SaH: Rainbow Milk

The fat content of milk is the reason this experiment works so well! Discover how soap interacts with fat molecules. In addition, you will be able to see what happens when you mix red and blue, blue and yellow, and yellow and red. Art and science together make this experiment picture worthy! Share your results in the comments below.



  • 1 small bowl
  • Food color: red, blue, yellow
  • Dish soap
  • Toothpicks
  • Whole milk


What To Do

  1. Fill a bowl with a small amount of whole milk.
  2. Place a drop of each primary color in the milk – try to not move the bowl.
  3. Dip a toothpick in dish soap and gently drop it into the bowl and watch.

What happens to the colors?

What is happening?

Dish soap is great at cleaning fat off of dishes, and milk has fat in it. The soap repels – or pushes – fat away from it. As this happens the colors move with the milk and are mixed together! When the primary colors red, blue and yellow mix together, they make the secondary colors purple, green orange!

What other liquids could you try this in?

What do you think would be different?

Share this post!

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