Simple to try, yet really cool to watch! A classroom favorite, the capillary color activity is also fun to experiment with at home. Don’t limit yourself to just one color mixing combination, create several and compare your results. Some call this “walking water,” but cool color collisions also make this visually fun!
What you need:
- 3 empty glasses (more if you want to try more than one combination)
- Food coloring
- Paper towels
What you do:
- Select the colors you want to mix together. Red/Blue Yellow/Red Blue/Yellow .
- Fill only two of the glasses with 2/3 water.
- Add one color each into the glasses.
- Cut a paper towel in half and then fold it into quarters lengthwise.
- Stick one end of the paper towel into the colored water and one into the empty jar in the middle.
- Make sure that the paper towels in both the empty jar and colored water jars are hanging down almost to the bottom.
Wait, and watch! What happens to the jar in the middle?
Why does it work?
The water moves or climbs up the paper towels into the empty jar using capillary action. “Capillary action” is the when a liquid to flows and fills in narrow spaces without the assistance of, and in opposition to, external forces like gravity. Water molecules want to “stick together” and fill space, so they stack on one another to fill the gaps in the paper towel. The middle jar fills with water until the water levels of all the jars are the same and the colors mix.