Collecting flat plate printed plate blocks can be a little confusing. To understand why, you have to know a little bit about the different printing processes. Letís start with stamps produced by rotary plate printing presses which are the ones most collectors are familiar with.
With rotary printed stamps, the plate numbers appear in the upper right (UR), lower right (LR), upper left (UL) or lower left (LL) corner. There are 4 stamps in a plate block. Other than the position of the plate number, the plate blocks look the same.
In the 1970s and 1980s, the USPS printed multiple plate numbers per pane. Collectors switched to collecting plate number strips. Depending on how many plate numbers were printed, strips of 6, 8, and up to a full strip of 20 are considered standard plate blocks for these issues. Plate numbers appear on either the top or bottom of the panes. Or they appear on the left or right sides of the pane.
With the modern issues (post 1935), collectors expect typical size margins regardless of the position. Under normal circumstances, margin sizes donít vary more than a millimeter or two. The process of cutting sheets of stamps into individual panes is very uniform.
Gum covers the entire pane of stamps, or at least extends well into the margins and is evenly applied to the pane.
Those are the characteristics of modern plate blocks that most collectors are familiar with. Letís see how flat plate printed stamps differ.
Flat plate printed plate blocks usually have a plate number opposite the center stamp in a block of six stamps. A few issues require more stamps to make up a plate block. For example, the Norse-American issues (Scott #620 and #621) are collected as a plate block of eight.
The margins on these flat plate printed stamps can vary greatly. The gumming also varies. Why?
Many flat plate printed plate blocks have plate numbers on all 4 sides of the stamps: top (T), bottom (B), left (L), or right (R) are common designations. In general, prices for top or bottom plate blocks are a little higher than left or right plate blocks. Thatís because many collectors prefer a top or bottom plate block because thatís what is depicted in printed albums.
In these early days, no one was concerned about the margins. Sometimes the panes were cut apart with very wide margins. Sometimes they are very short. There is no right or wrong way here. Itís just the way it was done. Differences of an inch or more in size are not uncommon.
Printed albums have spaces for these plate blocks and they leave enough room for the average size margin. But when collectors get copies that are wider or narrower, they think there is a problem. There isnít.
Yes, your plate block may be larger in size than the space in the printed album. Itís OK. Itís supposed to be that way. Likewise, a plate block with a short margin doesnít necessarily mean that the margin was cut down or reduced. In a printed album, these plate blocks donít take up the entire space. Again, itís OK.
Some collectors prefer plate blocks with average or larger than average margins. And they will sometimes pay a little extra for that ďfull marginĒ appearance. Part of it is probably aesthetics. Part of it is filling up the album page so it doesnít look so bare.
Sometimes the outer edge of the margin can become damaged due to mishandling. It is possible to reduce the margin slightly to remove the flaw. Because margins arenít a standard size, it takes very careful evaluation to determine if a margin has been altered or not. Sometimes itís impossible to tell.
Gum is another factor. No one cared about perfect gum. As long as it covered most of the stamp, it was allowed to pass. Depending on how the gum was applied, it may extend into the margin only a tiny bit. Sometimes, the gum wasnít applied evenly and there are gum skips on the stamps themselves. This affects the value of the plate block. Gum skips in the margin area only are normal and they donít affect the value of the plate block.
When you collect the older flat plated printed stamps, just remember that things arenít going to be as consistent and orderly as the modern issues. There will be variances in margin size and gumming. Most of these variances are quite normal and donít affect the value of the plate block.