Canada Tagging Help

I'm working through the Canadian "Landscape" series of definitives from the 1970s and still having problems with tagging. I understand that tagging on used stamps can be difficult with migration, washing off etc. I have mostly stamps with distinct yellow tagging which I assume is OP2. I have found none that show tagging that obviously has faded or migrated. And there is a small number that appear to be tagged, showing faint clear bands over the perfs. These faint lines look like the tagging on some of my cameo series stamps (but a little fainter) where there was no OP4 (migrating) tagging so I wondered if it was Wpg tagging on the landscape stamps. It is so faint that I can't pick up any afterglow under fluorescent light. There are some anomalies. I have a 25 cent horizontal strip of three with only these faint tagging bars, but they are 8 mm wide over the perfs. In this case at least, the faint lines appear to be under the ink. I have a 50 cent with the same faint tagging (more normal width) but Unitrade says there is no Winnipeg tagging in this issue. Under magnification in normal light they appear to be finely cross-hatched. I'm confused. Do Winnipeg and OP4 and OP2 start out looking the same? Does Wpg tagging fade, or migrate? If OP4 migrates, does it leave these faint lines behind? If OP2 does not migrate, does it fade? Unitrade gives widths of 3 and 4 mm for OP2 tagging; how wide is Wpg and OP4 tagging? I did consider that maybe these were untagged, but there are too many for me to be that lucky, and in any case untagged is not reported in the 25 cent.

Winnipeg tagging doesn't migrate, nor does OP2. OP4 is the bad guy here, the others are OK. Winnipeg tagging is noted for fading somewhat during soaking. OP2 is completely stable in that regard, you can soak it overnight and nothing will happen to the tagging. I don't know what causes the taggant to look so different on some of the Landscape definitives - perhaps it's some sort of reaction over time to atmospheric conditions, perhaps the taggant looked different right off the bat due to fiddling with its chemical makeup. I've seen some tagged stamps that are only available with OP4 (such as the 1972 Health Day issue) that have tagging that looks exactly the same as the colour seen with OP2 tagging (with the exception of a bunch of migration of the tag on those OP4 stamps). I've seen other OP4 stamps that are very pale under UV light, as you describe.

Winnipeg (phosphorescent) tagging is not at all the same as the OP2 / OP4 (fluorescent) tagging. Winnipeg tagging was intended to work based on the residual afterglow once the UV light is turned off (or, more likely, once the stamp is moved out of the UV light - I'm sure the automated equipment would leave the light on and just pass the letter through the UV source). You can see phosphor tagging a bit while the lamp in on, but it's most noticeable in a darkened room immediately after you turn off the UV light. OP2 / OP4 is scanned while it is in the UV light source - there is virtually no afterglow once the UV light is turned off, at least none that can be useful for any type of automation.

Winnipeg tagging bars on the Landscape issue are much wider than the 3 to 4 mm used for OP2 / OP4. I suspect that excessively narrow bars are not practical for Winnipeg tagging, as they probably wouldn't generate enough phosphorescence to guarantee that the scanning would work properly.

The cross-hatching you see on the tagged areas might just be due to the printing process used to apply the taggant. For Machin collectors, the tagging can be identified by the screen mesh used when printing the phosphor bars - some Machin stamps come with the phosphor bars printed with a screen that was 150 dots per inch, some are 250 dots per inch.

Robin Harris (the Unitrade catalogue editor) has a good page on his Adminware site that shows some images of the tagging found on Landscape definitives.

http://www.adminware.ca/checklist/c...d_medium.htm

Ryan

edit: in case you don't spot the link in the page above, the same info on tagging is found in an expanded version on this "Tagging Study Tips" page.

http://www.adminware.ca/checklist/chk_tag.htm

Thanks again Ryan for excellent information. I did edit my draft to acknowledge your earlier advice about seeing the afterglow on Wpg tagging, and also to say I had looked at the Adminware site, and that I have no landscape stamps that look anything like the OP4 example he shows. Somehow my edits vanished when I submitted the post - I'll learn the system yet. I'll look at stamps again with your comments in mind. One more question - could badly faded Wpg tagging look like badly faded OP4 tagging? I may also try to get a decent photo of what I am seeing and post it.

Not to my eyes, no. Phosphorescent Winnipeg tagging is basically light blue in oolour when viewed under the UV lamp. OP4 is basically greenish yellow, fading all the way to a sort of straw colour when it's really faint. Of course, the more they're faded, the more the glow of the paper comes out rather than the glow of the tagging. But I don't have my eyes open with the UV lamp on when I'm looking for stamps with Winnipeg tagging. I close my eyes with the room dark and the UV lamp on, and I don't open my eyes until I turn the lamp off. There's no way to mix the OP2 / OP4 stamps up with Winnipeg tagged stamps then, since the fluorescent tag has no afterglow. If it's still glowing after you turn off the lamp, then it must be phosphorescent Winnipeg tagging.

Ryan