Paper Fluorescence Levels On 550p: Help?

I've been looking at these 3 stamps for a few hours now, comparing them to the reference stamps from the
Elizabethan-era Definitives Fluorescence page and I honestly can't figure it out. I'm getting the impression that either the process of figuring out whether a stamp has DF or NF or MF paper is either a whole lot harder than it looks or is more of an art than a science or (most likely) I'm making a rookie mistake and missing something obvious. Either way, I definitely need some help.



I can definitely see fluorescent fibres on the middle stamp, and the only variety I've found for 550p that has those is 550pvi (LF/fl). If that's right, the brighter bottom stamp is either 550piv (MF) or 550pii (HF), and the duller upper stamp is either 550p (LF) or 550pv (DF).

But trying to compare them to the reference stamps is where I'm getting lost. Putting the brighter stamp next to the MF and HF references doesn't seem to match either of them - or it seems to match both of them. I've been staring at them long enough to convince myself of either case.

Can anyone give me some pointers on this? Hibrite paper vs anything else I figured out easily. But even with the reference stamps I feel like I'm just spinning my wheels on the other paper fluorescence levels. It can't really be this hard, can it? What am I missing?

I am not familiar with Canada, but I work on fluorescence in Latin American stamps. My impression is that your top stamp may be phosphorescent rather than fluorescent. Fluorescent stamps have a bluish-white response to UV, but phosphorescent stamps respond with a change in color, usually yellow but sometimes yellow-green or blue (other colors probably exist). The bottom two stamps appear to be fluorescent, but obviously are not uniformly so. Fluorescence and phophorescence may involve the entire stamp uniformly, or may appear in patterns which is what you seem to have here with the vertical bars. For that reason, I would be hesitant to assign a single intensity value to the bottom stamp--it has two values.

Silverlock. You should read the introduction in the Unitrade catalogue where there is a section (page 25) dedicated to Paper Fluorescence.

GJP

I guess I'll have to save up and buy an up to date copy. Thank you for your kind help.