Ottawa Tagging on The 1967-1973 Centennial Issue

None of the Ottawa tagging exhibits any afterglow. The glow under UV is very bright while the UV light source is shone directly on it, but when the lamp is switched off, any visible glow abruptly disappears. 

Initially when Ottawa tagging was first introduced, the taggant compound used had the trade name OP-4. This taggant compound was found to be unstable, and migrated from the stamps onto other stamps and any substrate with which they came into contact. Because of this, a new compound was introduced almost immediately, with the name OP-2. This later compound was chemically stable and has been in use ever since. 

The above picture shows two 25c booklets, each with the two different types of tagging. The OP-4 type is shown on the right. Generally, the OP-4 is recognizable by the colour, which although it does vary, it always has a pale, faded appearance, due to the migration that has taken place over the years. In contrast, the OP-2 tagging always appears deeper and brighter, as shown by the booklet on the left. 

The migration of the tagging can best be seen by examining the back of affected stamps under a UV lamp. Depending on how severe the migration is, the back will have an uneven fluorescence, with an apparent diffusion of the tagging throughout the back. I don't have an example of this on this issue that shows up well in a picture. However, I do have several blocks and pairs from the next issue, the 1972-77 Caricature issue, that show the appearance of this migration very well:

The block on the left is only very mildly affected, and the migration is really only apparent within about 3 mm on ether side of each row of perforations. In contrast, the migration is so severe in the right pair, that the fluorescence of the paper has been completely distorted by the taggant compound. 

The Unitrade catalogue asserts that such stamps are damaged. I do not agree entirely with this assessment, as the vast majority of OP-4 tagged stamps are affected in this way to a more or lesser extent. I think that from the perspective of collecting and studying the paper varieties, that yes, such examples are not desirable because the reading of the fluorescence is not a "true" reading. However, for collectors who are simply seeking a collectible, basic example of the OP-4 stamps, I think that provided they are sound in all other respects, they are perfectly good stamps. 

The OP-4 tagging only seems to be found on some of the booklet stamps that were printed by the BABN, being the 1c, 6c, and 8c. None of the CBN stamps have been found thus, nor have the other stamps printed by the BABN been found with this type of tagging. 

The booklet pane shown on the left is the OP-2 tagging, which is easiest to spot by the depth of the colour. OP-2 tagging appears both bright and solid, and not washed out. 

The colour of the tagging bars for both OP-2 and OP-4 tagging exhibits some variation under the UV light. The colour varies from pale greenish yellow, to pale green, to deep yellow, to an orangy yellow. 

All of the OP-4 tagging that I have seen on this issue appears either pale green or pale greenish yellow, as shown in the pictures below:

This picture shows a 1c booklet stamp with 4 mm OP-4 tagging on the top row, and a pair from a booklet, with 3 mm OP-2 tagging on the bottom row. In this example, the OP-4 tagging appears pale green. 

Here is a block of 4 of the 1c, this time from the $1 booklet that was issued in 1972. In this instance, the tagging appears slightly more yellowish, being a bright greenish yellow. 

Here is an example of a 1c booklet stamp with 3 mm OP-4 tagging that appears a pale yellow. 

OP-2 tagging in contrast to the OP-4 tagging appears either a bright yellow, a very bright greenish yellow, or a bright orangy yellow on this issue. It tends not to appear green, but more yellowish. 

In this picture, the bottom 1c pair which comes from one of the 25c BABN booklets is tagged with 3 mm OP-2 tagging. The tagging glows a bright yellow under the UV light. 

In this example, the booklet on the left has the OP-2 tagging, which is 3 mm wide, and glows a light, bright greenish yellow. 

Here, we have a block of the 6c black CBN sheet stamp, with 4 mm OP-2 tagging, that glows a very bright greenish yellow. Although there is a clear greenish tone to the yellow, there is much more yellow than green to the colour. This is the colour of most Ottawa tagging that is found on most stamp issues, even today. 

Finally, here is an example of one of the CBN high values, with the 4 mm OP-2 tagging. In this case, there is less green in the yellow, to the point that this is more a pale, bright yellow. 

Like the Winnipeg tagging, the appearance of the tagging on the stamps varies in normal light, from light tagging, that is barely visible to the naked eye, to dark yellow bars that are impossible to miss. 

Here is a block of the 1c reddish brown with PVA gum, that is tagged with 4 mm OP-2 tagging. As you can see, the bars are just barely visible, and could easily be overlooked if you weren't looking for them. 

The above picture shows a 2c green on ribbed paper, with PVA gum that is tagged with 3 mm OP-2 tagging, that is moderate in its intensity. The bars appear a light yellow in normal light, and although they are clearly visible, are by no means dark. 

Here we have a corner block of the 4c bright carmine with PVA gum and 3.25 mm OP-2 tagging. In this case, the tagging bars appear a dark yellow, and it is impossible not to notice them. 

Here is an example of the 10c Jack Pine with PVA gum that has dark 4 mm OP-2 tagging. 

The OP-4 tagging is found in two different widths: 3 mm and 4 mm. Both appear to have been in use concurrently, as they first appear on the 25c booklets, which were printed by BABN, and first issued on December 30, 1971. 

The booklet pane on the left is tagged with 4 mm OP-4 tagging. 

The above 1c booklet stamp is tagged with 3 mm OP-4 tagging.

Measuring the width of the tagging is easy on multiples where you have a full tagging bar. But on single stamps, it becomes more difficult. One way to identify the type positively is to measure the space between the bands. 4 mm tagging will have a gap of 20 mm between the bars, whereas the 3 mm tagging will have a 21 mm gap. This is a sure-fire test. However, it is also time consuming because of how long it takes to measure the space between tag bars. A good, quick visual test is to look at the degree to which the bars occupy the margins and overlap into the stamp design. With a 4 mm band, you will generally see a considerable amount of overlap into the design on one of the two sides. With the 3 mm tagging, you will usually see the tagging take up the margins on both sides, but not overlap into the design that much. If, you do see overlap on one side, it will be offset by almost no tagging being visible on the opposing side. Look at the above pictures again, and you will see what I mean. 

It was taken for granted for the longest time, that all the OP-2 stamps had 4 mm tagging. However, that is not the case. In addition to 4 mm OP-2 tagging, I have seen 3 mm OP-2 on some of the booklet stamps, as well as 3.25 mm OP-2 tagging on some of the CBN sheet stamps. 

Here is an example of the 1c with 4 mm OP-2 tagging. I have found that the 1c, 3c precancel, and some printings of the 6c black CBN stamps have 4 mm tagging. 

Here is an example of the 15c Bylot Island with 4 mm OP-2 tagging. All of the high values printed by CBN, that exist with Ottawa tagging, being the 10c, 15c, and 20c are generally found with 4 mm tagging. 

Finally, the 4c bright carmine, shown above, has what at first appears to be 3 mm tagging. I measured the tagging on this block and found that it is in fact not 3 mm exactly, but 3.25 mm. I have seen this tagging on some printings of the 4c, and the 2c. 

As was the case with the Winnipeg tagging, all the known forms of Ottawa tagging exist with severe horizontal shifts, resulting in apparent one bar tagging errors. Unfortunately, I do not currently have an example of such an error to show. However, I do have an example of a 1c with 4 mm Op-2 tagging, that is shifted so far to the left, that the left tag bar is almost completely missing, touching just the perforations at the edge:

The spacing between the tagging bars varies, depending on whether the stamp was printed by the BABN or CBN, whether it is a low value or a high value, and what the width of the tagging bars are. The spacings that I have found in my examination of the stamps of this issue are as follows:

• 3 mm OP-2 and OP-4 - BABN  stamps and 6c black CBN sheet stamp:  21 mm
• 4 mm OP-4 booklet stamps and 6c black CBN sheet stamp with 4 mm OP-2: 20 mm
• 3.25 mm OP-2 CBN sheet stamps: 22.5 mm
• 4 mm OP-2 high value CBN stamps:  28 mm

In the case of Winnipeg tagging, the bars were seen to be printed continuously across the sheets in a horizontal direction, but not continuously in the vertical direction, requiring more than one application to tag all 600 stamps in the full sheets. However, it appears that the Ottawa tagging was applied continuously in both the horizontal and vertical directions:

• The spacing between the tagging bars is the same, no matter which position on the sheets we are looking at, and no matter which pane is being examined. 
• The tagging bars generally extend the full length of the selvage in a block, except for blocks located in the bottom panes. On those blocks, the tagging stops just short of the bottom of the selvage. However, there is no evidence of any "next series of bands" that we often see on the Winnipeg tagged blocks from the centre panes. Generally, any block coming from one of the centre panes will show tagging that extends the entire length of the selvage.

Here is an example of a lower left block that comes from one of the bottom panes. Because the width of the selvage is the same on both sides, it is reasonable to conclude that this block comes from the lower left pane, as there would be no need for the tagging bars to extend all the way to the bottom. 

In contrast, this block of the 4c bright carmine shows tagging that extends all the way through the selvage at the top. This suggests that the block comes from one of  the lower panes. In this case, the selvage tab at the left is wider than the one on top. That suggests that the left edge is one of the outer sheets, but the top edge is shared with an adjacent sheet. Thus the only logical position for this block is the upper left position of the lower left pane. 

This concludes my discussion of the Ottawa tagging on this issue. Next week's post will be a shorter one discussing the perforations found on the issue, and then in the two weeks following next week, I will look at the plate characteristics, starting with the die type differences on the 6c, and the plate flaws found on the other values.