Unusual UV activity

Hello everyone,

I've come across this Czech 100 Kč note which has UV activity different from standard notes. There's an extensive blue area in the lower part of the portrait on the right side of a banknote (I added normal 100 Kč note for comparison on the second picture, sorry for the worse quality of the photos). 

I know that sweat or other substances can sometimes be seen under the UV light in a similar way, but in this case the area seems much larger, brighter and also too regular to be caused just by some stain. It also happens to have really similar colour as some UV features used on 1000 Kč notes of the same printer. I also have to add that the note is circulated (around F), but its state doesn't seem to explain this. Have you seen similar notes before and do you think this could have been caused during the print?

Thanks in advance for your help and insights

According to  the official website of the CNB  the large blue area in the lower part of the portrait on the right side of a banknote is the standard. 

See: 

https://www.cnb.cz/en/banknotes-and-coins/banknotes/100-czk-uv/

redlock

According to  the official website of the CNB  the large blue area in the lower part of the portrait on the right side of a banknote is the standard. 

See: 

https://www.cnb.cz/en/banknotes-and-coins/banknotes/100-czk-uv/

Thanks for the link (I really don’t know why I haven't looked there myself🙂), but the UV activity described on the website doesn’t actually reflect how most banknotes in circulation look like. All 100 Kč banknotes I observed under the UV light in several past years only had light green fluoresnce and not the blue one (upper part of the value number and the area of right part of the portrait), regardless on the prefix. Not even UNC pieces I got directly from the ČNB cash desks had that blue fluorescence.

Furthermore, the blue fluorescence pictured on the website doesn’t correspond to the blue area on my banknote-it’s located more to the left in my case, as can be seen in the picture above (compared to the piece from the ČNB website below).

My question was also aimed in a more general way, if such errors in the UV print really can happen in printing houses and if anyone has seen such a banknote (doesn’t necessarily have to be the Czech koruna).

What wavelength is your UV light?

It might be that the blue only appears at shorter wavelength, such as this Tanzania note. Left image is 365nm, right image is 254nm:

Can you tell me what prefix that strange note has, and what the prefixes are on your other notes?

The reason I ask is because I could be persuaded to get some of these off eBay and check them.

By the way this Brazil note has a blue contaminant on it visible under UV. Nothing shows up under normal scans:

It might be that you have two problems:

1. Your light doesn't pick up the blue that is expected on a normal CZ note

2. You have one note that is contaminated under UV

As a matter of interest, see this note from 1988. Under UVC red blocks appear. Left image is UVA, right image is UVC:

odd job

Can you tell me what prefix that strange note has, and what the prefixes are on your other notes?

The reason I ask is because I could be persuaded to get some of these off eBay and check them.

 

By the way this Brazil note has a blue contaminant on it visible under UV. Nothing shows up under normal scans:

 

 

It might be that you have two problems:

 

1. Your light doesn't pick up the blue that is expected on a normal CZ note

2. You have one note that is contaminated under UV

 

As a matter of interest, see this note from 1988. Under UVC red blocks appear. Left image is UVA, right image is UVC:

 

 

 

Thanks for the reply and comparative photos. The UV lamp I use is a really simple one and doesn’t specify the exact wavelenght. It should be within the UV-A spectrum, however,  since I could always see the UV-A but never the UV-C activity on banknotes which have a UV activity under both wavelenghts (like a Hungarian 500 forint 2018).

I guess the wavelenght isn’t the problem in this case. I’ve used the same UV lamp for several years and tens of 100 Kč 2018 notes looked exatcly the same under its light regardless on a prefix. Only the one I posted has an extra blue fluorescence (which is also different from the official picture at the ČNB website, so it looks like an error). 

As for the contamination, that was exactly what I was thinking at first (I’ve already encountered some Czech banknotes which looked like your Brazilian piece). The thing is the blue area is quite large and sharp for a normal stain or contamination. Unless someone made it on the note on purpose when it was in circulation (which would explain the sharp edges, but seems quite improbable), the error seemed like the only other option to me. That’s why I wanted to ask if it really would be possible during the print. 

The note has a prefix N 79, but there‘s no need to buy them for examination. I encounter banknotes from the N series in circulation every few days (including some UNC ones), so I've already checked a lot of comparative material. Which is exactly why it puzzles me to see one different banknote when others look normal. 

But what I mean is: maybe the blue part of the “100” only shows up under UVC?

The other blue also, on the right side that is on the bank's note.

odd job

But what I mean is: maybe the blue part of the “100” only shows up under UVC?

The other blue also, on the right side that is on the bank's note.

You might be right about it of course.

But, just for the clarification, my question was not about the difference between the "official" banknote on the ČNB website and my banknotes (I only posted the image from the ČNB website as a reply to redlock). 

The question was about the difference between these two baknotes on the photo below. The upper banknote looks just like all 100 Kč pieces I found in circulation (only fibres, gothic arches and lower part of the value in green are visible under the UV-A), while the lower baknote has the anomaly I was asking about. They are both the same year and both have an N prefix. I also observed these and all other 100 Kč banknotes with the same lamp, which only emits UV-A light.

Sorry if I wasn't entirely clear about my question.

I can clear one thing up: the 2018 note has two different fluorescent appearances, under UVA vs UVC.

I acquired a 2018 today.

Under UVA (my light is 365nm):

1. The lower half of the 100 denomination on the upper left on the obverse fluoresces GREEN.

2. The upper half of the 100 denomination on the upper left on the obverse does NOT fluoresce at all.

3. There is no blue fluorescence anywhere on the obverse or reverse, except for fibres that fluoresce blue in the paper.

Under UVC (my light is 254nm):

1. The lower half of the 100 denomination on the upper left on the obverse fluoresces a dull GREEN.

2. The upper half of the 100 denomination on the upper left on the obverse fluoresces strong BLUE.

3. There is blue fluorescence on the right hand side of the obverse and this fluorescence matches the bank's image. 

4. There is no blue fluorescence anywhere on the reverse, except for fibres that fluoresce blue in the paper.

The ornamental features at the lower left and upper right on obverse and reverse will fluoresce GREEN regardless of whether you check with UVA or UVC.

odd job

I can clear one thing up: the 2018 note has two different fluorescent appearances, under UVA vs UVC.

I acquired a 2018 today.

 

Under UVA (my light is 365nm):

 

1. The lower half of the 100 denomination on the upper left on the obverse fluoresces GREEN.

2. The upper half of the 100 denomination on the upper left on the obverse does NOT fluoresce at all.

3. There is no blue fluorescence anywhere on the obverse or reverse, except for fibres that fluoresce blue in the paper.

 

Under UVC (my light is 254nm):

 

1. The lower half of the 100 denomination on the upper left on the obverse fluoresces a dull GREEN.

2. The upper half of the 100 denomination on the upper left on the obverse fluoresces strong BLUE.

3. There is blue fluorescence on the right hand side of the obverse and this fluorescence matches the bank's image. 

4. There is no blue fluorescence anywhere on the reverse, except for fibres that fluoresce blue in the paper.

 

The ornamental features at the lower left and upper right on obverse and reverse will fluoresce GREEN regardless of whether you check with UVA or UVC.

 

Thanks for checking this. I will then continue searching and asking if the note I send could be an error or if it was caused after the print.  

By the way, it's interesting that other Czech Crown denominations currently circulating apparently don't have different UV features under UV-A and UV-C. At least they all looked exactly like on the ČNB pages when I observed them with a UV-A lamp, unlike 100 Kč. This was also the case with 100 Kč from older 1997 series, I never could see fluorescent images described on the webpage, only fibres. Given that all banknotes have been printed in the same printing works in Prague for three decades, I wonder what could have caused the difference between 100 Kč and other denominations.  

Anyway, thanks for all your documentation on UV properties, it's a topic which is usually a bit neglected here on the forum.

I think you are best off getting a new UV light. 

I have here also a 1997 note, and it has obvious algae-green fluorescence on the obverse which is visible under UVA.

Under UVC that colour changes to a brighter aquamarine, not an obvious blue like the 2018 note.

I am trying to get other notes from this series, since this sort of variable interests me. Once I have done the proper photographs I will put them in the catalogue.

odd job

I think you are best off getting a new UV light. 

 

I have here also a 1997 note, and it has obvious algae-green fluorescence on the obverse which is visible under UVA.

Under UVC that colour changes to a brighter aquamarine, not an obvious blue like the 2018 note.

 

I am trying to get other notes from this series, since this sort of variable interests me. Once I have done the proper photographs I will put them in the catalogue.

 

 

The lamp I use is good enough I suppose 😊, for all other banknotes it shows clear UV-A features exactly as it should. I'd have to add that I got all those 1997 notes from circulation shortly before they were demonetized, grades VG or G, which could be another reason for very faint or absent UV features. I didn't really put it here as some other problem to be solved though, it just surprised me a bit that 100 Kč is the only denomination where I couldn't see all features, that's all. 

Just out of curiosity, which prefixes of 100 Kč did you use for your UV observations?

The 1997 note is an H prefix

The 2018 note is an N prefix

I was lent two circulated notes today to photograph, both are 2018. 

First a 100 Korun with Y prefix. Left image is UVA and right image is UVC:

Then a 200 Korun with a K prefix. Left image is UVA and right image is UVC:

And these are my two notes discussed previously. First the 2018 with the N prefix. Left image is UVA and right image is UVC:

Next is my 1997 note with H prefix. Left image is UVA and right image is UVC:

Quite a few months passed between now and the original post. I am now more confident to say, based on the colour of the blue mark on your note it is a contaminant. The question is why it has such a nice straight edge on the right. It might be that the note had something else resting on it which prevented the spill from going to the right. But it seems like a contaminant not from the factory.

What was interesting now is that we know that more than one denomination has two UV responses. The 200 has red areas showing under UVC.

odd job

I was lent two circulated notes today to photograph, both are 2018. 

First a 100 Korun with Y prefix. Left image is UVA and right image is UVC:

 

 

Then a 200 Korun with a K prefix. Left image is UVA and right image is UVC:

 

 

And these are my two notes discussed previously. First the 2018 with the N prefix. Left image is UVA and right image is UVC:

 

 

Next is my 1997 note with H prefix. Left image is UVA and right image is UVC:

 

 

Quite a few months passed between now and the original post. I am now more confident to say, based on the colour of the blue mark on your note it is a contaminant. The question is why it has such a nice straight edge on the right. It might be that the note had something else resting on it which prevented the spill from going to the right. But it seems like a contaminant not from the factory.

 

What was interesting now is that we know that more than one denomination has two UV responses. The 200 has red areas showing under UVC.

Hey, I was wondering which UVC light you use? I'm pretty sure the light I have is UVA, which explains why I haven't been seeing your results on the right. Thanks!

Hi, I have a thread all about the UV lights here:

UVA vs UVC fluorescence: does anyone have real examples? [solved] – Numista

If you are going to be looking at UVC frequently, then you are best getting a mains-powered light. It needs three components:

1. The light fixture or socket for the bulb

2. A UVC bulb

3. A UV bandpass filter (a special piece of dark glass that stops visible light getting to the banknote)

So in my case I got these from Amazon:

And the filter glass from eBay:

Those three will be from £50 to £65 in total. Not cheap but once you have that, you have no problems. I use my light heavily and it is still working fine. Just be careful with the UVC light, don't shine it onto your skin!

The cheaper option is a battery-powered light but you will see if you read the thread I had a lot of issues with those lights becoming dim or being faulty out of the box. You will spend £40 for the light, then you need to get rechargeable batteries and you also will need spare bulbs, at £5 each.

And fitting the bulb is fiddly, you have to take the light apart.

odd job

Hi, I have a thread all about the UV lights here:

 

UVA vs UVC fluorescence: does anyone have real examples? [solved] – Numista

 

If you are going to be looking at UVC frequently, then you are best getting a mains-powered light. It needs three components:

 

1. The light fixture or socket for the bulb

2. A UVC bulb

3. A UV bandpass filter (a special piece of dark glass that stops visible light getting to the banknote)

 

So in my case I got these from Amazon:

 

 

 

 

And the filter glass from eBay:

 

 

Those three will be from £50 to £65 in total. Not cheap but once you have that, you have no problems. I use my light heavily and it is still working fine. Just be careful with the UVC light, don't shine it onto your skin!

 

The cheaper option is a battery-powered light but you will see if you read the thread I had a lot of issues with those lights becoming dim or being faulty out of the box. You will spend £40 for the light, then you need to get rechargeable batteries and you also will need spare bulbs, at £5 each.

And fitting the bulb is fiddly, you have to take the light apart.

Wow this is super helpful, thanks so much!

odd job

I was lent two circulated notes today to photograph, both are 2018. 

First a 100 Korun with Y prefix. Left image is UVA and right image is UVC:

 

 

Then a 200 Korun with a K prefix. Left image is UVA and right image is UVC:

 

 

And these are my two notes discussed previously. First the 2018 with the N prefix. Left image is UVA and right image is UVC:

 

 

Next is my 1997 note with H prefix. Left image is UVA and right image is UVC:

 

 

Quite a few months passed between now and the original post. I am now more confident to say, based on the colour of the blue mark on your note it is a contaminant. The question is why it has such a nice straight edge on the right. It might be that the note had something else resting on it which prevented the spill from going to the right. But it seems like a contaminant not from the factory.

 

What was interesting now is that we know that more than one denomination has two UV responses. The 200 has red areas showing under UVC.

Thanks for returning to this topic. People sometimes damage banknotes in quite improbable ways, so the origin of the blue mark might well be as you suggested. It's also nice that you shared the UV activity under different wavelengths, as it is not shown on the ČNB webpage or in the catalogue.