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  • Sara Thompson

At-Home Rainbow Experiment

By Sara Thompson

Special to the Enterprise

Cups with red, blue, and yellow liquid in them
Experiment in progress; Photo from

Spring is here and vibrant colors are appearing in the world around us. Light shows up beautiful rainbows from spring rain showers or through glass prisms. You can make these colors in your own home using some simple supplies that many of you already have.

The supplies you will need for this experiment are: 5 short, clear cups (small plastic or glass mason jars work well), red, blue, and yellow food coloring, water, spoon, scissors, paper towels, and optionally a tray or large baking dish to contain any spills.

Line up your clear cups in a row. Fill cups 1, 3, 5 with water about ½-¾ full. Add red food coloring to the first cup, blue food coloring to the 3rd cup, and yellow food coloring in the 5th cup, about 5-6 drops each should work. Use the spoon to mix the colors in with the water. Next, take a paper towel fold it in half lengthwise. The experiment recommends the perforated half sheets, but if you have full sheets, use your scissors to cut them in half lengthwise. Continue folding until your paper towel is around 1-2 inches wide. Place one end in the red cup and other end in the empty cup next to it. Use the scissors to trip any excess paper towel so it is not sticking up too far out of the cup. Place another folded paper towel in the yellow cup and the other end in the empty cup beside it. Next, place two more folded paper towels in the blue cup in the middle, with each of the ends in the empty cups on either side of it. You should now have 5 cups lined up with paper towels connecting them.

The next step should only take a couple of minutes so you can sit and watch the process or leave and come back after a few minutes to see the results. The paper towel absorbs the colored water all along its length, this is called the capillary effect. The water will travel along the whole paper towel and some will begin to fill the empty glasses in between the cups originally filled with water. Because each empty cup will have two paper towels leading into it with a primary color, the colors will mix making the secondary colors of purple between red and blue, and green between blue and yellow.

You can also do this experiment with 7 cups, producing even more colors! Set up the experiment the same way as above, but in the 7th cup water with red food coloring. The empty cup between the yellow and red color will produce orange.

We hope you enjoyed this fun and colorful home experiment with your family. For more hands-on experiments for the whole family visit our current exhibit “Healthy Planet, Healthy You”. Explorit is open to the public on Fridays from 1-4pm, Saturdays and Sundays from 10am-2pm. Admission is $5 per person. Explorit Members, ASTC, and those age 2 and under free. Masks will continue to be required for entry.


Exploit's coming events:

• Spaces are still available for our Summer Science Camps for those entering grades 3-6. All camps run from 9am-12pm Monday-Friday and will have both indoor and outdoor components. Price is $175 Members/$200 Non-Members. Register for summer camp at Camp spaces are limited, so sign up now!

• A Membership to Explorit not only supports us but grants the recipient free visits to Explorit’s regular public hours, discounts on events, summer camps and workshops, and gives you ASTC benefits to visit other museums throughout the world. To purchase or for more information visit or call Explorit at 530-756-0191.

• Like many small businesses the closures have had a significant impact on our income and sustainability. Now is a great time to donate and help Explorit continue to educate and inspire the scientists of tomorrow:


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