Turn Your Phone Into a Black Light Hack





Introduction: Turn Your Phone Into a Black Light Hack

Turn Your Phone Into A Black Light Hack. Its super easy to do!

All it takes is a smartphone with a light, three pieces of small tape and two sharpies. One blue, one purple.

Take the first piece of tape, put it over the camera flash on the back of your phone. Color that tape blue. Repeat this step again. After you've put both layers of tape onto the flash or light of your camera, put the third and final layer on top of that one. This is where you pull out your purple Sharpie and paint that sucker in.

Things You Need:
-Smart Phone

-Scotch Tape

-Blue Sharpie

-Purple Sharpie

Step 1:

Step 2:

Step 3:

Step 4:

Step 5: Turn Flashlight On



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    Hi, I have also determined that some phones are better than others.

    A good test is to see if the LED makes things fluoresce, notably blue/green EL wire or other nearby white LEDs. If so them this will work very well.

    If not then some phones let you increase flash power to 100% and there's actually a hack to boost it at the cost of LED lifetime, or even just replace the diode with a dedicated blacklight microLED and white phosphor external add-on array (cough SMD soldering is REALLY difficult and needs steady hands and 63/37 solder /cough) I've since found them for sale for about 60p a unit.

    Thank You for posting this hack. I needed a cheap and easy solution to see which of my on hand materials would react under uv. This worked a treat, Thanks again.

    I made this, I might've done it wrong because it didn't work. At all. I tried with just the torch on and I tried taking pictures with flash, nothing worked, it just looks like a cool filter on the flash rather than a "black light"/UV light. Damn.

    Your not making a blacklight. A blacklight is a UV-A bulb. No cell can produce uv light. Your just making the led camera light cobalt. Blue light will make things fluoresce a little but, no where near what uv-a, uv-b, or uv-c bulb will. It's a waste of time. Just go buy a real blacklight blue UV-A light about 24 inches long. There like 15 bucks.

    You are basically making a "Wood's Glass" filter just like the glass on an incandescent Black Light, light bulb. It might work but not much power will be emitted at the ultraviolet wavelength from most white LEDs used for cell phone flashes. You need energy in the 100nm to 400nm wavelengths and most will be in the 300nm to 400nm.

    I'm going to give it a try, I'm betting finding the exact right the markers will make a pretty huge difference.

    Saw this on Facebook and doubted its validity, but I researched it anyways. First, in order for something to fluoresce, it needs to respond to UV light at the following wavelengths: Long-wave315-400nmLWUVA, Mid-wave
    280-315nm or Short-wave
    100-280nm. The graph below shows the emissions of a White LED used in a smartphone. 400nm and shorter (to the left), there are NO emissions. Hence no UV. Second, all that plastic tape would absorb UV light if there were any. Lastly, the odds of creating a UV bandpass filter with sharpies and scotch tape, pretty much don't exist. Not being mean, just stating the facts. The video "proof" was probably shot with a true UV lamp as the light source.


    This is not a "black light". What you know as "black light" is ultraviolet light, which is unproducable with a standard camera flash. These operate within the visible light spectrum, which is far too low to emit UV. In addition to this, you are filtering out the blue band of the spectrum, not the violet (which would at the very least be closer). Check your information before submitting.

    In addition to this, the source of your pictures is dubious. They appear to be from an external source (and a poorly-informed one, at that).


    "Blacklight" is UV light, something not emitted at all by a phone's flash.

    All you are doing here is filtering out the red of the phone's white light, leaving the blue end of the spectrum. OK as a prop for cosplay or Hallowe'en, but it is not a working blacklight.

    I'm also very tempted to call "foul" on the still images, which had been around the web for months before you published the video.

    There are technically two common types of black lights. This one creates a light very similar to the "black lights" you buy at party stores.