How to handle phosphor tagged issues question

Your original question about "phosphor" tagging might lead you in the wrong direction.  Phosphor is the glow-in-the-dark Winnipeg tagging, started here in 1962 and still used in the UK today.  That stuff glows under UV light a little bit, but it works best immediately after you turn the light off - it keeps glowing for a little while and that's how the detection equipment works (from what I understand, it flashes short bursts of UV light at the stamp and reads the returned glow when the light is off).  Ottawa tagging is what has been in use since 1972 and it only glows when the UV light is on - that is fluorescence (glow-in-the-dark is phosphorescence).  Your Wildings / Cameos / old Centennials with Winnipeg tagging won't be at any risk of migrating tagging, that type isn't the problem.

There are two main types of Ottawa tagging, OP-2 (what's in use today) and OP-4, which was the initial formulation that caused all the problems.  OP-4 migrates through paper (glassine is a kind of paper, so it can't solve the migration problem).  They figured out the problem relatively quickly, but even a small amount can turn into a large problem.  I don't think OP-4 will migrate through plastic / Mylar, but it would probably contaminate the inside of a mount if you were to try to re-use it later.  I suppose on a split-back mount it might even migrate through the gap into the album paper.

I've seen big differences under UV light of various OP-4 tagged stamps.  I wonder if there are storage conditions that make the problem worse (for example, maybe damp & cold makes it worse, or maybe hot & dry makes it worse) - no idea, but there is a lot of variance.  Some of the stamps I've seen have been horribly contaminated, big ugly fluorescent glow on the back of the stamp, whereas others hardly migrated at all.  I've also seen different colours of fluorescence.  Maybe there were various different OP-4 formulations as they tried to solve the problem.

OK, more snooping and I found another post I made back in the day, including a couple of photos I had taken under UV light.  The shots of the back of the stamps clearly show the problem.  Note that you would never be able to spot this problem without a UV light.  So, if you don't care about UV lights, maybe you won't care about migrating taggant either!

-----

Fluorescent tagging will glow only when the UV light is shining on it - as soon as the UV light is turned off, the tag stops glowing. Phosphorescent (Winnipeg) tagging has an afterglow that lasts a few seconds, and it's most easily seen in a completely darkened room. I have a guest bathroom that has no windows and that has become my UV room (I don't have any guests but I have a lot of tagged stamps!). Turn off the lights and shut the door and it's almost completely dark inside, and it's easy to spot phosphorescent tagging that way. I run the light over the stamps with my eyes closed, and then I turn off the lamp and open my eyes - the stamps with Winnipeg tagging jump out at me then.

Winnipeg tagging is somewhat susceptible to soaking - used stamps are often more difficult to identify than mint ones. I find this to especially be the case with British stamps, which use the same type of phosphorescent tagging method as the Winnipeg tagged stamps. OP2 tagging doesn't seem to care how long you soak it, it stays bright under UV light.

I'm sure there are storage considerations for all types of tagging, but I'm also sure there are unequal amounts of phosphorescent / fluorescent material in tagging. Some mint stamps can have extremely bright tagging whereas others are much less vivid.

OP4 tagging, the migrating stuff, is a bit odd in that it doesn't seem to be the same from one issue to another. Some of the high value Landscape definitives (like the 25c polar bears) from the early '70s have very faint OP4 tagging. Some stamps, like the 1972 8c World Health Day commemorative, can have very bright tagging. Colour can vary somewhat, and I don't yet have a good sense of what kind of tagging is what, because sometimes the OP4 can look almost exactly like the OP2.

The Health Day stamp is a good issue to look at (on mint stamps especially) when trying to understand the possible problems - you can often see tagging "soaking through" to the back of the stamp. Here's a photo of a horrible example, some OP4 stamps I got once in a glassine - everything glows to some degree, the front of the stamps, the back of the stamps (I've turned a couple over), the glassine envelope, probably the spot on the table where I've set the envelope ....

The stamps turned over are the Health Day stamps, and you can see the design of the 1972 Frontenac stamps (also with migrating OP4 tagging), which look pretty much the same on the back side. I've also attached a shot of a couple of different Health Day stamps turned over, which obviously show different levels of problems with tagging migration.

 

Ryan

Great Post Ryan! Very informative.

No great secret to that, I hold the UV light with one hand and the camera with the other.  I have a UV light that's on the bigger side of things, one of the metal Raytech things with two different wavelengths.  If I turn on both wavelengths and hold it close to the stamps, it makes quite a bit of light.  The other part of the equation is to have a room that's as dark as possible.  Not a problem for me at any time of day with my room with no windows, all I have to do is shut the door and stick a towel over the gap at the bottom, and I have a pitch black room.  Lots of light from the UV lamp and no light otherwise and the pictures come out fine, even with a miserable little point & shoot digital camera.  If I fussed with exposure and aperture and who knows what else, I could do much better, I'm sure.

Ryan