At-Home Science Experiments: Flower Rainbow

Chromatography is a lab technique for separating mixtures. Our kitchen-friendly version uses Popsicle sticks and coffee filters.

By Margit Ragland



What You'll Need:

  • Cereal bowl
  • 2 Popsicle sticks (you could also use straws or twigs from the backyard) 
  • White coffee filter 
  • Scissors 
  • Black washable marker (Crayola and RoseArt produce best results) 
  • Piece of paper towel (about 3" x 3")

What To Do:

  1. Fill the bowl about halfway with water. 
  2. Balance the Popsicle sticks horizontally across the bowl with a small space (about 1.5") between them. 
  3. Snip a small hole in the center of the coffee filter. 
  4. Using the marker, draw six small dots, evenly spaced, around the hole. Each dot should be about 3/4" from the hole. Add more dots if you’d like. 
  5. Tightly roll or twist your paper towel so that it’s like a rope and thread it through the hole in the coffee filter. 
  6. Balance the coffee filter on the Popsicle sticks so that the open end of the filter faces up toward the ceiling and the end of the paper towel rope coming out of the bottom of the filter just touches the water. 
  7. Watch for 1 to 3 minutes as colors begin to swirl out of the black dots on the coffee filter! 
  8. To make a flower, trim the excess paper from the filter. Pinch in the middle, then tape to a straw, pipe cleaner, or twig. 

What’s Happening:

The paper towel rope absorbs water from the bowl and carries it up to the coffee filter. The filter absorbs the water, and the water molecules spread through the paper. When the water hits the black dots, it grabs the different-colored molecules that make up the black ink (yep, black isn’t made from just one hue!) and carries them as it keeps moving through the filter. That’s why you see a rainbow form when the ink molecules separate. Like the ink, many things in our lives (beverages we drink, lotion we put on our skin) are mixtures of various substances. When we separate the different components, it’s called chromatography.

Our expert: Will Tyler, 4th grade science teacher at Bells Ferry Elementary School in Marietta, GA

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