Introduction: Create Homemade Fluorescent Black Light/UV Displays

About: Gian is a computational biologist,maker, author, humorist. He holds degrees in Molecular/Cellular Biology, Biochemistry, Computer Science. He has a collection of 8-bit microcontrollers and a room full of compu…

Black lights (formally, Ultraviolet or UV lights) are just fun.  Not only are they great for when you are in a trance, but they can be used to identify those questionably unidentifiable stains on your bf's or gf's clothes.  But the coolest thing is how certain colors or chromophores react with UV lights.  Whites and fluorophore compounds (chemical side chains responsible for fluorescence) are especially colorful under a good UV lamp or array of UV LEDs.

In this instructable, I'll show you how to create your own fluorescent compounds out of something you probably already have in your home.

Step 1: Gather Your Items

What's the first thing that comes to mind when thinking about fluorescent ... well, besides fluorescent lighting?  Fluorescent markers, that's what!  Otherwise going by "Hi Liters" or some such thing, these humble little buggers are just screaming to be used for something besides highlighting organic chemistry text books.  And we're going to listen to their plea.

Grab some highlighters from your desk, bureau, backpack, friend's locker, mom's know, wherever.  They're lying all about if you really look for them, those unassuming little pearls hiding right in front of our piggish noses.  You can use the big fat ones or the slimmer bic-type highlighters, depending on how much fluorescent solution you want to make.  The slim versions are fine to make about 150mL to 200mL, depending on how much highlighter fluid is in the highlighter pen. The fat highlighters can make upwards of 500mL of fluorescent solution.

Now, go get 'em!

Step 2: You've Got to Get to the Marrow

For this step, break open your hilighters.  I've found some pop off easily from the rear (I should retype that sentence) while others offer a bit of a struggle.  For the overdoer in our crowds, grab your dremel and cut that sucker open.  That's what I do.  Any occasion to cut anything open I use the faithful dremel.  I like it so much I have three, just so I can cut three things open at once.  Seriously.

Anyway, check out some of the pictures. 

Once you have the pen broken open, cut open, or otherwise dissected, you should find a fibrous center shaft that contains the ink.  Be careful and don't squeeze it when pulling it out of the pen's shaft.  Be prepared to transfer it immediately into a reservoir of water.  Being a biochemist, I use 150mL autoclave bottles but you can get by with anything as long as it's watertight.  For the water, I use distilled water at ambient room temperature (~ 25 Celsius) but again, for the less anal retentive, you can get on well with just tap water.  Regarding temperature, I've tried warm water to increase the rate of transfer of ink into water, but something about my brain prefers ambient to cool water.  Don't use ice water, m'kay?

Step 3: Soak the Ink Shafts

You've got the fibrous ink shafts out, so drop it in your waiting 150mL or so container of H2O.  It's more prudent to use less water than more, as you can always dilute it later if it's too concentrated.  You know it's too concentrated because it won't fluoresce.  If this happens to you, just add more water to dilute the solution until a UV LED casts a solid shaft of light through the fluorescent solution and causes the rest of the fluid to fluoresce nicely.  You'll know it when you see it.

Soak those ink shafts for a while, at least until the fibrous shafts are blanched clean/white.  Personally, I soak for about a day or two, but you can probably get most of the ink out in several hours.  Try turning the bottle every now and then or agitating the solution -- not by calling it names or hiding its homework, but by shaking it gently back and forth.

When the shafts are blanched pull them out and check the concentration with a UV LED and proceed to dilute if necessary.  You probably won't need to if you use a thin highlighter.  I've found that even thick yellow highlighters make a very bold fluorescence in 150mL while the same concentration in another color doesn't fluoresce at all.  Try yellow, green, pink, blue, or any other color that you find and like. 

Tighten off your bottles and save them back as your fluorescent stock to use in fun and interesting LED/blacklight lamp projects.

Step 4: Some Ideas

You can fill bottles (like empty clear bottles, especially neat if antique or laboratory looking) with your fluorescent solution and just put them somewhere, like a stand or curio cabinet or the top of your cabinets next to your beer bottle collection.

Another idea is to take clear plastic tubing and hold one end with your thumb while you pipette or use an eye dropper to aloquot solution into the tube.  It's a tricky endeavour as putting in the solution displaces air, which wants to go out your thumb side.  Play around with it.  When you're satisfied with the filling, cap off both ends with hot glue.  Consider getting UV SMD LEDs and running magnet wire behind the tubing with your LEDs.  It looks fantastic.

A final idea is to get some sort of scintillation vial (that's chemistry talk for a small vial with a screw-on, watertight cap) and:
  1. drill two holes in the cap
  2. take a 5mm UV led and thread the leads through the holes
  3. seal off the metal with silicon glue of any variety (i use "tough as nails")
  4. seal off the cap inside
  5. fill up the vial with your favorite fluorescent solution
  6. screw on the lid, adding more solution until there's no bubble
  7. now connect 3-5V via a 120 ohm resistor to the LED
Voila!  You have an encapsulated fluorescent container with black light integrated that you can add to many projects (blink it from a 555 timer, pulse dim it with PWM from an MCU, etc).  I may post a project using them in a separate instructable later.

Step 5: Conclusion

I hope you've enjoyed this instructable.  It's easy and inexpensive fun for you and the kids (just make sure they don't drink it).  I hope I was able to share something new and fun with you.  As always, I am open to comments and suggestions on this or any of my instructables.


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