strip of the selvage at the top, and a wider strip on the left side. The plate block number is shown in the lower left corner. The corresponding plate block is outlined in blue. As also mentioned in my earlier post on U.S. Scott #1107, this was the fourth U.S. stamp printed using the Giori Press, which allowed for simultaneous application of two or three differently colored inks, and hence only one plate number was needed in each corner of the sheet, rather than separate numbers for each color. This was also the case for the Project Mercury stamp.

Lower left pane of U.S. Scott #1107. Note the plate number in the lower left corner, and the corresponding outlined plate block.

A plate block separated from the pane, with the same plate block number, is shown below.

Lower left plate block of U.S. Scott #1107.

These four plate blocks with the same plate number could have come from the four different panes from one sheet. These are the upper left, upper right, lower left, and lower right plate blocks, based on the positions of the plate block numbers.

Clockwise from top left: upper left, upper right, lower right, and lower left plate blocks, with the same plate block number

Another article provided by the APS Research Library was a page from the 2020 Durland Standard Plate Number Catalog, which lists the plate numbers used for the printing of each U.S. stamp. The numbers used for Scott #1107 were 25978, 25985, 25990, 25993, and 26010. It turns out I have each of those numbered blocks in my collection. Robert Rabinowitz, in an article titled "Plate block collecting is changing" (Stamp Collector magazine, Dec. 26. 1992, p. 1, 3), calls this a complete matched set. The plate blocks shown below all have the plate number in what would have been the upper left corner of the sheet, hence would be called upper left plate blocks.

Plate blocks showing the five plate numbers used for printing the U.S. IGY stamp

Krause pointed out in his 1996 article that plate block collecting lost some of its appeal in the 1970s. Costs increased, especially for complete matched sets, as the number of stamps in a block was sometimes greater than four, face values of stamps increased, and more stamps were issued every year.

More on stamp production and printing, and maintaining a stamp collection, in future posts.