Let's nerd out about Blacklights

[melodiousdirge]

With my laser projects dead for this year, I'm thinking UV reactive stuff is going to be my substitute. I'm thinking/hoping this troupe probably has some expertise in all things UV reactive; mainly I'm focused on light sources right now. I want to create some cool fluorescing and phosphorescing effects, ideally without wasting money trying out a bunch of things before finding the right setup(s).

I found this page informative (The site sells stuff but this is a great write up offered for free): https://glowinc.com/glow-in-the-dark/black-light.aspx

Unfortunately their write-up is focused on phosphorescence and they recommend 365nm lights. The problems I have with 365nm emitters are:

• 365nm LEDs tend to be more expensive and less efficient than 395 and 405nm lamps.
• The narrow bandwidth (presuming LEDs) means only some things will light up under them. However they will light up some things that 395 and 405nm lamps will not, like scorpions, or security dye on passports or money. I'm wondering if there are a bunch of UV reactive substances I might be missing out on if I exclude 365nm LEDs from consideration.
• 365nm lamps come with warnings that they may damage your eyes. Now, I don't know if they have this label just because the light is invisible so one may find oneself staring into the light for a while and not knowing they were exposing their retinas to high levels of incoming light (pupils will not contract in reaction to 365nm light as I understand it), or if the short wavelength is what makes them dangerous.

Types of Lamps I've considered:

• Incandescent bulbs with blb coating: Only mentioned for completeness - these are utter crap, and are not recommended by anyone who's tried one.
• CFL screw in bulbs: These work well, but they are low wattage - basically a miniature version of a fluorescent tube.
• Fluorescent tubes: A 4' fluorescent tube or two will illuminate a good sized room, and in my experience produce a tasty glow from most UV reactive substances, but they DO throw a lot of visible violet light. This is totally OK as far as I'm concerned, but the visible light tends to wash out the glowing from some substances (like security ink etc.) The drawback for burning man with these is they require 120v, and I'd really prefer something that will take 12v. These are also pretty fragile to be carting out to the desert and back.
• Mercury Vapor: A couple of manufacturers make 400W mercury vapor blacklights for big parties. One of these inside my dome (or my house) would be nothing short of freaking awesome, but I have never seen one in person, and I'm curious about the light it puts out. Lots of visible light? Does it put out lots of shorter wave UV that makes security dye glow? Eye protection required? These gobble a metric swass-ton of power - as much as 10 fluorescent tubes, and would have to be pretty awesome to be worthwhile; I'd love to hear about anyone's experience with them. I also hear these get extremely hot, and need to be treated with caution.
• LEDs!! I'd really love to hear people's experience with LEDs, because this is where there seems to be a lot of potential, but also things get a bit technical and complicated. The other light sources have somewhat broad spectrum output, but an LED puts out a very specific wavelength. UV LEDs come in a bunch of different flavors, generally with the shorter 365-385nm wavelengths being more expensive than the longer 395-405 wavelengths. I have used a 5mm 405nm LED to light up UV reactive makeup and contacts with great success, but I'm thinking bigger now. Several manufacturers are making relatively affordable LED blacklight bars, but they don't look that impressive for the money (a fixture with similar output to a fluorescent tube is anywhere from $99-$199, compared to $40ish for a tube fixture with bulb). The main attraction here is the efficiency and 12v compatibility. What I'd like to do is get a cheap pair of 12v LED flood lamps (already have, actually) and replace the emitters with UV emitters. The question is which wavelength(s) will give me the best balance/widest array of fluorescence? I've considered installing 365, 395 and 405s all in one array, but I'm worried then I'll get fluorescence from a wide array of things, but without a whole lot of oomph. It's also cheaper to buy a large lot of one wavelength than small quantities of several. Does anyone have any experience on this? I'm leaning towards splitting the difference and putting in 395s for starters and seeing where it takes me.

[melodiousdirge]

Oh! I'm sure someone is going to ask if I have any specifics on what I'm trying to do; right now I'm trying to gather as much info as possible, generate a long ass list of ideas, and pare it down to what fits my budget. There is so much tech coming of age every year that it's a new learning experience each time. Some projects I'm considering are:

• Strong blacklight illumination for the inside of my 24ft dome. Ideally strong enough to find your way around, without any additional light.
• Blacklight flashlight, for forays out to the trash fence, with only the fluorescence of objects around me for guidance. Bonus points for the ability to circumnavigate pools of bodily fluids.
• Upgrade my LED UV collar that shines blacklight on my face from some 12" long antennas in front of my face. Creates a cool effect of glowing makeup/contacts even out in the darkness.
• Swapping out of the white LEDs in one of my headlamps to UV leds. Not recommended for use in portapotties for peace of mind.
• Battery powered umbrella with strong UV LEDs on the underside, to be carried around at night to make my glowy shit glow. Need to work out a way to make it wind-transparent so it doesn't get shredded. Could add a solar panel to the top for daytime parasol use if I become really ambitious.

I'd also love to hear people's ideas for things that actually glow. There's the plethora of stuff onlone that purports to be UV reactive, but I've had mixed success. Balloons, Cups, Makeup, Bubbles, all that crap seems like fun but I've never had bubbles work out. Never tried some of the other ones.

Some cool ideas I've seen are club soda for glowing drinks, RIT fabric whitener on anything, highlighters, fluorescent paint, etc. I'd love to know about any food-safe fluorescent additives anyone might know of as well, as glowing drinks, or jello would be cool, or squirt guns with food safe glowing liquid. Many possibilities.

[Zhust]

• 365nm lamps come with warnings that they may damage your eyes. Now, I don't know if they have this label just because the light is invisible so one may find oneself staring into the light for a while and not knowing they were exposing their retinas to high levels of incoming light (pupils will not contract in reaction to 365nm light as I understand it), or if the short wavelength is what makes them dangerous.

If I recall correctly, wavelength is bad—more energy there than meets the eye —but it's more to do with it being nearly a point-source. A 10W UV LED puts all its power in 1 square millimeter while a 10W fluorescent distributes its light across a large area (18" tube 1" in diameter would be like 35,000 square millimeters). Now you're back to the laser problem: a tiny dot of high power on the retina ... oops. Wear sunglasses ... I have these cool clear ones that block UV (easy test: shine UV LED through glasses and test for fluorescence of fluorescent materials.)

As for any safety advice beyond that, I have no idea.

[melodiousdirge]

If I recall correctly, wavelength is bad—more energy there than meets the eye —but it's more to do with it being nearly a point-source. A 10W UV LED puts all its power in 1 square millimeter while a 10W fluorescent distributes its light across a large area (18" tube 1" in diameter would be like 35,000 square millimeters). Now you're back to the laser problem: a tiny dot of high power on the retina ... oops. Wear sunglasses ... I have these cool clear ones that block UV (easy test: shine UV LED through glasses and test for fluorescence of fluorescent materials.)

As for any safety advice beyond that, I have no idea.

I believe you are correct that shorter wavelength is higher energy/more damaging. I just don't know how dramatic this effect is - intuitively it doesn't seem like there ought to be much difference between 395 and 365nm, but light is a funny thing in that only specific wavelengths can penetrate certain mediums - it could be that your eyeball is more permeable to 365nm light than 395nm; maybe it's a combination of the danger of staring into an invisible high intensity radiation source, AND the shortness of the waves; Iunno. I CAN say that two 395-405nm 5mm LEDs shining at my face to light up UV makeup and contacts becomes uncomfortable after a few hours, but I don't recall any lasting aftereffects like a retina burn (which I have experienced before from a welding arc, so I would probably recognize).

Interesting point on the luminous intensity; I hadn't really thought about that. I was quite tempted by some of the high powered UV leds made by 'luminous devices' - they produce a 17.7 watt emitter that is only 4.6x2.6mm in size (smaller than a regular 80mw 5mm LED) which would pose a more or less instantaneous eye damage risk. I do have a 10w red emitter that definitely requires eye protection even at a distance, and at the long wavelength. Even a 3w white emitter is blinding if you look directly at it. Maybe power density isn't everything in this case.

[trilobyte]

Glow Inc makes some great stuff, but I've found that a lot of their performance numbers either tend to be padded, or they're at least stretching the definition of what it means to glow (maybe they're using a light sensor). That said, if you've got a UV source within range to 'charge' it, they look phenomenal all night.

Yep, the LED's that get closer to the ideal frequency cost more and use more energy. IMO, the more common (and less expensive) 390-395nm wavelength stuff works quite well. I got a couple UV LED bars to flood each side of my camp's frontage with UV light, it not only picks up on any glow-tastic materials but also anything remotely fluorescent that any of our visitors are wearing. I put one 1-meter fixture (which uses 60 watts of juice) on each side of the ziggurat and that covers everything at ground level, then last year I added a half-meter bar (30 watts) to the roof of the shade structure at the top to make sure that all the detailed railing panels really popped.

For this year, I'm planning to replace a few UV light bulbs we have at other various places in camp (for atmosphere) with LED bulbs. I already got the bulbs and have tested them at home, they're in that same ballpark (390-395) and do a similarly excellent job with fluorescent and UV reactive paints and fabrics.

As an added bonus, the LED's generate very little in the way of heat and are infinitely more ruggedized than other bulbs. Seriously, these bulbs and fixtures will probably last a lot longer than I will. I suggest you pick up a bulb or fixture of the type you're considering and try it out. I did that when I was first building the Ziggurati installation in 2013, and I got a lot of peace of mind from being able to test paints and materials along the way. I think you'll be pleasantly surprised with how it performs (and if not you'll know definitively and can move on to another solution), and it will allow you to save the budget for other parts of the project.

[melodiousdirge]

Alright so I've tried a few things since the original Post. I've been testing stuff in a room about the same volume as the inside of my dome (room is about 14x20, dome is 23' round.)

Eliminator lighting 48" T8 fluorescent tube & fixture (bought as a unit) ($36):

• This fixture is pretty cheap and crappy, and seems unlikely to survive a trip to the desert, but it does work
• Cord is way to short to be usable without an extension.
• It would have been cheaper to buy a $13 single tube fixture from the hardware store, a $13 GE T12 bulb from amazon (or $20 at the hardware store), AND a $5 25 foot cord.
• The lamp provides about half of what I'd consider decent coverage for my the 14x20 foot room I tested it in. The single lamp is enough to see mild fluorescence in all parts of the room, but it's only really deliciously bright within about 6 feet of the lamp. For maximum tasty fluorescence, I think I'd mount one of these vertically in each corner, one on each wall, or 4 evenly spaced along the ceiling.

Eliminator lighting 24" T8 tube & fixture ($23)

• This is about the right size to blacklight a very small room (like the bathroom - if you dare)
• As long as we're discussing the bathroom; I'd like to note that this lamp does not seem to make any, erm, splotches glow. Depending on what you want the lamp for, this could be arguably good or bad. I couldn't find any pet stains with it either, on an old rug that I'm sure has at least one.
• At $23, this is pretty expensive for the amount of light you get. Like I said it's good if it's all you have room for, and you don't want to replace your regular bulbs with B/L CFLs.

Sleeklighting 13w CFLs ($12.99 for 2)

• watt for watt, not as bright as the fluorescent tubes, BUT, they throw light in all directions, which most tube fixtures do not. (I know you can get tube fixtures that DO, but they are awkward and fragile - most ceiling mounted ones have a limited angle of light throw).
• 3 of these provide about the exquivalent brightness all over a room as the 24" eliminator fixture, but with much more even coverage.
• These also get quite hot, which explains part of why they produce less light per watt.

9 LED/3xAAA flashlight($0) with the 9 LEDs swapped for 405nm units I had a bunch of laying around (also $0)

• Obviously not something I expected to knock my socks off
• Having said that, surprisingly strong, bright and effective. Despite the low wattage, 5mm LEDs (60mW each, so ~0.5W total)
• These 405nm LEDs do not make pet stains show up, but they make highlighters glow, and they light up security features in my driver licenses almost as well as the tube lights do.
• The blacklight flashlight is a lot of fun if you like blacklights (I've never had one before), and makes exploring your house at night a bit of a trip. I'm looking forward to trying a higher wattage, shorter wavelength unit. Unfortunately I haven't found a well reviewed 3w+ unit for under $50. There are plenty like the one I made in the $10 range, but I'm looking for some real power - UV night hike kind of power.

[melodiousdirge]

TL;DR - Thanks Trilo!

Glow Inc makes some great stuff...

That's good to hear. They seem to lay claim to being THE source of phosphorescent paints and materials for the whole world, but their stuff is very expensive. I kind of want to make something absurd like a molded silicone octopus with a heavy dose of their V10 powder - you know, something to toss at tripping strangers in the middle of the deep playa at night and yell "catch!"

I got a couple UV LED bars...

I forget the commodification rules; can you share the brand/models you're using? I think you're right that they likely use an emitter with a peak at 395nm. Every decent sized emitter I can find at 365nm is very expensive (like $5 each for 3w from an ebay china seller, running up to $100+ each for a 17w emitter from digikey).

For this year, I'm planning to replace a few UV light bulbs we have at other various places in camp (for atmosphere) with LED bulbs. I already got the bulbs and have tested them at home, they're in that same ballpark (390-395) and do a similarly excellent job with fluorescent and UV reactive paints and fabrics.

Cool - I have not looked into the screw-in bulb solutions quite yet (I'm assuming you mean the LEDs pasted to the outside of a pod, with a screw in base like a normal light bulb, yes?). Those seem like a big step up from a screw in CFL. One thing I just discovered yesterday is that those 5050 SMD LED strips that are becoming so popular are now available with 395nm emitters for about $20 for a 5m roll. This might be a fantastical way to install an even, diffuse blacklight around a space. Each 5m string about 15w, but likely produces as much light as a 4 foot (40w) tube (I still need to test this)

LED's generate very little in the way of heat and are infinitely more ruggedized than other bulbs.

Again, I'd love to know what brand you're using. The 48" fixture I have is definitely not anything I would consider calling "rugged", and the LED UV bars I've seen are difficult to assess from the pictures. The only products I've seen that appear to use heavy duty construction are the 400+w mercury vapor units.

I suggest you pick up a bulb or fixture of the type you're considering...

Agreed - that's sort of where I'm at. I have a BAD tendency to go crazy and buy one of everything and either not use half of it, or discover later that I could have gotten a better solution for less money than I spent going "SQUEEEEE!!", so that's why I'm seeking input while I (attempt to) restrain myself.

[Jovankat]

I don't have anything useful to add at this stage but I wanted to say I'm finding this super interesting and useful. Thanks chaps!

[melodiousdirge]

Haven't broken much ground on this lately - I'm still waiting for my 3w 395 nm emitters to show up so I can solder them into my flood lamps and see how well that works. The 18w flood lamps I have came with white LEDs and they are quite simply obnoxiously bright, so hopefully I get some oomph out of the UV bulbs, though it obviously won't be quite as dramatic as the white LEDs.

I have discovered that exploring your house at night with a UV flashlight is a pretty fun adventure - old fluorescent price tags, ribbons, weird reactive bits of lint, I even found a can of spraypaint I had no idea was fluorescent paint before last night.

I also discovered a couple of food safe fluorescent materials:

• Quinine is the crap in tonic water that makes a gin and tonic glow blue under blacklight, but it's hard to get pure quinine, and it tastes like shit, so it's sort of hard to add a pinch of it to things. It can also produce adverse reactions in some people, especially if you're not careful about the amount you use.
• Riboflavin is vitamin B2 and it glows green almost as brightly as fluorescine, even in very tiny amounts. I'll be making some B2 enhanced beverages and food items I think.

I also found that the phosphors in fabric whitener produce an awesome blue glow under UV light. Drips next to my washing machine from the detergent bottle look like a radioactive spill under UV light. RIT fabric whitener is supposed to produce pretty amazing results if you just use the whitener on the fabric and skip the rinse cycle, but I haven't tried that yet. I'm not sure if it would be irritating to skin or not, but I did find that after getting liquid detergent on my hands, and rinsing it off that my hands still glowed brightly wherever the detergent had touched them, but the little bit that was left behind to glow didn't seem to irritate me.

[CyanEssence]

I did some experimenting with UV-reactive paints a few years ago, and found two products that produce an interesting effect when combined (the picture is below, sorry about the labels, they got all messed up in some kind of creative furry apparently).

I painted with them in alternating layers (eg. one layer of glow-in-the-dark, let dry, one layer of UV-reactive, let dry, one layer of glow-in-the-dark... repeated until it's as white as you need, or produces an effect that is sufficient in your mind). This creates an awesome effect where blacklight not only causes it to react, but it then glows brightly (relative to how much UV-exposure the area gets) after the blacklight is removed.

I did this on a mask, and found that I could could "draw" on it with a keychain blacklight (held closely to the surface), and the image would hold for 20-40 seconds. I think it would be cool to do this with a canvas, and let people borrow/have keychain blacklights so they could draw on it - interactive blacklight create-your-own-ethereal-art!

For food, turmeric, a spice, is blacklight responsive, and pretty good for you too. I've seen my taco fillings, laced with moderate amounts of fresh turmeric, glow nicely under blacklight. The downside, if you want to call it that, is that you can also see it (under blacklight) all over your lips and hands for a while after eating it.

I don't know if this works with dried turmeric, but I am sure it would.

Glow Paints.jpg

[CyanEssence]

Fury, not furry....

[caffeineslinger]

Lot's of stuff glows under a black light...

[media]

Sorry. I couldn't resist.

[melodiousdirge]

I did some experimenting with UV-reactive paints a few years ago, and found two products that produce an interesting effect when combined (the picture is below, sorry about the labels, they got all messed up in some kind of creative furry apparently).

I painted with them in alternating layers (eg. one layer of glow-in-the-dark, let dry, one layer of UV-reactive, let dry, one layer of glow-in-the-dark... repeated until it's as white as you need, or produces an effect that is sufficient in your mind). This creates an awesome effect where blacklight not only causes it to react, but it then glows brightly (relative to how much UV-exposure the area gets) after the blacklight is removed.

I did this on a mask, and found that I could could "draw" on it with a keychain blacklight (held closely to the surface), and the image would hold for 20-40 seconds. I think it would be cool to do this with a canvas, and let people borrow/have keychain blacklights so they could draw on it - interactive blacklight create-your-own-ethereal-art!

For food, turmeric, a spice, is blacklight responsive, and pretty good for you too. I've seen my taco fillings, laced with moderate amounts of fresh turmeric, glow nicely under blacklight. The downside, if you want to call it that, is that you can also see it (under blacklight) all over your lips and hands for a while after eating it.

I don't know if this works with dried turmeric, but I am sure it would.

Now that is a cool idea. I happen to have a high powered 405nm laser, too (yes I know they are banned, it's ridiculously powerful and it never leaves my house for that reason, i'm just thinking out loud)... you could make some VERY cool effects as the laser light would be intense enough to charge the glow paint fully in a near instant. Electronic displays that project moving patterns onto the surface would make this crazy fluorescing pattern that appeared to leave slowly fading motion trails... *strokes chin thoughtfully*

[CyanEssence]

Nice, I knew it would be better to share this than keep it in my personal art collection.

Let me know if you do this (anyone) and I will make my way to your camp to see it.

I plan on doing this myself, for my home, but I am not sure if I will bring it to the playa. Probably will, I mean its not like bringing something that took me 100 hours + to paint.

Thinking of that, I would like to know what people use over their paintings to protect them from the playa conditions. I'm kind of surprised when I see paintings out there that have obviously taken someone a lot of time to do. I'm guessing that they put some protective layer over the medium they used, like a varnish. I wonder how easily dust comes off...

[melodiousdirge]

I'm guessing that they put some protective layer over the medium they used, like a varnish. I wonder how easily dust comes off...

I know very little about artistic paint mediums, but I'd think depending on what paint you used on the canvas, any of polyurethane, lacquer, or or acrylic clearcoat would do a pretty good job, but anything with a rough surface texture is going to be near impossible to clean the dust off of.

[CyanEssence]

I'll do a little research on finishes and just go ahead and do a few small UV/glow-paint layered canvases for this year (hopefully, still waiting on a ticket). I'll bring them out and see what kind of finish makes it easiest to clean off.

Let me know if you go ahead with the UV-based set up at your camp, I can bring one over to you if you'd like.

Thanks melodiousdirge, you've inspired me to actually put my idea into action!

[CyanEssence]

Now that is a cool idea. I happen to have a high powered 405nm laser, too (yes I know they are banned, it's ridiculously powerful and it never leaves my house for that reason, i'm just thinking out loud)... you could make some VERY cool effects as the laser light would be intense enough to charge the glow paint fully in a near instant. Electronic displays that project moving patterns onto the surface would make this crazy fluorescing pattern that appeared to leave slowly fading motion trails... *strokes chin thoughtfully*

I just took the mask I made, the one that led to the discovery I mentioned before, and tried comparing a handheld laser with a keychain blacklight. The handheld laser did almost nothing to charge the glowing. I have no idea about the power of the laser, but I can tell you it is a flashlight that has three settings: white LED, UV LED, and red laser.

Perhaps a stronger laser would work though. If it does, I'm imagining a large canvas with the layered paints, and a programed set of such lasers projecting images for a second or so, and then going off. Images like mandalas and intense geometric patterning would be amazing. I also like the movement idea that you mentioned, that would be cool to combine the geometry idea and the movement. There has to be a way to make this safe for playa use, thus making it allowable according to the BORG.

Also, I just noticed that I covered the mask with acrylic finish, and there is no dust on it at all. It is fairly glossy though, which may not be so great for all paintings. I may have bought a gloss finish, rather than matte finish. I'll have to check after work.

I'm pretty much done with school work for the semester, so I will make a small canvas tonight and test it out in a few days when it's done, using as many light sources as I have/can borrow. I'll keep you posted.

[melodiousdirge]

I did a bit of googling, and I think glow in the dark paint gets much more of a kick from shorter wavelength light (blue-violet) than from long wavelength like red. In fact I think the light has to be higher energy than the yellow/green glow in order to charge the glow at all (think ROY-G-BIV - higher energy colors are on the right, so you need a blue-violet or ultraviolet light to charge glow paint). Check this video out:

[melodiousdirge]

If everyone will tolerate my pontificating about how glow paint works for a sec (I feel like I wasn't super clear what I meant about wavelengths in the last post):

Glow paint (phosphorescence) and fluorescence work in similar ways, in that the material absorbs a high energy photon, hangs onto it briefly, and then lets it go as a lower energy wavelength. Glow stuff hangs onto the energy for a long time, while fluorescence re-emits the light immediately. Either way the point is that in order to get any effect, you need to supply a higher energy photon than the ones that get emitted. So in the case of a yellow highlighter, you need to provide a higher energy light than yellow to get any fluorescence, and up to a limit, shorter is better. That's why you generally need UV light to get that cool fluorescent light from one. Same thing with a green glow paint; it has to be charged with blue, indigo, violet or ultraviolet light in order to actually work. Shining a red, orange or yellow light on it (in theory anyway) won't do anything.

[melodiousdirge]

So my 385nm, 3w emitters finally arrived the other day. I mentioned earlier that one project I wanted to do in this vein was to take some obnoxiously bright 18w LED flood lights from ebay ($20-$30 for a pair) and remove the white emitters, replace with 3w, 385nm emitters (about $1.20 per emitter). Last night I finished swapping out the LEDs, and I have to say I'm very impressed with the initial performance. I'm into this pair of lights for about $40 total, and they are very impressive. They vastly outperform my $40, 40w Eliminator fluorescent tube light. The throw is more directional though, so for lighting a room you would need several. Just hooking one of these up to a power supply in my kitchen just after dusk (so still a little bit of light pollution in the room) I could brightly illuminate the white blanket on my bed, 25 feet away. These are bright enough that they cause afterimages if you accidentally look into one, even for a fraction of a second (note to self: consider a diffuser).

So the conclusion here is if you're willing do do a few hours' work, you can put together a very powerful pair of UV floodlights for about the same cost as a much more subdued 40w fixture.

Now... I see a used 400w mercury vapor ballast on eBay for $15. hmm

[melodiousdirge]

So my 385nm, 3w emitters finally arrived the other day

I forgot to mention I bought 20 of these, and only needed 12 for the floodlights. The other 8 were going to get mounted to the 8 arms of a folding umbrella, so I can carry around my own UV party and be brightly lit by an invisible light source at night. I'm reconsidering using these LEDs now though, just because they are so insanely bright, it might ACTUALLY be too much. We'll see. On the flip side, I was thinking that if I do decide to stick with 3 watt emitters for the umbrella, I might as well spend another $20 and get myself 365nm emitters, so the glow from the LEDs will be invisible on anything but a fluorescing surface. That way the light effect will appear to come from nowhere, and be extremely bright, even at a distance.

(Note to self; get some yellow UV blocking glasses to avoid eye strain if you go with the 3w emitters)

[melodiousdirge]

I could brightly illuminate the white blanket on my bed, 25 feet away.

It's worth noting that my blanket is freshly washed and white... it doesn't glow for the reason hotel blankets glow.

[melodiousdirge]

Learned an idiot lesson today. The flood lights I replaced the LEDs in had a waterproof coating to protect the electronics from the elements. Since I'd disturbed the coating I applied a fresh silicone conformal coating over everything to restore the weather resistance. Later when playing with the lamps I notice they are putting out a decidedly blue light instead of blacklight like before. Read conformal coating can and see that it contains a UV indicator so you can see where you've sprayed. Since it's been sprayed over the LEDs, most of the the UV light is being absorbed by the coating and re-emitted as blue. Luckily enough Acetone seems to remove the dried coating, but I felt like a dumbass.

On the bright side, this conformal coating is basically a satin clear coat I can spray onto anything I want to glow. Unfortunately it's $20/can so it shall be used sparingly.

[melodiousdirge]

Lot's of stuff glows under a black light...

I just got around to watching this for some reason. HA! Thanks for sharing.

[melodiousdirge]

USPS indicates that a reclaimed 400W Mercury Vapor ballast has been delivered to my door, along with a 400W Mercury Vapor black light bulb. Stay tuned; I may just be able to create a disgusting amount of glowtasticness for about $45 in parts.

[Token]

USPS indicates that a reclaimed 400W Mercury Vapor ballast has been delivered to my door, along with a 400W Mercury Vapor black light bulb. Stay tuned; I may just be able to create a disgusting amount of glowtasticness for about $45 in parts.

Kill some germs too.

Maybe a touch of melanoma in due time?

Is the Hg lamp upper UVC? I can't remember anymore. ~250nm or somesuch?

[melodiousdirge]

The Hg vapor emits mostly short wave light - I don't know what the spectrum is, but the lamp is the same dark purple that any other blacklight is, I guess I should look and make sure it filters out the UVA and UVB. After playing with it last night my eyeballs definitely felt like they'd been irradiated, but that might have just been because I was so close to the high intensity UVC.

The scavenged parts seem to work just as expected when fed 110VAC, so I'll need to make a little fixture for all the parts. The bulb burned a black spot on some cardboard and filled my garage with smoke in the 15 minutes I had it on, so I'll definitely need to be putting something together to hold the bulb away from surfaces, including a finger guard to keep the curious safe.

[some seeing eye]

You can look up the line spectrum for any element, including mercury. Glass and whatever coatings they use will reduce some.

[melodiousdirge]

You can look up the line spectrum for any element, including mercury. Glass and whatever coatings they use will reduce some.

Well I know the line spectrum, but the bulb manufacturer doesn't exactly provide a datasheet on the glass coating they used on the bulb. Mercury vapor has a peak as low as 254, but the glass itself likely filters most of this out. It also has peaks in the visible range, also filtered out by the dark coating. Based on this picture I assume the bulk of the light coming out is 350-405nm, with the 405 being the visible purple glow. Either way, I'd advise anyone playing with one of these not to look directly at it without protective glasses; my eyes didn't feel UV burned, but sort of like they do after an optometrist shines a bright light in there to check on my retina.

[FlyingMonkey]

That's HUGE!

Now if you had a couple of those, a mirror, & a lens, you could make a UV spotlight & give the man a nice tan.

Actually, that light scares me a little.