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Best Black Light LED Wavelength??

9394 Views 4 Replies 3 Participants Last post by  The Pod
Hey folks, I'm trying to find out the "best" wavelength for true black light effect from LED's. I am trying to get a vendor to market a black light version of their DMX led flood light kits. The question is what wavelength LED is best?

I found some sources online including the following from Glowinc.com that notes 365nm is the best for true blacklight. Anyone have any reason this would not be accurate???

To see what I am thinking about here is a link to the lights I use in my Haunt. I think if we could get this kit in blacklight it would be fantastic for low cost/wattage lighting.


The wavelength of light emitted from an LED is very specific. When you buy an LED, you can specify exactly what wavelength you wish it to emit. Ideally, for black lights, you would use 365 nm LED’s.

Therefore, you would assume that manufacturers of black light products would stick to that wavelength. Why do they not do that?

A 365 nm LED is only about 20% efficient as a 405 nm LED. Individual 365 nm LED's are also relatively expensive. Therefore, manufacturers need a massive number of expensive LEDs to create a decent LED Blacklight.

Furthermore, light from true 365 nm LED’s is not visible and therefore uneducated consumers are not happy with the "light output".

The popular stage lighting company, Chauvet, released a “black light” consisting of 192 “UV” LEDs. This product is a great VIOLET light using 405 nm, visible light, violet LED’s. However, it is almost completely useless as a black light. You can understand their reasoning when several DJ’s reviewed this light as “much brighter” than more powerful fixtures emitting true long wave ultraviolet light. The reviewers were making this determination by how much light they could see. Properly, they should have used fluorescent paint to determine the best fixture.

Flashlight manufacturer Inova, makes a “UV” flashlight with 3 365 nm LED’s and 2 405 nm LED’s for the same reason.

LED’s use relatively low electricity and emit almost no heat . They turn on instantly and can be very bright. They also have an extremely long bulb life.

If you select an LED fixture, you just need to make sure that the product you are buying includes 365 nm LED’s.

Currently, LED fixtures of similar power are 10-20 times more expensive then standard fluorescent black lights
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yeah, 365nm is the sweet spot!

i have a led flashlight with true 365nm output ... its not very bright ... but when its pointed at uv reactive material, it really fluoresces brightly

if you can see a bright violet light cast from the led, then its not 365nm

unfortunately 365nm leds are crazy expensive :-(

Thanks for the input. Any idea what "crazy expensive" is?
i haven't looked for 365nm leds for a long time ... i'm certain/hopeful the price has dropped ... but when i looked they were way out of my budget ...

maybe i'll have to look again ... hopefully i'll be surprised with a huge price drop

True, 365 is the perfect wavelength for UV. Problem is they are not very bright. A couple years back I bought a bunch of different LED styles and wavelengths to test with. The ones in the 365 wavelength that I tested ran me about $5+ a piece and were good to about 4"-6" away max. I found that if you go to a 395-405 wavelength, the price is reasonable and they seem to work with 90% of UV reactive items (paints, glow in dark colors, etc.). I could get usually find LEDs in this range for under a buck a piece or less. Range I could get up to 3'-4' distance and still get some UV reaction. I would have to say the brightest bang for the buck are the 1/2 watt 5mm Superflux style, although these tended to get hot/warm while on (enough to melt hot glue sticks). What I have been using now are just the standard 5mm Superflux 395-405. I can place these 1'-2' away from what I want the effect on and they work with 90% of everything I've tried.
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