As I stated almost three weeks ago, I've done some tests on the so-called HOW "test notes". I took some infrared spectra fron a HOW "test" (0,84 M range), a regular HOW (1,10 M), a australian polymer note (made of Guardian polymer) and a Isle de Man Bradvek-made note.
I easily identified that the Bradvek note is polyethylene (as it supposed to be) andthat the Guardian note is polypropylene (which is also correctly found). I took the measurements on blanks areas, since the inked ones shows distinctive bands of absorption.
When I took the spectra on both HOW notes, also on blank areas, I found NO DiFFERENCE at all. Both are truly made of paper and I found no traces of any polymer on the HOW 0,84 M.
So, all I can say for sure is that these notes doesn't contain any polymer in the paper.
But I cannot rule out that they are made with a new paper composition (I cannot tell which one because I'm not a specialist of paper).
However, I presented to the technician both notes (he doesn't know anything about paper money and he closed his eyes for the test) and by touching both notes, he easily found the "test" note, telling me that the "test" was thinner than the other. Since the weight is almost identical (we verifyied it on an analytical digital scale) to about 1 mg, the "test" paper must be more dense than the normal one.
I also examined both notes under magnification with a stereomicroscope but I didn't saw anything different (The maximum enlargment I used was 70X). Maybe under a electronic microscope, we can see a difference, but I don't have this equipment.
I cannot draw a definitive conclusion, but I'm not helpless since I know somebody in a research center specialized in pulp and paper. Maybe he could do some very specific tests to see if the paper composition is different. I will try to contact him in the next few days to see if he can do these tests...