I use today’s art material to wash my clothes. Yes, you read that right! Or maybe I should say I paint with laundry detergent? Either way this is the easiest invisible ink you can experiment with. Pour, paint, let dry, and shine a black light on it. You’ll be shocked that it glows!
Please note: This post was originally created for PBS Parents Crafts for Kids and the instructions are no longer available on their website. I’m including directions here now .
Did you know that many laundry detergents glow in the dark? Most of them contain phosphors, a powder that glows or Fluoresces under ultraviolet light AKA black light. Use them to paint hidden pictures that are only revealed in the dark!
Why are there phosphors in detergent? So why does something you use to clean your clothes contain fluorescent powder: The phosphors are used to make whites appear whiter when seen in bright light by adding in a touch of blue.
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Hidden Pictures Materials
- Laundry detergent Test a small amount of detergent under a black light first to make sure it contains phosphors. We used the Trader Joes liquid laundry detergent.
- Black paper
- Paint Brushes
- Black Light You must use a fluorescent black light. Incandescent black light bulbs are not powerful enough. You can also try a blacklight flashlight like this.
Hidden Pictures Instructions
Time needed: 10 minutes.
Paint with “invisible ink” and then make your pictures glow under black light!
- Prep your materials
Pour laundry detergent into a container. Place paper on a table with a tray underneath.
- Paint a picture
Use the detergent like paint on black paper.
- See it glow!
Go into a very dark room with a black light. Hold up your pictures near the light. They will glow!
- Let Dry
The images will fade as the detergent dries.
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Hi Ana,
would a CFL black light bulb work? THANKS!
like this one: http://www.amazon.com/Feit-Electric-BPESL15T-BLB-Incandescent/dp/B000I1AE20/ref=sr_1_10?s=hi&ie=UTF8&qid=1446049353&sr=1-10&keywords=fluorescent+black+light
Hi Joely,
Good question! I know the incandescent version will NOT work. I would imagine this bulb would work though I do like the strip fixture because it’s so powerful. It’s the type you see on lots of outdoor Halloween displays right now. If this bulb works will you let me know?
Yes!
This looks fun. Don’t have a black light though. 🙁
I think they are worth investing in. We’ve been able to do loads of glow-in-the dark projects because of the one we bought a couple years back 🙂
Hey!
Do you think this would work on white paper?
Have you ever tried it on a black tshirt. I wonder if that would work too.
I have not but it would be interesting to try!
Hey… Its pretty awesome. This project is really interesting for my kid.