Halloween Forum banner
1 - 20 of 27 Posts

·
Registered
Joined
·
1,686 Posts
Discussion Starter · #1 ·
What is the proper / best wavelength of a UV LED flightlight for Halloween purposes. Seems like there are various models of UV flashlights out there for different purposes like finding stains, scorpions, etc having different wavelength values. What wavelength of UV light works best for traditional Halloween "blacklight" effects?

And even better, if there's a particular model of UV LED flightlight you're purchased semi-recently, one that still might be for sale on eBay or Amazon, please post the model #.
 

·
Registered
Joined
·
304 Posts
It depends on what look you are going for , 365nm is invisible and makes things glow, 385 - 405 are shades of purple and the glow.

fleabay and china sellers are the cheapest place to get them, a couple dollars each
 

·
Registered
Joined
·
227 Posts
365 can do damage if you look at it for too long - be careful. 385 will give you a decent glow without too much worry about safety, although there is some danger.

I bought some of these a few months ago to test - not impressed. More of a purple/blue LED with minimal glow from UV reactive paint.

These made the UV paint glow better, but have to be fairly close to the item to be effective.
 

·
Registered
Joined
·
1,686 Posts
Discussion Starter · #4 ·
365 can do damage if you look at it for too long - be careful. 385 will give you a decent glow without too much worry about safety, although there is some danger.

I bought some of these a few months ago to test - not impressed. More of a purple/blue LED with minimal glow from UV reactive paint.

These made the UV paint glow better, but have to be fairly close to the item to be effective.
Thanks UntilLater and Hedg.
Hedg you were reading my mind--I was going to ask about UV wavelengths and safety.
 

·
Registered
Joined
·
304 Posts
365 can do damage if you look at it for too long - be careful.
Wow, that is pretty deceptive. It would be the same for any bright light.

The problem lies in that people cannot see the light to gauge how bright it is, therefore they don't look away or blink if it is too bright.

This really shouldn't be an issue unless you are making extremely bright spots and pointing them directly at people.

1) Most lights you buy would not be bright enough for this to be an issue.

2) if you plan where you point them, It doesnt matter anyway, IE directly at props away from people
 

·
Registered
Joined
·
304 Posts
The issue isn't how bright it is - UV radiation can cause radiation burns, cataracts, and can increase the risk of skin cancer. http://www.ehs.washington.edu/rsononion/uvlight.shtm
Again, your right but deceptive. Do you have any idea how long it would take for that to happen with say a 9 5mm LED 365nm blacklight flashlight. for most people it would take years....


The amount of UVA in a standard 365nm flashlight is no more than in a standard florescent 395nm blacklight. The only difference is the purple visible light

now that is not to say that there arent super bright/strong ones out there, but what you might actually use in a haunt.... no
 

·
Registered
Joined
·
227 Posts
Given a 20 mw per emitter output (180 mw total) one of those flashlights would exceed NIOSH's recommended eye exposure limits in 5000 seconds (83 minutes.) Probably wouldn't be a problem for kids coming & going, but an actor in a haunt could easily be exposed longer than that.
Better safe than sorry.
 

·
Registered
Joined
·
304 Posts
That would be putting the light directly in the eye an inch away.

I agree about being safe, always pays to be aware and use things properly.

pointing them at props though, the exposure to a person (eye) is so minute as to be irrelevant, just dont shine it on people
 

·
Registered
Joined
·
1,686 Posts
Discussion Starter · #10 ·
$2.50 LED Black Light @ Target / $8 Blacklight LED Mini Strobe

Bought two of these @ $2.50 each from the dollar/bargain section of Target. No idea what wavelength or amount of light they emit. Thought I would share for others interested in UV lighting this Halloween season:

Auto part Muffler Material property Cylinder Electronic device

Also from Target, purchased an $8 Black light mini strobe. Appears to be made by Gemmy. Again, don't know the UV wavelength. But any or all of these might be helpful for my haunted mailbox project.

Technology Electronic device Electronics

Light Automotive lighting

Would be interested in hearing about / seeing these units in actual Halloween scene applications.
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
365 nm is well within safe parameters (most UV fluorescent's have a decent amount of output down to 350 nm, and many standard fluorescent's reach down to the very same wavelengths). And to put this in there, bear in mind that the LED's would likely never be directly viewed. You will run into trouble faster directly viewing at much shorter wavelengths e.g.: < 340 nm, and progressively worse as it eclipses the UV-B & -C thresholds. But, the majority of the UV-A spectrum is quite minimal risk, you'd get more exposure from the bug zapper in your back yard over a weeks time, or just walking outside on a sunny day.


And on a personal note, I think NIOSH is more than a bit of a worry wart on their exposure recommendations compared to NEMA. With those guidelines they (NIOSH) state, you shouldn't spend more than 83 minutes in the sun w/o eye protection, ever in your entire lifetime. While safety is a valid concern, modern society would unrealistically have us living in a protective bubble, in the dark. Too much paranoia is a very bad thing imo.
 

·
Registered
Joined
·
227 Posts
I wasn't trying to be alarmist in my posts & stir things up - just trying to be safe. One of my jobs at work is to maintain a water bottling plant where we use UV as part of the purification process & I was required to go through NIOSH's certification training before I could get certified to work on the machines. Maybe the training made me over cautious - I don't know - but better safe than sorry. The chances of any permanent damage coming from exposure to 365 nm is slim, but there is still a chance. If the OP had several of those spots lighting his props and an actor in his haunt exposed to the UV light for extended periods there is a possibility of long term eye damage (cataracts being the most common.) This wouldn't happen immediately - cataracts can take years to manifest. If the lights are pointing away from the crowd and actor exposure is limited then 365 NM would be the way to go, because it's nearly invisible to the naked eye & makes things glow very well. But the fact that it's invisible to the naked eye is also part of what makes it risky, because you don't know if you're being exposed or not. Again, not trying to be alarmist, just wanting to make the OP aware of the potential danger & take the appropriate precautions.
 

·
black light queen
Joined
·
2,636 Posts
that black light strobe looks interesting

i'm guessing that it is probably very weak and not very effective

i believe that the 365nm leds are really expensive and that most are in the longer wavelength or blue/purple category

i'm thinking that if you were to look at a 365nm light you wouldn't see anything ... but you would see the light from the blue/purple leds or lights

black light compact florescent bulbs are cheap ... it there anyway to make a strobe using that ... one of the problems with florescent bulbs is that they need time to "warm up" and keep glowing for a brief period after the power is off ... probably the way to go using one of these bulbs would be use a mechanical shutter to strobe the light on & off ... probably very noisy as well

amk
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
Anyone know about this type? How it shines? How does it hook up? It's more costly but seems more powerful.

http://www.superbrightleds.com/more...ltraviolet-leds-140-degree-viewing-angle/334/

These are not the droids you are looking for. :D 410 nm is well into the blue spectrum, and will produce visible light that will appear purple. For all intensive purposes, you should be looking at no more than 380 nm, but preferably closer to 365nm. Below 355 nm wavelength would be acceptable,only if there is no chance of the LED being directly viewed under any circumstances.


That said, the LED you linked will be quite bright, purple, and have very little usable light output in the actual UV spectrum. Sorry. :(
 

·
Registered
Joined
·
154 Posts
Black Light LEDs are actually pretty terrible outside of just experimentation. You will not get the same effect you would with the fluorescent tube versions, there is just no substitute.
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
Black Light LEDs are actually pretty terrible outside of just experimentation. You will not get the same effect you would with the fluorescent tube versions, there is just no substitute.

I'm going to have to disagree with you on this. I will say that it depends on what you expect of them. If you want a wide angled cone of light output, then you have to take some additional steps, or use specialized LED that are made for a wide angle dispersion. e.g.: 3528, 5050, or straw hat package which normally have a dispersion angle of 90-140°.


A commonly available (and what most people would use) T-1 3/4 package is going to be fairly narrow angle (15-25*°), although the straw hat type are relatively the same dispersion angle compared to the 3528 or 5050's.


Now, light throw is a different subject entirely. Singular LED's will never throw as far as florescent bulbs, their brightness just isn't intense enough to do so. Unless however, they are of nearing 1/4 the wattage of the compared florescent. And then they will exceed them both in brightness and throw length substantially. But with the T-1 3/4, 3528, 5050, or even the 0406...that means literally hundreds (plural) of them.


The only advantage florescent black light bulbs have, is 360° light dispersion. But, as we all know, that last 90°-120° section is pretty well useless as it usually either reflected back via a reflector due to the housing necessary to hold the bulb blocking the light path, or not. Which is wasted light, and reflecting it causes it's own special set of phasing issues. Just playing the devils advocate here.


If on the other hand you purchased UV LED's that didn't make the same glow effect as a decent quality UV florescent, then that was a byproduct of purchasing the incorrect wavelength LED's. Unfortunately, not all manufacturers (in any industry, really) are completely transparent when marketing lingo is used. I'm sure everyone here at some point has purchased a florescent blacklight that didn't glow very well either, or worse...a "blacklight" incandescent. Same story applies to LED's sometimes too.


Just so I'm being transparent, I build UV (and any other type/color of) LED array(s) all of the time. Both for my customers, and for myself. This is one of my personal projects I'm working on atm, not completed mind you (waiting on some back ordered LED strips, specifically the one for the handle that shines towards the front). But it's a good shot of some of what I do with them.


Pardon my camera, it's not a fan of UV saturated shots.


Electronics Blue Light Violet Purple


...and a flash shot of what you're actually looking at.


Electronics Computer cooling Technology Cable management Electronic device
 

·
Registered
Joined
·
154 Posts
You didn't disagree at all... they are different, in wavelength and how much light output they have.
LEDs ride the edge of being ultra violet barely..not that great for lighting.
 

·
A 1 man army of darkness
Joined
·
2,586 Posts
You didn't disagree at all... they are different, in wavelength and how much light output they have.
LEDs ride the edge of being ultra violet barely..not that great for lighting.

On the wavelength being barely into the UV spectrum, I'm not sure how you figure that. Seeing how the shortest wavelength LED (an aluminum nitride doped) is deep into the UV-C spectrum at 210 nm. Which is nearly at vacuum UV, which is only 110 nm higher than the highest frequency of the x-ray spectrum.



http://www.led-professional.com/technology/light-generation/aluminum-nitride-light-emitting-diodes-with-the-shortest-wavelength-towards-dioxin-pcb-decomposition-technology



Although the play on words isn't lost on me, the commercially available as "black light" type florescent bulbs are "barely" into the UV spectrum either. As far as light output goes, 100w UV LED's are available, although they are on the bare cusp of being qualified as outputting UV @ 380-385 nm. Although they aren't commercially viable due to costs. Heh, you can even find them on Ebay.


The same cannot be said for more standardized output levels where it is easy to acquire them that go into the UV-C range. Short wavelength LED's from 360 nm to 245nm can be found readily below.


http://www.roithner-laser.at/led_deepuv.html


In short, yes we are definitely disagreeing. Even about being in a disagreement ;) :D
 

·
Registered
Joined
·
154 Posts
Awesome!

We should build some black light bars using LEDs that matches the Flourencent tube's 365nm output and undercut that action.
Let me know if you are down, we could start a kickstarter page or something.

Do you know the cost of the 365nm UV LEDs? I have to email that company you mentioned and find out.

Looks like the flat head has the widest range of the light output.

Looks like the light output of a fluorescent tube can vary, I couldn't find an exact number but a typical 15W fluorescent blacklight has between 675 to 3000 lumen output range which is pretty crazy wide, so I figure if we can get somewhere in the middle we would be alright.

I guess the question then becomes how many lumens does a single flat topped UV LED in the 365 range like our fluorescent put out?
If we could figure this out we could then figure out how many of those little guys we need to match our fluorescents.

Let me know because then I can get a hold of that company and see what the cost per LED would be and if we get enough of them we might be able to really give those tubes a run for their money. I suppose we need to make a power supply or find a cheap one that could run the system too, that might add a little cost.

I mean if we can get below the $15 mark you pay at home depot for a fluorescent tube with a lighting fixture then we could really make a killing off these.
 
1 - 20 of 27 Posts
Top