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.
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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