Plate block collecting used to be popular among philatelists who wanted to obtain a copy of each major printing of a stamp produced in a long running definitive series. Obtaining the corner block, or centre block containing the plate number and inscription "proved" that the stamp came from a different printing. Also, since records were generally kept of when the different plates were put to press, a specialist could assign different printings to a specific date. It used to be extremely popular among collectors in the 1950's and 1960's. On Canadian sheets, the layout of a printing sheet was usually between 200 to 600 subjects arranged into 4 or 6 smaller sheets for distribution to the post offices. Usually, the inscriptions were placed on the outer corners of the larger sheets. This meant that for any given post office sheet, you would only get one corner. If you collected all four corners of a plate, they could be arranged on an album page to resemble a miniature sheet of 16 stamps.Many collectors found this very appealing and would often visit many post offices when a stamp issue came out to obtain all four corners of a plate.
Many postal clerks found this to be an extreme nuisance, so in 1957 and 1958, the post office department went to extraordinary lengths to effectively discourage the practice by having all the sheets trimmed to remove inscriptions. However, a public outcry caused the post office to reverse its position in late 1958, and gave rise to what we know today as the philatelic-field stock distinction. From this point on, philatelic panes had the blocks left intact, while field stock panes had the inscriptions removed. The bulk of stamps printed in recent years have been field stock of course, so there are now many printing varieties that only exist on field stock.
However, once the use of multiple plates to print an issue ceased, and photogravure and lithography supplanted engraving as the preferred method of stamp printing, the significance of collecting plate blocks changed, although it remained the same for the definitives. Because of this decreased significance and the subsequent rise in postage rates, the popularity of collecting plate blocks has fallen in recent years.
However, it is still the only way the place the various shades, and papers in the correct order. Then once this is accomplished, a parallel study of cancellations on used stamps will enable a specialist to accurately date specific shades, paper and gum types.
Defining the Scope of A Specialized Collection
So far we know that:
1. There were up to 22 different shades of some values in this set.
2. There are up to four different gum types.
3. There are up to four different arrangements of position dots on two positions in each plate.
4. There are up to five different paper textures.
5. There are up to a different dull fluorescent papers and three or four fluorescent papers.
6. There are three different intensities of taggant on the Winnipeg tagged stamps.
Now, not all of these varieties will exist with every other variety, so the number of variants is not purely multiplicative. However, the existence of the above variations expands the potential scope of this issue considerably.
Here is an example of how I would classify and arrange such a collection. Here I assume a certain number of shades for each value and papers on which each shade can exist:
Part 1: The Horizontal Wove Papers
1c violet brown - plates 1-9: 10 sets including 9n: ((10 x 4)x4x2) = at least 320 varieties.
2c green - plates 1-9: 12 sets including 7n, 8n, 9n: ((12 x 4) x 3 x 4) = at least 576 varieties.
3c carmine rose - plates 1-2: 2 sets ((2 x 4) x 3 x 7) = as many as 168 varieties.
4c violet - plates 1-12n: 14 sets including 10n, 12n: ((14 x 4) x 10 x 4) = as many 2,240 varieties.
5c blue - plates 1-12: 12 sets: ((12 x 4) x 9 x 4) = as many as 1,728 varieties.
6c orange - plates 1-2: 2 sets ((2 x 4) x 4) = as many as 32 varieties.
10c violet brown - plates 1-5 ((5 x 4) x 4 x 3) = as many as 240 varieties
15c black - plates 1-3: 4 sets ((4 x 4) x 4) = as many as 64 varieties
20c green - plates 1-3: 4 sets ((4 x 4) x 4 x 2) as many as 128 varieties.
25c vermilion - plates 1-2: 2 sets ((2 x 4) x 4 x 3) = as many as 96 varieties.
Part 2: The Vertical Wove Papers
1c violet brown - plates 11-12: 2 sets ((2 x 4)x12x4) = at least 384 varieties.
2c green - plates 11-20: 10 sets ((10 x 4) x 12 x 2) = as many as 960 varieties.
4c violet - plates 13-19: 7 sets ((7 x 4) x 9 x 12) = as many as 3,024 varieties.
5c blue - plates 13-19: 7 sets ((7 x 4) x 12 x 12) = as many as 4,032 varieties.
15c black - plate 4: 1 set ((1 x 4) x 9) = as many as 36 varieties.
20c green - plate 4: 1 set ((1 x 4) x 4 x 2) = as many as 32 varieties.
Part 3: The Tagged Stamps
1c violet brown: (1 x 4 x 12 x 4 x 3) = as many as 576 varieties.
2c green (1 x 4 x 12 x 2 x 3 = as many as 288 varieties.
3c carmine rose ( 3 x 4 x 12 x 2 x 3) = as many as 864 varieties
4c violet (1 x 4 x 9 x 12 x 3) = as many as 1,296 varieties.
5c blue (1 x 4 x 9 x 12 x 3) = as many as 1,296 varieties.
This ignores the official stamps completely. Further, I do not know if every paper type exists in every shade, but if the number of varieties is this large then it means that there are over 18,380 possible different plate blocks to collect in this issue in order to obtain every combination of paper and shade that could exist with each plate. If you are able to buy these for $1 per block, which is very optimistic, you are still talking about spending over $18,000 on this issue.
All of the sudden, when you look at it this way, this issue does not have to be any easier to complete than you want it to be. Remember that we haven't considered coils, booklets, proofs or postal history yet, not to mention errors. Thus I would contend that you can easily spend a lifetime collecting this issue and spend tens of thousands and still not be done.
The nice thing though about this issue is that it is actually possible to do this because the pool of available extant material is large enough. You could never hope to do this with the classic period even if money was no object. Why? because the material just doesn't exist on this scale for the classic period. However, if we keep using this material for postage, there will come a time when this too will be impossible, and that would be a shame for philately I think.