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Make a Milk Rainbow

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20 buddy reviews
by Teisha Rowland, PhD
Active Time
10-20 minutes
Total Project Time
10-20 minutes
Key Concepts
physics, chemistry, liquids, molecules, surface tension
A black plate with a rainbow on it made of milk and food coloring.


Have you ever seen a rainbow after a rainfall, or drawn a rainbow for fun? They can be fun to make using colorful markers or other craft supplies. But did you know you can actually make a simple rainbow using milk, liquid detergent (i.e., soap), and food coloring? How the rainbow is created by this mixture might surprise you! In this science activity, you will make your own milk rainbow and explore how detergent and surface tension are involved in its creation.


Teisha Rowland, PhD, Science Buddies
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,150 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.


  • Milk; 1%, 2% or whole. Avoid using non-fat milk.
  • Red, yellow, green, and blue food coloring if you want to make a rainbow. Or substitute any colors you want.
  • Liquid dish soap or liquid laundry detergent
  • A plate or some other type of shallow dish, such as an aluminum pie tin. Make sure the bottom is flat and not wrinkled.
  • Cotton swabs
  • Paper towels are useful for cleaning up afterwards
    Materials for making a rainbow from milk, food coloring, and soap.
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Active Time
10-20 minutes
Total Project Time
10-20 minutes
Key Concepts
physics, chemistry, liquids, molecules, surface tension