By Colie Haahr, CMNH Educator

This project is fun and easy, and only requires a little bit of prep ahead of time. Kids will enjoy magically making a rainbow appear by adding water to a paper towel. This activity is fun on its own, or it can be set up as an experiment that they can try a few times and record the results.

Materials Needed:

Paper towels
Washable markers
Black permanent marker
Cup for water
Tray or plates 
Pipette, eye dropper, or small spray bottle
Optional: Different brands of markers, highlighter, permanent markers, pencil, pen 

Directions:

• Prep ahead: This project requires some prep ahead if you want to create a truly “secret” rainbow! You can create more sheets for kids to try as you go if they enjoy the activity! -Use a water based marker to create a rainbow on a paper towel. Remember ROYGBIV! 

-Thin lines work well for this- do not make them too thick because you need to cover them with permanent marker

-Use a black permanent marker to carefully draw over each line, hiding the colorful lines under the dark lines. 

-Optional: create shapes that are different colors, and use the same process to cover them with permanent markers. 

-Optional: Set up the color mixing part of the activity the same way coloring two circles next to one another in primary colors (red and yellow, red and blue, and yellow and blue)

• Place one of the prepared paper towels onto a plate or tray that is okay to use for an art project (it may get marker ink on it!), with a cup of water and pipette or spray bottle

• Make a prediction- ask: what do you think will happen when we add water?
• Ask kids to slowly add some water to the picture
• The rainbow will “magically” appear when the water based marker dye spreads, and the permanent ink stays in place
• Try the same method with color mixing, or the colors hidden behind shapes
• Let the artwork dry completely, and some of the dye will stay on the paper towel once it dries. Too much water can cause the color to wash out completely
• Alternatives: This also works with a tray of water, and kids can carefully place the paper towel in the water and watch what happens. 

-Make an experiment! To make this a true experiment, try using different types of writing utensils, like markers, pens, pencils, highlighters, etc., and testing each one to see if water changes anything. Compare different brands of markers to see which ones work the best. Make predictions and write down the results! 

Science Information: 

For this activity there were two types of markers used, and they were made of different types of dyes or inks. One was water soluble, and one was not. If the experiment went as planned, the water based markers should have spread color out on the paper towel. These markers have dye that is water soluble, which means that it is able to dissolve in water. 

The permanent marker has a different kind of ink or dye, and it is not water soluble, which means that water will not wash it away. The permanent marker is alcohol based, so it will dissolve in alcohol. If rubbing alcohol were added to the paper towel, it may have changed the permanent marker, but because only water was added, the permanent marker stayed the same.  

The paper towel also played an important part in making this activity work. This activity did not work well on other types of paper, like card stock and copy paper. Paper towels are absorbent, and designed to absorb or suck up liquids. If the paper were waxed paper or something similar, the water would bead up into droplets because water molecules like to stick together. Water molecules still like to stick together on paper towels, but there are tiny air pockets in paper towels, and a soft cellulose material that allows the water molecules to move around the paper towel together. 

References:

https://indianapublicmedia.org/amomentofscience/how-do-paper-towels-absorb-water.php

https://www.thebestideasforkids.com/surprise-rainbow-activities/