Question About 3271B

I have a PNC5 that was sold as 3271b (the tagging error) and I need to confirm that it is, in fact, 3271b. I have a few questions:

1) 3271 is designated "small date", 3271a is designated "large date" which size date is 3271b?

2) I assume the "tagging error" is that the stamp was tagged when it was not supposed to be. Am I correct?

3) I have no UV equipment for checking tagging, and I notice some is quite pricey. Will a standard UV bulb show up tagging? What should I be looking for to verify that the stamp is tagged?

My 3271b pair is the small date variety. It is brightly tagged. Unfortunately, I do not know if every 3271b has the small date. As far as I know, a UV lamp is the only means to verify whether the stamp is tagged. Do you know any other collectors in your locale, hopefully one with a UV lamp?
Added: According to Scott, 2971b only occurs with plate # 11111. All 2971a have plate # 33333. So all 2971b should be small date!
2971 can have plate # 11111 or 22222 ... but apparently the tagged stamps only occur with 11111.

1) It has the small date.

2) Correct

3) You need a shortwave UV light source. I don't know exactly what you mean by a standard UV buld, but if it is a "black light" I suspect it won't work for US tagging.

Thanks for both responses; that cleared up a lot for me.

Eyeonwall: I did mean a black light, and I would have to buy one of those, so I guess its time to spend a little more and get a short-wave UV light. I never bothered to get one before because I didn't intend to separate tagged from untagged stamps. But since this stamp was an "error", I thought I might as well display it with the other PNC5 varieties of the eagle/shield design.

JLLebbert: You mentioned your stamp is "brightly tagged". Does the entire stamp or only part of it glow under UV light? Does it appear as a certain color? Obviously, I've never seen tagging under UV light before. I've turned this strip every which way under normal lighting and magnification trying to pick up some surface anomaly, but no luck. BTW, my copy does have the 11111 plate number and the small date. I'm glad I have a set of dial calipers to measure these small design size variations. My tired old eyes just cannot distinguish between 1.25mm and 1.75mm with a metric rule. Both date sizes side-by-side would be easier to see, but when you don't have the other stamp...!

US tagged stamps, under short UV, glow one of three colors. Early airmail stamps (pre 1980) glow a red orange. Later airmails & most others glow a yellowish green. There are a few that glow a bluish green. The type of tagging determines how much of the stamp is covered. Block tagging generally covers a rectangular section of the stamp, leaving the perimeter untagged. Under short UV, the untagged area usually appears purplish. Note that the purple is due to the presence of tagging ... completely untagged stamps will not display the purple color.
Overall tagging (as well as solid & mottled) covers the entire stamp. Overall tagging is applied over the entire stamp after the stamp design has been printed & can partially obscure the design when it is viewed under a UV lamp. Solid & mottled tagging refers generally to the use of prephosphored paper ... the paper is treated with taggant prior to the printing of the stamp design. Whether the tagging is solid or mottled (splotchy) depends upon the paper itself. The design on such stamps tends to be clearer under UV than on overall or block tagged stamps.
A few modern US appear to glow white under short UV. It is my understanding that this is due to the paper being used rather than to a chemical taggant.
And the brief answer to your question is that the entire PNC (excepting the backing paper) should, under short UV, glow a yellowish green.

Shortwave light (about 250nm) is good for checking tagging on stamps.

Longwave light (at 375nm or so) is common for looking at minerals. Not good for tagging.


-IBFS

Thanks again JLLebbert. That's a good education on tagging. In addition to helping me now, it will serve as a future reference I'm sure.

The taggant glows yellow green. The ones that appear bluish-white have a hi-brite component that overpowers the yellow green

Thanks! I was not aware of that.

The right side of the date (8) is directly in line with the left side of the S in USA on the large date. If you have a 33333 plate number it is definitely a large date.