suggestions for UV / blacklight device

Many notes are using creative and beautiful designs which are only visible under UV light and I also noticed some pages in the catalogue where members are adding pictures that help point to some notes interesting features as well.

In order to further enjoy my collection (and maybe detect some counterfeits), I am considering the purchase of a device but I don't know what kind would be suitable for such purpose. I haven't found anything locally and after an internet search I found one from Banknote World, priced at 12.99USD in Amazon and which would ship to Finland (where I live) for 14.15USD; other lamps and pen-torches adverstised for about 20-40 bucks + S&H.

Is anyone familiar with these products or can suggest or recommend a similar and inexpensive light?

Will any UV or blacklight device work or are there specific considerations for banknotes?

Any and all comments will be much appreciated.

I have a cheap UV-C device and find it underwhelming. It's sufficient for detecting certain fakes and excites some inks but there are nicer (of course more expensive and a bit more dangerous) devices out there.

From an older post

At home I have a cheap ass handheld shortwave UV fluorescent lamp, with it's 254nm UV-C wavelenght it isn't optimal for most banknote security features.

The decontamination unit in our lab has a beefed up version of it and may yield better results.

But I'd really like to try a UV-A emitter to see something like this

From a Bank of England document:

> What type of ultraviolet (UV) lamp should I use to check a note 
is genuine?
A UV lamp which emits light at around 365 nanometres is ideal for checking the 
fluorescent features on all our notes. We do not advise using LED (Light Emitting 
Diode) devices, such as key-fob style detectors because these often emit light 
above 365 nanometres. Some counterfeiters do attempt to copy UV features, so 
make sure your staff know exactly what to look for, such as the colours we use 
in the UV numbers.

Link to said document if I can get it right

 https://www.bankofengland.co.uk/-/media/boe/files/banknotes/take-a-closer-look.pdf

Nice pictures @Idolenz, it would be interesting to see the same note under the different lights.

The lamp I mentioned above does not state the nanometres, the box only says that the lamp is 4 Watts UV.

So, Thank you @Idolenz and @waisaacs for the comments regarding wavelenghts, it appears that I need to modify my search parameters.

Here's a good discussion of UV light in general https://scied.ucar.edu/learning-zone/atmosphere/ultraviolet-uv-radiation

From it, 

UV-A, which is also called "blacklight" or "Long Wave" UV, spans wavelengths between 320 and 400 nm.

So “long wave” or UVA is probably what you want to look for in the device description if it doesn't go into the wavelength specifics.

I really need to buy myself a good UV light one of these days. 

Here's a fun video from Half Asleep Chris: 

I’ve been curious about which UV light device to use because I’ve researched and found out, most UV torches are not recommended to be used on banknotes and some real banknote checkers have poor reviews saying that the light isn’t “bright enough”.

As a bonus, you can use your new UV lamp to find scorpions at night, as they fluoresce a blue green under UV!   I won't include a photo in case anyone has an aversion, but it's an easy google.

waisaacs

As a bonus, you can use your new UV lamp to find scorpions at night, as they fluoresce a blue green under UV!   I won't include a photo in case anyone has an aversion, but it's an easy google.

🤣  I would have never thought of that, the search does produce interesting results.

Serial_Number_8

I really need to buy myself a good UV light one of these days. 

 

Here's a fun video from Half Asleep Chris: 

A very good video IMO, I actually the one that helped me decide to look for an UV light earlier this week.

waisaacs

Here's a good discussion of UV light in general https://scied.ucar.edu/learning-zone/atmosphere/ultraviolet-uv-radiation

 

From it, 

 

UV-A, which is also called "blacklight" or "Long Wave" UV, spans wavelengths between 320 and 400 nm.

 

So “long wave” or UVA is probably what you want to look for in the device description if it doesn't go into the wavelength specifics.

I think that this is the info I needed, I can now fully understand the different results in @Idolenz's pictures.

Thank you both.

Let's see if other members can tell about the UV devices they use for checking the banknotes and whether someone can recommend brands or guide as to the price ranges that can be expected.

I bought a battery operated flashlight for under 20$ from Home Depot, a hardware chain. It certainly gives a different view of my banknotes. There are many hidden items on your notes. Some notes the ink is only slightly active and hard to distinguish the UV active and inactive varieties. Could be the ink or could be the wavelength. The 1980 1 yuan has a UV varieties. Under my flashlight I can see the difference but it is not reaĺly clear. Could be my aging eyes too.

Being a retired physicist, I can't help myself, so thanks in advance for your patience.  

The ink being used in the banknotes is fluorescent under UV, meaning that it contains molecules that absorb particular wavelengths of UV light and then re-emit some other wavelength of light, in our case here some visible color.  The discussion here is around what kind of UV source is useful for seeing the emitted visible light.  I'll just mention a few things that are relevant (without being so actually useful as to recommend a particular device!).

The fluorescence is a proportional response - typically one (UV) photon absorbed and one (visible) photon emitted.  The number of photons from a source is called the luminosity, but what we care about here is the number of photons per unit area - the UV photons that get to the ink - and that is called the source brightness.  The luminosity of the source is generally proportional to the power it uses, so a 10 Watt lamp will put out twice as many photons as a 5 Watt lamp.   The brightness you can control by moving the source closer to the receiver.  For point sources, this goes like an inverse square: source twice as close will give you four times the brightness.  At some point with increasing source brightness, the fluorescent ink would saturate, meaning all the molecules are absorbing and emitting.  There's a limit to how luminous the fluorescence will get.  

So… now that I write this all out, I realize that it's common sense advice: get the UV source as close as you can to the ink, and dim the lights in the room to reduce the background light competing with the fluorescence.   But I hope it's useful or at least interesting to know what's behind common sense.

Best,

Bill

If you are just looking for a cheap easy to find light, I got one at an auto parts store. Some of the auto fluids have UV dye in them so you use flashlight to check for leaks. The one I have came with yellow/green glasses that when combined with the light makes the dye really stand out. I don't know if the glasses will help for banknotes, but the light is cheap and easy to find.

 So, Type UV-A (Long Wave) it is.

Thank you all for the comments, the more I got and the more notes and links I read have really conviced me to go for it.  Not only will I be able to  enjoy a lot more the banknotes, I will also be able to avoid horny scorpions and spilled car fluids . . . and perhaps start a new collection just dedicated to UV features.

For those interested in the subject, I recently discovered a Forum thread requesting UV features to have its own section in the Numista catalogue:  "UV features" section for banknote pages

Ruibai

 So, Type UV-A (Long Wave) it is.

 

Thank you all for the comments, the more I got and the more notes and links I read have really conviced me to go for it.  Not only will I be able to  enjoy a lot more the banknotes, I will also be able to avoid horny scorpions and spilled car fluids . . . and perhaps start a new collection just dedicated to UV features.

 

For those interested in the subject, I recently discovered a Forum thread requesting UV features to have its own section in the Numista catalogue:  "UV features" section for banknote pages

Hope to see the device in action when you receive it.

Hope to see the device in action when you receive it.

I hope that I eventually get to it and that I find interesting notes in my collection.

For now, I began looking for suitable lamps that I can afford. Most are priced between 12-70USD and all I find on Amazon charge about 15usd shipping to Finland (where I am now).  I also located some local shops here and already found at least two seemingly appropriate lamps for under 30euro.

In the meantime, while  I am still learning about different options and alternatives, I came accross some articles that tests various devices on banknotes, paint and other substances, and which might be of interest to other people who could also be looking for UV lamps. 

Here's some of them that will help you decide what to look for:

Best UV flashlights of 2023

What is the Best UV Flashlight?

Best UV Black Light Flashlight (June 2022)

Well, last night I settled for a 17.90 eur (incl. 24%VAT) basic, low-power flashlight at a local auto parts store and here are some of wonderful discoveries already made.

This will probably be all for now, the next step will be to explore the whole collection and to search for new notes that I would like to add just for their UV designs.

Thanks to all who contributed to this thread, the technical comments were specially useful for me.

If there are not already pictures in the comment section please add yours to the corresponding pages and maybe include something like

Banknote under UV light (XXX nm):

The above photos were quickly taken with the phone, to test the flashlight and just for the purpose of this discussion.

But, your point is well-taken, I will plan to take better photos and add the UV images to the Numista catalogue.

Warning: after just a few days, I am discovering that the usage of UV light to inspect banknotes (and other stuff around you) can be pretty addictive!

Although I noticed in above photo of a laboratory situation that no gloves appear to be in use :>0   

I assume that the use of eye (and hands?) protection is recommended; so, I wonder whether sunglasses or goggles that display a uv sign will do.

Or, should it be something else, for instance, for taking photos for the catalogue?

In the pics, what I have I home, I hope good enough . . .

Specs for the Uvex Skyper W 166 F goggles include “U6 grade -level filtering 99.9% of UVB/UVA protection for far and near UV transmittance”

while the FLADDEN sunglasses state that “they filter out all UV rays with a wavelength of up to 400 nanometers. This includes both UV-A and UV-B.”

What about the hands/skin?  Are cotton clothes enough or something else (like electrical insulation gloves) needed?

What are the minimum safety recommendations to follow when using UV lights in numismatics?

In the above picture the unit was on for a few seconds, the hand behind the light source and quite far away from reflective surfaces, so there was no greater risk then stepping outside when the sun is shining.

In a lab situation you usually deal with relative powerful emitters and you want to work as slow as necessary to guaranty quality work and as fast as possibly not to harm yourself or your samples. We wear long sleeved coats, nitrile gloves or other materials and a face shield, for example when you work with marked DNA on a UV work bench.

But in the end it depends on how powerful your UV source is, how long you expose yourself and how far away you are from the source and/or reflections.

The safety instructions are usually similar for any work with radiation sources be it nuclear or high energy EMR:

Do's:

• Wear appropriate personal protective equipment (safety glasses, UV-blocking face shield, gloves)
• Cover exposed skin (don’t forget the area around the neck!)
• Ensure others in the work area also have on proper PPE or ensure the work area is vacated prior to use
• Test exposed materials for UV- stability

Don'ts

• Don’t look into the radiation without safety glasses
• Don’t expose humans, animals and plants to UV radiation
• Don’t touch UV emitters and radiated surfaces. Risk of burns!
• Do not make any modifications to the equipment as the safety is then no longer guaranteed