My kids had some friends over for a play date and we decided to take a break from running around for a few minutes to do this fun, simple science experiment showing color mixing. The kids loved watching the empty cups fill with colors that weren’t there before.

Science Question:

How does a paper towel soak up a spill?

Paper towels, like the trees they come from, soak up the water through capillary action”. The plant fibers pull the water up the towel.

Prep Time: 5 Minutes, Plus an hour or so to sit.
Experiment Duration: 15 Minutes

Supplies Needed:

  • Scissors
  • Paper Towels
  • 6 Clear Glasses
  • Water
  • Red, Blue, and Yellow Food Coloring

The Experiment

Cut the paper towels into six strips that are approximately 4 inches wide. Fold them in half to make 2-inch strips.

Fill three of the glasses almost to the top with water. Add food coloring to each cup (one red, one blue, and one yellow). You will need 10-15 drops of food coloring per cup. Place the glasses in a circle, alternating with the three empty glasses.

Drape the paper towel strips between the glasses so half of each towel is in a colored glass and the other half is in an empty glass.

The Outcome

The water in the filled glasses will climb up the paper towels, through the plant fibers, and drip into the empty glasses. The colors will begin to combine. Red and blue will mix to become purple, yellow and red will make orange, and yellow and blue will make green.

Let the towels set in the jars for a few ours or even overnight. The towels and glasses will look like a color wheel!

Why it Worked

The capillaries (tiny, long tubes) in the plant fibers soak up the water, bringing them up the paper towel through cohesion (where the water molecules stick together).


See how high you can get the water to climb! Try this experiment with a dish of water and a longer length of paper towels, suspended a couple of feet in the air, such as off the edge of a table, and dropped into the dish.

Did you Know?

Paper towels were invented after a batch of bad toilet paper couldn’t be sold. Arthur Scott in 1907 repurposed the failed paper into towel-size sheets and voila!- disposable towels.

Experiment from:
Miller, Rachel, Holly Homer, and Jamie Harrington. “Rainbow Water.” The 101 Coolest Simple Science Experiments: Awesome Things to Do with Your Parents, Babysitters and Other Adults. Salem, Massachusetts.: Page Street, 2016. 136-37. Print.