# Fun with Black Lights.... **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [November 19, 2005, 2:43am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758 "2005-11-19T02:43:30Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![pool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pool/32/4152_2.png) [@pool](https://boards.straightdope.com/u/pool)\ **Post date:** [November 20, 2005, 3:30am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/21 "2005-11-20T03:30:06Z")
stretch marks ---
**Author:** ![Pixiesnix](https://avatars.discourse-cdn.com/v4/letter/p/898d66/32.png) [@Pixiesnix](https://boards.straightdope.com/u/Pixiesnix)\ **Post date:** [November 20, 2005, 7:35am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/22 "2005-11-20T07:35:56Z")
“Everybody looks good under a black light. Except me. Because I was under the impression that the mustard stain had come out.”–Mitch Hedberg ---
**Author:** ![neutron\_star](https://avatars.discourse-cdn.com/v4/letter/n/51bf81/32.png) [@neutron\_star](https://boards.straightdope.com/u/neutron_star)\ **Post date:** [November 20, 2005, 8:01am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/23 "2005-11-20T08:01:22Z")
You can do [some cool stuff](http://www.metku.net/?sect=view&n=1&path=mods/uv_drawing/index_eng) with UV reactive ink. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [November 20, 2005, 4:25pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/24 "2005-11-20T16:25:04Z")
> [@Burrido](#): > > Dunno if its true, but a stoner friend said he flicked tide all over his walls to get a planetarium like effect with the blacklight on. Yup, it’s true. Detergent glows like a motherfuck under a blacklight. ---
**Author:** ![Moe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/moe/32/2972_2.png) [@Moe](https://boards.straightdope.com/u/Moe)\ **Post date:** [November 20, 2005, 4:58pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/25 "2005-11-20T16:58:18Z")
> [@Burrido](#): > > Dunno if its true, but a stoner friend said he flicked tide all over his walls to get a planetarium like effect with the blacklight on. Absolutely true. My first year in college, often when we were, …er, feeling a bit funny, we’d break out the liquid tide and just go Pollack in every direction. By the end of the school year more of the room was covered in Tide than not. Our room sure did smell clean. What’s great is that it’s nearly completely invisible when the black light is off. We often joked about how next year’s tenants of the room would react if they happened to bring in a blacklight and turn it on for the first time. ---
**Author:** ![Burrido](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@Burrido](https://boards.straightdope.com/u/Burrido)\ **Post date:** [November 20, 2005, 7:07pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/26 "2005-11-20T19:07:01Z")
> [@Moe](#): > > We often joked about how next year’s tenants of the room would react if they happened to bring in a blacklight and turn it on for the first time. Hmm, howabout writing “BLOODY MURDER!!” on walls and giving them the shits. ---
**Author:** ![Plynck](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Plynck](https://boards.straightdope.com/u/Plynck)\ **Post date:** [November 20, 2005, 7:22pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/27 "2005-11-20T19:22:34Z")
> [@Burrido](#): > > Hmm, howabout writing “BLOODY MURDER!!” on walls and giving them the shits. REDRUM would do it for me… 😃 In my sophomore year, I kept getting woken up very late at night by a “Thunk, thunk, thunk” from the room across the hall (inhabited by a couple of stoners). Later I found that they had a dartboard on their door, and had painted the darts in fluorescent colors. Yeah, that was a scary thought - people stoned out of their minds throwing pointy objects at eye level … :rolleyes: ---
**Author:** ![Amaranta](https://avatars.discourse-cdn.com/v4/letter/a/6f9a4e/32.png) [@Amaranta](https://boards.straightdope.com/u/Amaranta)\ **Post date:** [November 20, 2005, 7:39pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/28 "2005-11-20T19:39:21Z")
> [@Larry Mudd](#): > > If you’re bored, you can draw patterns on your face with coffee. When they dry, they’re invisible under regular light but yellow under UV. First of all, I’d love to know how you found this out. Or maybe not; I’d prefer to think you were merrily drawing on your face with coffee one morning, as you do, and then walked in to a room with blacklight and observed. Second, next time someone crashes at my house, I’m so doing this. And replacing the bathroom light with a blacklight. ---
**Author:** ![LiveOnAPlane](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@LiveOnAPlane](https://boards.straightdope.com/u/LiveOnAPlane)\ **Post date:** [November 20, 2005, 10:07pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/29 "2005-11-20T22:07:31Z")
Great way to locate scorpions. ---
**Author:** ![Pixiesnix](https://avatars.discourse-cdn.com/v4/letter/p/898d66/32.png) [@Pixiesnix](https://boards.straightdope.com/u/Pixiesnix)\ **Post date:** [November 21, 2005, 12:23am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/30 "2005-11-21T00:23:23Z")
The arachnid or the band? ---
**Author:** ![LiveOnAPlane](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@LiveOnAPlane](https://boards.straightdope.com/u/LiveOnAPlane)\ **Post date:** [November 21, 2005, 12:55am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/31 "2005-11-21T00:55:43Z")
> [@KCSuze](#): > > The arachnid or the band? Jeepers, I guess it could be either, huh? 😉 ---
**Author:** ![MacTech](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MacTech](https://boards.straightdope.com/u/MacTech)\ **Post date:** [November 21, 2005, 1:13am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/32 "2005-11-21T01:13:18Z")
Looks like a normal Mini MagLite, right?, well…read on… [http://homepage.mac.com/mactechg4/.Pictures/UVMag4.gif](http://homepage.mac.com/mactechg4/.Pictures/UVMag4.gif) Tonight i went back to the Discovery store, to get a replacement for my Inova X0, as it had something in the collomator lens that _looked_ like a crack/scratch, didn’t affect the throw or light pattern, it was just unnerving having _something_ in an expensive flashlight… turns out _all_ the X0’s had that “line”, now it looks like either a hair, or it could simply be an image of the wires in the LED, the lens appears to be very well optically designed, it appears to be “normal”, and since it doesn’t seem to affect the light performance, i’ll live with it, and not let it bother me … anyway, to get to the point of my post… while i was there, i saw in the kids section, a little “kit” consisting of an “invisible ink” pen and a little UV LED “squeeze-light” the squeeze-light was simply a pair of 3V lithium button cell batteries with the LED leads straddling them and a clicker switch to push one of the LED leads onto the battery, it looked like i could simply pull the light apart and pop the LED in the head of one of my Mini Mag Lites… long story short, i grabbed one of my spare MML’s, unscrewed the head and shoved the LED into the holes, aside from the length of the LED leads, it was a perfect fit, i popped in the batteries…nothing…, so i simply reversed the polarity of the LED, and it illuminated! i then bored out the reflector to fit the LED through and reassembled the light, it was a little dim, but it lit, this was expected as i was only supplying it with 3V, not the 6V it was expecting, but the fact remains that it _was_ working, i’ll figure out a way to get 6V into the light somehow, maybe put in a pair of 3.6V batteries… …like the kind i have in my collection of old Macs out in the attic…hold on! YES!!! my _temporary_ rig of 1 3.6V lithium clock battery, 1 1.5v Alkaline AA and a piece of balled up aluminum foil has increased the light output from the LED dramatically, i know it’s a bad idea to mix battery types and voltages, that’s why it’s a temporary rig only, when i get into work tomorrow, i’ll try 2 3.6V lithiums and some foil spacers, and i may even risk it and go to 3 or even 4 3.6 V batteries, heck, if worse comes to worse and i burn out the LED, i’m only out a $7 UV LED… i’m going to hit the Discovery store tomorrow and pick up a few more of the UV squeezelight kits, just to have the LED’s as backups here’s some pics of my first succesful flashlight hack… pics of the light running on 3V (2 AA Alkalines) [http://homepage.mac.com/mactechg4/.Pictures/MiniMagUV2.gif](http://homepage.mac.com/mactechg4/.Pictures/MiniMagUV2.gif) [http://homepage.mac.com/mactechg4/.Pictures/MiniMagUV3.gif](http://homepage.mac.com/mactechg4/.Pictures/MiniMagUV3.gif) pics of the light running on 5.1V (3.6V lithium clock battery, AA Alkaline, foil spacer) [http://homepage.mac.com/mactechg4/.Pictures/UVMag.gif](http://homepage.mac.com/mactechg4/.Pictures/UVMag.gif) [http://homepage.mac.com/mactechg4/.Pictures/UVMag2.gif](http://homepage.mac.com/mactechg4/.Pictures/UVMag2.gif) [http://homepage.mac.com/mactechg4/.Pictures/UVMag3.gif](http://homepage.mac.com/mactechg4/.Pictures/UVMag3.gif) any hints on getting a good stable 6V (or more if the LED will handle it…) into a Mini Mag?, _how_ dangerous is it to run the light with it’s battery mix of voltages/types… ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [November 21, 2005, 8:52am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/33 "2005-11-21T08:52:42Z")
> [@moe](#): > > We often joked about how next year’s tenants of the room would react if they happened to bring in a blacklight and turn it on for the first time. > [@Burrido](#): > > Hmm, howabout writing “BLOODY MURDER!!” on walls and giving them the shits. If you don’t wash the stuff off the walls, and someone in the house smokes…eventually you CAN see the Tide, coming out as drippy brownish-yellowish goo that makes it look like the walls are bleeding nicotine just to tell you CLAPTON IS GOD. If your sister is 13 and she forgot that you painted on the walls with Tide last summer, and your sister is me, she will be mightily freaked out. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [November 21, 2005, 9:27am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/34 "2005-11-21T09:27:35Z")
A Gin-and-tonic has quite a respectable light-blue glow under UV. It’s the quinine in the tonic water, I think. ---
**Author:** ![neutron\_star](https://avatars.discourse-cdn.com/v4/letter/n/51bf81/32.png) [@neutron\_star](https://boards.straightdope.com/u/neutron_star)\ **Post date:** [November 21, 2005, 11:03am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/35 "2005-11-21T11:03:22Z")
> [@MacTech](#): > > when i get into work tomorrow, i’ll try 2 3.6V lithiums and some foil spacers, and i may even risk it and go to 3 or even 4 3.6 V batteries, heck, if worse comes to worse and i burn out the LED, i’m only out a $7 UV LED… I think you’re seriously overdriving it already. LEDs of any color or brightness that are rated over 4V max are pretty rare. If the plastic casing gets warm at all, it’s getting too much juice. Then again, you may have some kind of new LED that I’ve never seen before, especially considering that price. You can get a pack of 100 UV LEDs online for about $15, including shipping. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 21, 2005, 1:55pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/36 "2005-11-21T13:55:53Z")
Coca Cola under a black lite looks a wonderfully disgusting kind of green. One of my fond memories of college, where we had all our parties under UV lighting. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [November 21, 2005, 2:25pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/37 "2005-11-21T14:25:10Z")
Everyone here needs to be sure the enclosuers can handle the black light bulb your substituting. Black lights run hotter. The screw base 110V bulbs tell you to use only in a ceramic base. The flouresents and leds might not be hotter than the original, but you should be sure nooone the less. ---
**Author:** ![Tentacle\_Monster](https://avatars.discourse-cdn.com/v4/letter/t/ba9def/32.png) [@Tentacle\_Monster](https://boards.straightdope.com/u/Tentacle_Monster)\ **Post date:** [November 21, 2005, 2:34pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/38 "2005-11-21T14:34:29Z")
> [@Happy Lendervedder](#): > > But don’t ever take it to a hotel room. There are some things you just don’t need to see with your own two eyes. “Spittle… oatmeal… _semen!_ This must be the room where Bob Crane snuffed Wilford Brimley!” ---
**Author:** ![haardvark](https://avatars.discourse-cdn.com/v4/letter/h/b5ac83/32.png) [@haardvark](https://boards.straightdope.com/u/haardvark)\ **Post date:** [November 21, 2005, 5:56pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/39 "2005-11-21T17:56:19Z")
I spent a year in highschool crushing HARD on a gothgirl with big b’zooms. At one highschool dance she was wearing a black cableknit with a somewhat loose weave, and when the black light came on… Well, almost 20 years later and the memory is still razor sharp. _wistful sigh_ ---
**Author:** ![MacTech](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@MacTech](https://boards.straightdope.com/u/MacTech)\ **Post date:** [November 21, 2005, 6:06pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/40 "2005-11-21T18:06:47Z")
> [@neutron star](#): > > I think you’re seriously overdriving it already. LEDs of any color or brightness that are rated over 4V max are pretty rare. If the plastic casing gets warm at all, it’s getting too much juice. > > Then again, you may have some kind of new LED that I’ve never seen before, especially considering that price. You can get a pack of 100 UV LEDs online for about $15, including shipping. i honestly think the LED in the squeezelight was _underdriven_ by the stock batteries, right now i have the LED in the maglite housing being driven by 4 3.6V Mac “clock” batteries (1/2 AA size) and i’ve had it running for a half hour or more with _no_ heat buildup, the bulb stays completely cold, and it seems only marginally brighter than the previous config of 2 clock batteries and a spacer i don’t really use the light continuously for more than a couple minutes anyway, either using it to check for counterfit cash/credit cards/checks, or just showing it off as a “look at this, this is cool” toy cost of Maglite; free (it was one of my multiple spare Minimag bodies) cost of batteries; free, scavenged from my collection of old Macs cost of LED; $7 cost of building my own UV flashlight…Priceless! even _if_ the LED burns out, i’ll just pick up another one, and remove one of the clock batteries and put a spacer back in, try it on a slightly lower voltage… [Previous page](https://boards.straightdope.com/t/fun-with-black-lights/331758.md?page=1) [Next page](https://boards.straightdope.com/t/fun-with-black-lights/331758.md?page=3)