UV activity investigation

This sort of thing interests me greatly: a situation where some notes have UV and some don't. So I had a little look…

I got 22 UNC notes and tested them under UVA (365nm) and UVC (254nm). Here's what I found:

Most of the notes have UV activity on the reverse, but in many cases this activity is not obvious under UVA (365nm). When you switch to UVC (254nm), the UV activity is then more obvious. In this case I mean UV activity where it is in the design, or ink. Not the UV fibres.

Most of the notes have green and red UV fibres in the paper, with the green fibres being more numerous usually.

Two of my notes have no UV fibres at all, and one note has a single red fibre visible on the obverse only.

One note out of the 22 shows no UV activity at all, not under 365nm or 254nm. However if you look at the note on the reverse, the ink in the region where you expect fluorescence is a different colour so it may well be that this note was intended to fluoresce but now it doesn't for some reason.

So in general I would summarize it like this:

1) These notes all fluoresce under UV, but it may require a UVC lamp to notice it

2) Some paper sheets had such sparse UV fibre distribution that a particular note may have no UV fibres at all

I need to get more notes to work out whether there is a correlation between these findings and certain batches of notes.

If you have any of these notes with different prefixes, I would appreciate it if you post here what you have found, with UVA vs UVC and with the UV fibres.

Note when counting fibres, it is sometimes the case where the same fibre is counted on both sides of the note. That is fine, it is not supposed to be super accurate, just an indication of whether the greens or reds were sparse on the obverse or reverse.

Below are photos of four of my notes.

First, a note that has obvious UV activity under 365nm and 254nm on the reverse. The left image is 365nm and the right one is 254nm:

The next one has very faint UV activity under 365nm and obvious UV activity at 254nm on the reverse. The left image is 365nm and the right one is 254nm:

The next one has very faint UV activity under 365nm and faint UV activity at 254nm on the reverse. The left image is 365nm and the right one is 254nm:

The last one has no obvious UV at 365nm or 254nm. The left image is 365nm and the right one is 254nm:

When you look at the above note on the reverse, the ink in the circled areas is a lighter colour. In my opinion, these areas were intended to fluoresce under UV but they don't anymore, or there was an issue with the UV ink for this batch:

Very interesting research.

When I was in Malaysia earlier this year, I met a dealer and the president of one of the big numismatic associations there. He told me and showed me some examples of UV activity on Malaysia notes. Malaysia apparently has many varieties of UV activity on their notes. This gentleman explained that when they do plate changes and other types of changes, they do mark certain notes with different UV activity. When you are done with Russian notes, maybe you can start playing around with Malaysian notes.

I would need a pointer or indication where to look.

For example with these 100 Rouble notes, I saw on Numista the comment “some notes have UV” on the 1993 version. Luckily for me I could get those notes relatively easily.

The notes have to be UNC and not too expensive, because I end up having to buy all the notes I am testing.

Another note acquired, serial number Kв 3842475. It has obvious UV activity under 365nm and 254nm on the reverse. The left image is 365nm and the right one is 254nm:

Another note acquired, serial number CЯ 5482354. It has obvious UV activity under 365nm and 254nm on the reverse. The left image is 365nm and the right one is 254nm: