# Fun with Black Lights....
**URL:** https://boards.straightdope.com/t/fun-with-black-lights/331758
**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:** 1
### Author:  [@MacTech](https://boards.straightdope.com/u/MacTech)
#### Post date: [November 19, 2005, 2:43am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/1 "2005-11-19T02:43:30Z")
on a whim, i picked up a cheap $10 battery powered flourescent black light from Spencer Gifts, primarily to test something i read on the internet somewhere (so it must be true, right? š )
apparently, the security thread in US paper currency will flouresce under ultraviolet lightā¦
it does, the $20 and $10 bill security thread glows yellow,the thread in the $5 glows blue (i donāt have a $50 or $100 available, iāll test the ones in the cash drawer at work on Monday)
i also discovered that many credit cards also have security features that glow under black light, my Citibank MasterCard has the letters M and C show up in ghostly blue, and even cooler, my Visa debit card has a faint blue glowing Visa Dove in the body of the cardā¦
so i walked around the house, seeing what else glows, as the flourescent light hit my old Dual USB iBook 500, the keyboard glowed a bright blue, much brighter than the surrounding plastic, it was glowing bright enough to use as a ābacklitā keyboard, now all i need to do is rig up a simple ultraviolet LED lighting system for the 'Book, and itāll be the only iBook with an illuminated keyboardā¦
as i approached the aquariums, i shone the light in there, and my pet common Florida Crawfish (Procambrias Alleni) glowed a faint _green_ (and quickly hid from the UV light), i guess it kindaā makes sense, as scorpions flouresce and they have a similar chitinous exoskeletonā¦
one of the unknown stem plants in my 20 Long also flouresces, a bright green, just the stem only thoughā¦
i wonder what else will glow under black lightā¦
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### Author:  [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)
#### Post date: [November 19, 2005, 2:55am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/2 "2005-11-19T02:55:12Z")
If youāre wearing dark clothes, lint will show up under a black light.
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### Author:  [@Larry\_Mudd](https://boards.straightdope.com/u/Larry_Mudd)
#### Post date: [November 19, 2005, 3:00am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/3 "2005-11-19T03:00:00Z")
If youāre bored, you can draw patterns on your face with coffee. When they dry, theyāre invisible under regular light but yellow under UV.
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### Author:  [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)
#### Post date: [November 19, 2005, 3:44am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/4 "2005-11-19T03:44:09Z")
Anything white.
Any glow in the dark objects.
Cheap dentures to the horror of Disco Steu.
Some minerals.
Some organic compounds.
Fish aquariums have special bulbs you can buy that include light in the UV range. The fish look much better under that lighting.
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### Author:  [@Rhubarb](https://boards.straightdope.com/u/Rhubarb)
#### Post date: [November 19, 2005, 4:06am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/5 "2005-11-19T04:06:26Z")
Sebum. It fluoresces yellow/orange. Donāt ask me how I know this.
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### Author:  [@MacTech](https://boards.straightdope.com/u/MacTech)
#### Post date: [November 19, 2005, 4:24am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/6 "2005-11-19T04:24:46Z")
my checks also have a series of flourescent fibers woven into the paper, my teeth have a faint yellowish-green glow (probably from the coffee stains)
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### Author:  [@SnakesCatLady](https://boards.straightdope.com/u/SnakesCatLady)
#### Post date: [November 19, 2005, 4:34am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/7 "2005-11-19T04:34:33Z")
Ringworm glows under a blacklight.
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### Author:  [@A.R.Cane](https://boards.straightdope.com/u/A.R.Cane)
#### Post date: [November 19, 2005, 4:34am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/8 "2005-11-19T04:34:49Z")
Many vinyl records will turn bright colors, red, green, etc., although some do not, I
guess it depends on the polymer materials?
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### Author:  [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)
#### Post date: [November 19, 2005, 5:15am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/9 "2005-11-19T05:15:02Z")
Any remains from pet accidents on the carpet will glow.
Pet shops actually sell small blacklights under the brand āStink Finder.ā
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### Author:  [@Ms\_Macphisto](https://boards.straightdope.com/u/Ms_Macphisto)
#### Post date: [November 19, 2005, 9:15am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/10 "2005-11-19T09:15:27Z")
I need to pick up one of those. Iāve been told that my contact lenses glow green under black light, but Iāve never managed to be anywhere that has both black light and a mirror in which I can see my glowing eyes. I have startled a few people though. š
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### Author:  [@Happy\_Lendervedder](https://boards.straightdope.com/u/Happy_Lendervedder)
#### Post date: [November 19, 2005, 9:43am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/11 "2005-11-19T09:43:44Z")
> [@MacTech](#):
>
> my teeth have a faint yellowish-green glow (probably from the coffee stains)
But how do they look under a black light?
š
> [@](#):
>
> Sebum.
Another two-syllable glandular secretion starting with the letters āseā also glows under blacklight.
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### Author:  [@Seven](https://boards.straightdope.com/u/Seven)
#### Post date: [November 19, 2005, 10:23am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/12 "2005-11-19T10:23:19Z")
Take the black light into the laundry room š
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### Author:  [@Happy\_Lendervedder](https://boards.straightdope.com/u/Happy_Lendervedder)
#### Post date: [November 19, 2005, 10:37am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/13 "2005-11-19T10:37:00Z")
> [@Seven](#):
>
> Take the black light into the laundry room š
But donāt ever take it to a hotel room. There are some things you just donāt need to see with your own two eyes.
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### Author:  [@irishgirl](https://boards.straightdope.com/u/irishgirl)
#### Post date: [November 19, 2005, 12:18pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/14 "2005-11-19T12:18:27Z")
Lots of toilets in pubs, bars and train/bus stations have installed them, supposedly to prevent junkies from locating veins and to make it harder for them to shoot up in said toilets.
Since I have seen a longtime heroin abuser locate a vein in her neck without any trouble (I couldnāt find a vein to take blood from, so she did it for me!) I am :dubious: about this concept. You donāt see veins, you feel them.
You can test this out if you wantā¦see if you can locate any of the veins in your arm!
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### Author:  [@zagloba](https://boards.straightdope.com/u/zagloba)
#### Post date: [November 19, 2005, 12:19pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/15 "2005-11-19T12:19:50Z")
> [@Happy Lendervedder](#):
>
> Another two-syllable glandular secretion starting with the letters āseā also glows under blacklight.
But what about smegma?
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### Author:  [@matt](https://boards.straightdope.com/u/matt)
#### Post date: [November 19, 2005, 6:54pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/16 "2005-11-19T18:54:23Z")
> [@Ms Macphisto](#):
>
> I need to pick up one of those. Iāve been told that my contact lenses glow green under black light, but Iāve never managed to be anywhere that has both black light and a mirror in which I can see my glowing eyes. I have startled a few people though. š
Maybe I was a bit hasty when I staked a girl through the heart in a nightclub and decapitated her corpse. Still, better safe than sorry!
Itās when you donāt show up in the mirror that you really have to worryā¦
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### Author:  [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)
#### Post date: [November 19, 2005, 9:35pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/17 "2005-11-19T21:35:44Z")
These are the greatest. I went to a few in college. Loads of fun, although you do need to work up a second costume, built around white washables. (Thereās something fluorescent ā I believe itās the bluing ā in detergents.)
Not recommended if you have had many doggie or kitty accidents.
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### Author:  [@MacTech](https://boards.straightdope.com/u/MacTech)
#### Post date: [November 19, 2005, 11:12pm UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/18 "2005-11-19T23:12:38Z")
> [@Beware of Doug](#):
>
> These are the greatest. I went to a few in college. Loads of fun, although you do need to work up a second costume, built around white washables. (Thereās something fluorescent ā I believe itās the bluing ā in detergents.)
>
> Not recommended if you have had many doggie or kitty accidents.
and unless you have a very strong stomach, _DO NOT_ look at a toilet under UV illumination \ mustā¦bleachā¦brain!
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### Author:  [@Burrido](https://boards.straightdope.com/u/Burrido)
#### Post date: [November 20, 2005, 2:26am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/19 "2005-11-20T02:26:36Z")
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.
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### Author:  [@Lillith\_Fair](https://boards.straightdope.com/u/Lillith_Fair)
#### Post date: [November 20, 2005, 3:04am UTC](https://boards.straightdope.com/t/fun-with-black-lights/331758/20 "2005-11-20T03:04:19Z")
I have an anniversary ring that has five identical diamonds (not big ones!!). But under a black light each one is a different color, so the are obviously not identical. They are shades of pink to purple. Itās pretty. And weird.
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