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Rainbow Walking Water Experiment

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We had fun this week doing a few different kinds of rainbow science.  Have you ever tried the rainbow walking water experiment?  It’s an awesome one.

rainbow absorption science- walking water

This is an update on a post I did more than 10 years ago.  I love freshening up my older posts with better pictures. But also, I love re-doing favorite activities with my younger kids.  I get to experience the joy and wonder on their faces all over again!

In this experiment we explored how paper towels absorb water and seeing a rainbow of colors!  The kids loved doing these simple experiments. They learned all about colors and absorption.

We did two different experiments at the same time- both are very simple and require only things you’ll already have in your home.

Rainbow Walking Water Experiment

The first experiment we did is called rainbow walking water.

rainbow walking water experiment with kids

You just need 6 cups or jars, paper towels and food coloring or liquid water colors.

Watch it in action:


Fill three of the cups with water, and leave the other three empty. The three cups with water, you will add the food coloring too. Use the three primary colors- red, yellow and blue.

making rainbow water experiment

Then you will need 3 empty plastic cups.  It is nice to have clear ones so you can watch the process. Put the cups into a circle.

supplies rainbow walking water experiment
Take the paper towels and fold them up into strips. Folding into thirds works well.  I used small bathroom size cups so I cut the paper towels a bit shorter to fit better.
rainbow walking water with kids
Then put one end in the colored water and one end into the empty cup.  You mill be mixing colors, so use primary colors that blend.
Yellow + Blue = Green
Red + Blue = Purple
Red + Yellow = Orange
yellow and blue mixing

The water will begin soaking up the paper towel and into the empty cups mixing the two colors together and making a secondary color. I loved how the yellow and blue came together in this cup!  So cool!

It takes a long time, so tell your kids that this is something you will be watching all day long.

Tip: When you use smaller cups, it goes more quickly.

My kids thought this was so cool.  It started conversations about absorbing and also primary & secondary colors which is always great!

The Science Behind the Walking Water Experiment:

Why does this work? This works because of a capillary action. What’s that?  Think of plants and how the water goes from the ground up through the roots and stems all of the way to the leaves and flowers. That is capillary action.

Capillary action is the ability of a liquid to seemingly defy gravity and move upward through small spaces. This is due to the forces of the water and the object it is traveling through. In this case the water molecules are adhering to the paper towels.

 Rainbow Science: Absorption

Here is the next simple rainbow science idea to show absorption:
 Rainbow Science- Absorption
Get a paper towel and make some big circles of various colors on the bottom.  You want to leave a little space at the bottom.

In a plastic container- I used a small clear plastic storage bin, but you could use a bowl, or whatever you have on hand- put a small amount of water, enough to just reach the bottom of the paper towel.  You don’t want the water level to reach the colors on your paper towel or it will make a swirly mess of colors.  Believe me, we did that first.  Place the paper towel into the water- just hang it over the edge.

The water soaks up the paper towel bringing all of the colors with it making a wonderful rainbow.  My daughter who loves painting and colors was just so excited about this.  She thought it was beautiful!!

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